This Old (green) House

• As Posted On www.thisoldhouse.com
  The architecture may be old at This Old House's new project in Austin, Texas, but the thinking is thoroughly modern. For the first time, the show is going totally "green"—using as many environmentally friendly building products and methods as possible—and creating a functional home for a contemporary blended family.
  
  The subject of the renovation is a 1926 Craftsman bungalow that owners Michael Klug, 38, co-founder of a hologram company, and Michele Grieshaber, 41, a marketing executive, are turning from a two-bedroom, one-bathroom house into one with four bedrooms and two baths. Michele has owned the house for the past decade, but the couple married this past April and need more room to accommodate their new family, which includes Michael's two sons, Sam, 13, and David, 11. Add in the possibility of another child in the future, and it becomes clear that a house built for the lifestyle of a 1920s family won't cut it for this 21st-century clan.
  
  That said, there are many things about the house's original design that the couple plans to preserve and honor. Built before the days of hulking McMansions with 24/7 air-conditioning, the compact house was built to use natural air flow, high rooflines, and deep overhanging eaves to keep the heat at bay. It was efficient and green, and Michael and Michele have no intention of turning it into a oversized, over-cooled monstrosity devoid of its original Arts and Crafts details. In fact, their second-floor addition will only bump up the roofline by 6 feet. "We don't want a big house; we're not going to gold-plate everything," says Michele. "We don't need fancy—we need functional."
  Along with the added bedrooms, the couple's other wish-list item is an updated kitchen that opens up onto an entertaining area. Walls will move or come down entirely to allow the couple to interact with friends and family while preparing food. "I love to cook, and I'm at the stove while I'm socializing," says Michael. They also plan to spend as much time outside in the mild weather, so they'll create a screened-in porch and make sure that the entertaining areas connect easily to the outdoors. "We like to live outside more than the average Texan," explains Michael. "We're fine not having the AC on."
  
  That energy-saving mentality is one reason for their desire for a green renovation, but it may be the local way of life that truly influenced them. Austin, a young, tech-company town and one of the fastest growing cities in America, is at the forefront of the green movement. The Austin Green Building Program, one of the oldest in the country, will rate the project for its use of eco-friendly materials. Photovoltaic cells on the roof, rainwater collection for irrigation, spray-foam insulation, recycled-glass tile and countertops, and formaldehyde-free wood composites are just some of the resource-saving strategies and eco-friendly materials planned for the project.
  
  Overseeing it all will be architect David Webber and veteran green builder Bill Moore. With a budget of $250,000, they'll be working hard to incorporate the right materials and still accomplish the changes the couple need. The project will take less than five months overall, but when it's finished, Michael and Michele will have an updated version of their classic house, which they loved so much they couldn't part with it. "We did look at other, renovated houses in the neighborhood," says Michele. "But I feel responsible for this house. Houses have souls, and I need to take care of this one."
  
  
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TED Talks: Catherine Mohr presents green building and embodied energy

In this  short, funny, data-packed talk at TED U, Catherine Mohr walks through all the geeky decisions she made when building a green new house -- looking at real energy numbers, not hype. What choices matter most? Not the ones you think.

http://www.ted.com/talks/catherine_mohr_builds_green.html

Catherine Mohr began her career as an engineer, working for many years with Paul MacCready at AeroVironment to develop alternative-energy vehicles and high-altitude aircraft. Her midcareer break: medical school, where she invented a brilliantly simple device, the LapCap, that makes laproscopic surgeries safer.
Mohr now oversees the development of next-generation surgical robots and robotic procedures, as the director of medical research at Intuitive Surgical Inc., where she's the clinical design leader for the DaVinci Surgical Robotic system. She also works at Stanford's School of Medicine, where she studies simulation-based teaching methods to teach clinical skills to budding doctors. And she's a senior scientific advisor to the GlobalSolver Foundation, an innovative funding and study group that looks at ways to match up scientists and money to help the world's oceans.

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5 Ways You Can Lower Your Utility Bills This Summer

Excerpted from : thegoodhuman.com

May 01st, 2013

The easiest way to increase the amount of spare cash you have each month is by simply spending less. Now we can all cut down on our luxury items, or spend less on going for days out or meals with friends. But wouldn’t it be much better to cut down on the cost of your utility bills instead? Here are five ways you can lower your utility bills this summer.

1. Utilize Rain Barrels

Collecting rainwater from your roof and using it to water your garden will slash the amount of water consumption your household uses during the hot summer months. During the growing season, homeowners can save around 1,300 gallons of water, which adds up to a large amount on the water bill. Just half an inch of water is often enough to fill a 50-gallon rain barrel. If you install a few of these barrels, you may not need to turn the main tap on all year.

2. Plant Trees in Your Garden
Planting trees to the south and west of your house can lower energy consumption by around 5% in the summertime due to the shade it provided on the house. The bigger the trees the better, as they provide more shade for the house.

3. Use Solar Shades

If your home has lots of south-facing windows, the solar energy entering your home could be dramatically heating the property and costing you money to try and keep it cool again. Solar shades are a low-cost, effective way to reduce the amount of heat entering your home, and this will dramatically lower your electricity bill as you will not have to use fans or air conditioning nearly as much.

4. Keep it Clean

If you’re using an air conditioning unit, it’s essential that you carry out a monthly maintenance routine in order to keep the filters clean and the system working efficiently. A blocked filter can cost you money as the machine is not working as effectively as it could. Also, keeping your house clean tidy, and clutter free will increase the airflow around the property which also helps to lower the cost of cooling.

5. Alter Your Diet

During the summer months when you spend all day trying to keep the house cool, putting the oven on for hours at a time to cook your dinner or bake a cake is simply counter-productive. This can cause a huge temperature rise in your home and will cost more money to keep the temperature low during this time. Either cut down on your oven use and eat more salads and cool foods, or shut the kitchen door so that you are only heating one room.
Each of these simple steps may only make a small difference to the cost of your utility bills over the summer. If you make a lot of new habits over the coming months, trying to reduce energy consumption in lots of different ways, you will notice the reduction in your bills.

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What Are Solar Roof Shingles?

April 01st, 2013

EarthTalk is written and edited by Roddy Scheer and Doug Moss and is a registered trademark of E The Environmental Magazine (www.emagazine.com).

Q: I’m getting my roof redone and have heard about solar roof shingles. Are they available—and are they practical for the Northeast?

Solar shingles are photovoltaic cells designed to look like and integrate with conventional asphalt roof shingles. First commercially available in 2005, solar shingles were much more costly than traditional “bolt-on” photovoltaic panels, and thus were used mainly by those wanting to go solar but maintain a traditional roofline. But more recently solar shingles have become price-competitive with bolt-on panels, and are getting much more popular accordingly. Eco-conscious home and building owners might find solar shingles especially attractive when they are re-shingling anyway since the solar shingles also double as functional, protective and weatherproof roof shingles in their own right.

The biggest name in solar shingles is Dow’s Powerhouse line, which uses cutting edge Copper Indium Gallium Selenide solar cells (aka “thin-film” solar) to turn sunlight into electricity via a supplied inverter box. The Powerhouse shingles generate 12 watts per square foot and are “grid-tied,” meaning they’re designed for structures already connected to the power grid and can send excess power back to the grid. They are wireless, snap together and can be installed by regular roofing contractors just like (or alongside) conventional asphalt shingles (an electrician needs to set up the inverter box).

Dow reports that a typical residential cluster of 350 solar singles on a roof could slash one’s household electric bill by 40-60 percent. Such an installation can cost a homeowner over $20,000, but federal, state and local incentives can bring the cost to half that in some areas. Powerhouse shingles are currently available (from Dow-authorized contractors) in California, Colorado, Connecticut, Louisiana, Maryland, Massachusetts, Michigan, New York, North Carolina, Texas and Washington, D.C.

Another leader in solar shingles is building products manufacturer CertainTeed. The company’s Apollo line of grid-tied monocrystalline solar shingles and roofing tiles offers efficiency similar to larger “bolt-on” photovoltaic arrays at around the same price (and incentives similar to those for Dow may also apply) but with less bulk: Each Apollo tile is less than an inch thick and will integrate with, replace, or lay on top of existing asphalt roof shingles or tiles and generate 12 watts of power per square foot.

CertainTeed says a typical installation will save homeowners 40-70 percent on their electric bills. Their Apollo products are available across the U.S. but the company recommends using one of their authorized roofing contractors to make sure they are installed properly.

Now is an especially good time to go solar—shingles or otherwise—because costs have started to come down and the federal government is still offering 30 percent tax credits with no cap on the purchase of solar electricity equipment. Twenty-seven states and several cities offer additional incentives that can get pricing on solar gear and installations down even lower. For more information check out the Database of State Incentives for Renewables and Efficiency (DSIRE), a free online resource provided by the North Carolina Solar Center and IREC with funding from the U.S. Department of Energy.

Send questions to: earthtalk@emagazine.com. Subscribe:www.emagazine.com/subscribe; Free Trial Issue: www.emagazine.com/trial.

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Amory Lovins, 50 Year Energy Authority

Amory B. Lovins, a 65-year-old American consultant, experimental physicist and 1993 MacArthur Fellow, has been active at the nexus of energy, resources, environment, development, and security in more than 50 countries for 35 years, including 14 years based in England. He is widely considered among the world’s leading authorities on energy—especially its efficient use and sustainable supply—and a fertile innovator in integrative design.

After two years at Harvard, Mr. Lovins transferred to Oxford, and two years later became a don at 21, receiving in consequence an Oxford MA by Special Resolution (1971) and, later, 11 honorary doctorates of various U.S. and U.K. universities. He has been Regents’ Lecturer at the U. of California both in Energy and Resources and in Economics; Grauer Lecturer at UBC; Luce Visiting Professor at Dartmouth; Distinguished Visiting Professor at the University of Colorado; Oikos Visiting Professor of Business, U. of St. Gallen; an engineering visiting professor at Peking U.; and 2007 MAP/Ming Professor at Stanford’s School of Engineering.

During 1979–2002, Mr. Lovins worked as a team with Hunter Lovins (his wife 1979–99). They shared a 1982 Mitchell Prize, a 1983 Right Livelihood Award (often called the “alternative Nobel Prize”), the 1999 Lindbergh Award, and Time’s 2000 Heroes for the Planet Award. In 1989 he won the Onassis Foundation’s first Delphi Prize, one of the world’s top environmental awards, for their “essential contribution towards finding alternative solutions to energy problems.” That contribution included the “end-use / least-cost” redefinition of the energy problem (in Foreign Affairs in 1976)—asking what quantity, quality, scale, and source of energy will do each task in the cheapest way. This economically based approach first permitted successful foresight in the competitive energy-service marketplace.

In 1993 he received the Nissan Prize for inventing superefficient ultralight-hybrid cars, to which ~$10 billion had been committed by 2000, and in 1999, partly for that work, the World Technology Award (Environment). He also received the 1997 Heinz Award, the 2000 Happold Medal of the [UK] Construction Industry Council, the 2005 Benjamin Franklin Medal of the [UK] Royal Society of Arts (Life Fellow), and in 2007, the Blue Planet Prize, Volvo Prize, honorary membership of the American Institute of Architects, Foreign Membership of the Royal Swedish Academy of Engineering Sciences, Time International’s Hero of the Environment award, Popular Mechanics’ Breakthrough Leadership award, and honorary Senior Fellowship of the Design Futures Council. In 2008 he was named one of America’s 24 Best Leaders by U.S. News & World Report and Harvard’s Kennedy School, and received the first Aspen Institute / National Geographic Energy and Environment Award for Individual Thought Leadership. In 2009, he received the National Design Award (Design Mind), Time named him among the world’s 100 most influential people, and Foreign Policy, one of the 100 top global thinkers. In 2010, he was Runner-Up for the Zayed Future Energy Prize.

In 1982, the Lovinses cofounded Rocky Mountain Institute, an independent, entrepreneurial, nonprofit think-and-do tank. RMI’s ~80 staff drive the efficient and restorative use of resources to help create a world thriving, verdant, and secure, for all, for ever. Ms. Lovins left RMI in 2002; Mr. Lovins is now RMI's Chairman and Chief Scientist. The Institute’s ~$13-million annual revenue comes from programmatic enterprise, chiefly private-sector consultancy, and from grants and donations. RMI’s balance sheet comes largely from Mr. Lovins’s having cofounded, led, spun off, and in 1999 sold (to the Financial Times group), E Source, the premier source of information on advanced electric efficiency.

Mr. Lovins led the energy design for his home (and RMI’s original headquarters), whose ~99% savings in space- and water-heating energy (to –44°C or –47°F) and ~90% in home electricity paid back in ten months with 1983 technology. An $18-million utility experiment he cofounded and -steered in the 1990s, PG&E’s “ACT²,” validated his claim that very large energy savings could cost less than small or no savings, e.g. in houses comfortable with no air conditioner at up to +46ºC (+115°F) yet costing less to build. He founded and until 2007 chaired RMI’s fourth spinoff, the advanced-composites technology developer Fiberforge Corporation, and is RMI’s lead practitioner—lately helping redesign >$30 billion worth of facilities in 29 sectors—in implementing for major firms the tenets of natural capitalism, which shared the 2001 Shingo Prize (Research), the “Nobel Prize for Manufacturing.” In 2004, he led a Pentagon-cosponsored synthesis of how to eliminate U.S. oil use, led by business for profit, and in 2007, became the first member of the Transformation Advisory Council for the Executive Chairman of Ford Motor Company. His other senior advisory relationships have lately served the leaders of Coca-Cola, Deutsche Bank, Holcim, Interface, and Wal-Mart and of several startup firms.

Mr. Lovins’s other clients have included Accenture, Allstate, AMD, Anglo American, Anheuser-Busch, Bank of America, Baxter, Borg-Warner, BP, HP Bulmer, Carrier, Chevron, Ciba-Geigy, CLSA, ConocoPhillips, Corning, Dow, Equitable, GM, HP, Invensys, Lockheed Martin, Mitsubishi, Monsanto, Motorola, Norsk Hydro, Petrobras, Prudential, Rio Tinto, Royal Dutch/Shell, Shearson Lehman Amex, STMicroelectronics, Sun Oil, Suncor, Texas Instruments, UBS, Unilever, Westinghouse, Xerox, major developers, and over 100 energy utilities. His public-sector clients have included the OECD, the UN, and RFF; the Australian, Canadian, Dutch, German, and Italian governments; 13 states; Congress; and the U.S. Energy and Defense Departments.

Mr. Lovins has briefed 21 heads of state, given expert testimony in eight countries and 20+ states, delivered thousands of lectures, and written 31 books and more than 450 papers, as well as poetry, landscape photography, music (he was a pianist and composer), and an electronics patent. In 1980–81 he served on the U.S. Department of Energy’s senior advisory board, and in 1999–2001 and 2006–08, on Defense Science Board task forces on military energy strategy. In 1984 he was elected a Fellow of the American Association for the Advancement of Science “for his book Soft Energy Paths and many other noteworthy contributions to energy policy,” in 1988, of the World Academy of Arts and Sciences, and in 2001, of the World Business Academy. Dr. Alvin Weinberg, former Director of Oak Ridge National Laboratory, called him “surely the most articulate writer on energy in the whole world today; "Newsweek, "one of the Western world’s most influential energy thinkers.” Dr. John Ahearne, then Vice President of Resources for the Future, remarked that “Amory Lovins has done more to assemble and advance understanding of [energy] efficiency opportunities than any other single person.” The Centennial Issue of The Wall Street Journal named him among 39 people in the world most likely to change the course of business in the 1990s; Car called him the 22nd most powerful person in the global car industry; and The Economist wrote in 2008 that “history has proved him right.”

An occasional advisor to the National Association of Regulatory Utility Commissioners, World Business Council for Sustainable Development, and Kleiner Perkins Caufield & Byers, Mr. Lovins has addressed hundreds of fora sponsored by such groups as The Engineering Foundation, Association of Energy Engineers, ASHRAE, Society of Automotive Engineers, Royal Academy of Engineering, National Academy of Sciences, American Physical Society, International Association for Energy Economics, Montreux Energy Forum, Institution of Electrical Engineers, McKinsey, Accenture, Merrill Lynch, JPMorgan, Allen & Co., News Corporation, Fortune, Forbes, Time, ULI, IDRC, CoreNet, AIA, API, AAPG, AGA, EEI, EPRI, CRIEPI, Hoover and Brookings Institutions, CSIS, Chatham House, Council on Foreign Relations, Pacific Council, Commonwealth Club, Keidanren, Conference Board, World Economic Forum, Tällberg Conference, TED, FiRE, eg, World Bank, GBN, Highlands Forum, NPS, NWC, NDU, DAU, Aspen Design Conference, Royal Society, and Royal Society of Arts. He collaborates on landscape photography and orangutan conservation with his wife, fine-art landscape photographer Judy Hill Lovins (www.judyhill.com).

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INTERVIEW: Building Science Pioneer Dr. Joe Lstiburek on the Good, Bad and Ugly Side of Buildings

Posted By Andrew Michler On March 11, 2013 @ 12:05 am In Architecture,Interviews,Sustainable Building 

The term ‘building science’ is used quite often now in sustainable building circles, but much of what we understand of it can be traced back to the work of Dr. Joe Lstiburek ^[4], founder ofBuilding Science Corporation ^[5]. He is anything but your typical engineer ^[6] or scientist who spends time crunching numbers or hiding away in a lab. Lstiburek has spent most of his career out in the field, testing and examining what works and what doesn’t. Many of the building standards today — from building codes to ASHRE to testing methodology — have his finger prints all over them, and his tough love criticism of building design is undercut with his wry humor and, of course, an encyclopedic knowledge of building construction. Read on to learn where buildings go wrong and what we can do about it.

Inhabitat: What does building science really mean? Did it not exist 50 years ago?

Joe Lstiburek: Well, it always existed. It’s really the technical side of architecture ^[7] that architects gave up. If architects did their job there wouldn’t be any need for building science. You know, I’m flabbergasted by the architectural profession giving up control of such a profitable part of the industry, which is the interaction of the building enclosure with the climate and the people and the mechanical system.

You know, this occurred because of the change in the focus on the education of the architects, the school. They’re focused – they’re trained in art. They’re not trained in physics and material science to actually execute their designs.

Back in the day, 100 years ago, or maybe 50 years ago in Europe, architects were trained like master builders. They understood structure. They understood mechanical. They understood physics. They understood material science. They understood how everything worked together. The focus now on the architectural education is all art and what’s missing are all of those other pieces — one of those missing pieces is building science or building physics.

Inhabitat: Do they feel like it’s not their problem? Such as how a building envelope will necessarily function in the real world — that if it’s down on paper and it’s been done before, then that’s okay?

Joe Lstiburek: I can’t speak for the architectural community, although I often try to – that is I think the arrogance of the profession drives me crazy. I think they feel it’s beneath their dignity to worry about these little, minor problems, like how to keep the rain out of the building, how to keep the air in and the air out. Let somebody else worry about that. I’m here to make an uplifting building to society to basically send a message about how this building is going to make this place a better place to live, and the people that live and work in it are better people. That’s what my mission is. This other stuff somebody else will worry about.

Inhabitat: So how do you get them excited about building science again?

Joe Lstiburek: Well, I don’t. What happens is the legal profession does that for us. The most effective technology transfer in the world is a lawsuit. They never call us when things are going well. They call us, “Oh, my God! We’re getting our ass sued because this problem occurred.” 

Inhabitat: One of my favorite things you  talk about is how highrises eighty years ago were more energy efficient than just about anything built today, especially with curtain walls and glass.

Joe Lstiburek: Well, it’s real easy. It’s just glass. I mean we have glass boxes and glass and steel are inefficient. Back in the day we had glazing ratios that were 10 and 15 percent and mass walls. An R2 curtain wall can’t compare to an R8 mass wall assembly. It’s not even close.

Inhabitat: So we talk about these advanced materials, advanced glazing options we have now and, you know, they go on and on and on. They are still nothing compared to a masonry wall as far as energy efficiency?

Joe Lstiburek: They’re nothing to the old approaches, but in the last 50 years the architectural profession has managed to piss away every energy advance that the rest of us have made because of all of the glass. I mean it’s just amazing to me.

And the hypocrisy is stunning. They blame everything. We’re here to save the planet. We’re here because it’s real important for our carbon footprint. And yet they turn out one glass box after another glass box after another glass box and they’re interested in what the emission rate of the paint is, and what the embodied energy of the carpet is, and the biggest problem is their original design. That just drives me crazy. LEED ^[8] is a colossal joke for that reason. They equate a bike rack with the same efficiency as the enclosure.

Inhabitat: Everybody who wants to point LEED’s weakness uses the bike rack argument.

Joe Lstiburek: Guess what? For good reason. And you know what? They’re idiots to do that and they refuse to limit glazing ratios and they don’t measure s***.

Inhabitat: And there’s no commissioning of the envelope.

Joe Lstiburek: No. It’s crazy, and you know what? We’ve been collecting the numbers and they’re pathetic. What’s great is that, okay, now they’re going to fix it, nothing like taking a really flawed and screwed up program and having to fix it.

Well, the lawsuit that Gifford started ^[9] gave them a wake-up call. The fact that people are now publishing the results and they’re pretty poor has given a wake-up call. At the end of the day, LEED is going to get fixed because they have no choice. It’s just that we’ve wasted a decade.

Inhabitat: It wasn’t just that lawsuit. You really started harping on how weak the LEED energy and atmosphere credits were in 2008.

Joe Lstiburek: I couldn’t understand why a licensed engineer or a licensed architect would have an outside bunch with a checklist supplement their professional knowledge and experience. I mean how insulting is that? Because that tells me that you are so poor as a professional that you believe that the judgment of a third-party checklist is more significant than your knowledge.

And experience as an architect or engineer. Are you kidding me? I mean I would have thrown them out of my office. I would have said, “What? Get the hell out of here.”

You go and you do this checklist thing and you’re telling me that I have to superimpose this arbitrarian, capricious checklist on my skill as an architect, as an engineer. I mean that, to me, is flabbergasting.

Inhabitat: So is it the same effect of when architects gave up the idea of building science and said somebody else can worry about it. The LEED checklist gave the architects the opportunity for somebody else to worry about what green building really is?

Joe Lstiburek: The architects have caused their own problem and only the architects can solve their own problem and I have faith that the architectural profession will fix itself. Architects need to get in charge of the process again, totally in charge of the process, and for that they need the education and the experience to do that.

There should be no reason that we have all of these outside consultants that are sucking bits of the architectural key out of the process. The architects should grab that for themselves and deliver the whole building the right way, to be the boss of the job, to be the master builders again. I mean my daughter is an architect and I keep telling them, “Your generation has to fix this. You guys need to be in charge again.”

Inhabitat: We talked about the curtain wall or glass being a key concern of energy efficiency in buildings. What else is a major issue right now?

Joe Lstiburek: In my view, over-ventilation.

Inhabitat: Is that ASHRAE’s fault or just people are doing above and beyond?

Joe Lstiburek: Well, ASHRAE is dominated by a vested interest in politics and LEED is even worse, if you can imagine that. I mean could you imagine getting a LEED point for increasing the ventilation 30 percent above ASHRAE and ASHRAE’s is already out of control.

The answer is source control, dilution is not the solution to indoor pollution and increasing ventilation rates is a horrible problem. The right way to do it is to not have the contaminant built into the building in the first place. And despite all of the people saying that there’s a clear link between certain levels of contaminants and medical effects, the epidemiology hasn’t been done.

People claim that it’s been done, but believe it or not, we don’t have the information in houses. We don’t know what the contaminants are. They have not been measured carefully and we’re making national policy decisions on ventilation going blind, with a bunch of people just getting together and offering an opinion. And the opinion is based on which political faction has managed to stack the ASHRE committee with their dominant voting block.

That’s not the way to do this. I mean you’d think with the amount of energy that buildings consume, and the amount of energy that residential buildings consume, that maybe somebody, like the federal government, would actually fund a study. You would need $20 million or $30 million and to go around and measure a whole slew of things in houses. That’s not been done, but yet, changing the ventilation rate by 15 or 20 percent is going to have more than that impact cost-wise on energy within the first year.

This kind of stuff drives me crazy. They manage to piss away money on stupid s*** and they can’t seem to fund something that’s important.

And the same thing in commercial buildings. You know, people are claiming that this level of formaldehyde ^[10] is dangerous and this level isn’t. What’s all of this based on? I mean most of the limits and for indoor air in buildings we’re simply taking occupational numbers and dividing by ten. Why not dividing by 12? Why not dividing by 15? In California, because California is crazy on every conceivable level, they divide by 100 ^[11]. So, in one state the occupational number because the indoor number by dividing by ten and California divided by 100. If people knew how arbitrary and capricious this was they’d go, “Well, you’re kidding me.”

Inhabitat: Is California basing their numbers on European models?

Joe Lstiburek: No. It wasn’t based on any models. What’s amazing is formaldehyde in houses doesn’t respond to ventilation rate changes. So if you’re ventilating at 0.1 versus 0.2 versus 0.3, the formaldehyde concentration remains constant. The reason is the more you ventilate the more it emits. You ventilate less it emits less. Don’t put it in the building, that’s a phenomenally successful way of dealing with the problem.

I’ll give you another example, which will never happen, but late at night I dream about it — have you’ve heard of the MSDS sheets?

Inhabitat: Sure.

Joe Lstiburek: They tell you absolutely nothing. What people think that the MSDS sheets tells us is what the manufacturer puts in their product. The answer is no. That would be useful if they told us everything that went into this product and the quantities, but that’s viewed as a trade secret.

What the MSDS sheet tells us is that if you put this into the product, you have to tell us that it’s in the product and this comes from a very short list of “this’es”. In other words, in order to get on that short list it takes a lot of effort. It really has to be miserable and beyond a shadow of a doubt, bad. So there’s a very short list of what you have to notify.

What that means is that people are idiots to take anything from that list, to put it in there. So they use a whole bunch of other things that nobody knows anything about or haven’t made it to the list, but they don’t have to tell you about it.  I always laugh –LEED and other people want you get to the MSDS sheet – and I’m saying “Why?”  What you need to do is you need to take one of the guys who makes this stuff out to dinner, get him drunk, and ask him: “What’s in there?”

Inhabitat: Another study funding opportunity for the U.S. government?

Joe Lstiburek: Well, not funding – basically, change the law. Make them tell us what’s in their products.

Inhabitat: So that regulation would make complete sense?

Joe Lstiburek: Phenomenal sense. Tell us what’s in it.

Inhabitat: Let’s get back to energy a little bit. Is thermal bridging the next cusp of people’s thinking about how building envelopes work?

Joe Lstiburek: Well, it’s no mystery to anybody who knows about buildings that it’s a big deal. I’m kind of amused that people are just figuring out well, glass is really bad and there’s too much it. Not having insulation continuously is a big deal.

What’s even more important is that air tightness is even more important. There’s no requirement for air tightness. How can you with a straight face talk about energy efficiency and not have a requirement for air tightness?

Inhabitat: How would you test for air tightness in a large building?

Joe Lstiburek: It’s easy. Every building has a mechanical system. You just simply open all of the interior doors and turn on the exhaust fan and measure the pressure difference, then close the exhaust fan and turn on the supply fan and measure the pressure difference. You got your entire building leakage.

You don’t even need to do it that way. Just simply take a compartment and measure the pressure in the compartment. You don’t have to measure the whole building, just measure pieces of the building. There are a lot of ways to do this.

I wrote about it in Understanding Air Barriers ^[12] on our web site and actually did my doctoral dissertation on how some of this can be done. It’s just that it takes about a half a day to set up the test and about 15 minutes to run the test. For people that claim that this is complicated and hard, it’s just not hard.

The problem is that because it is easy to do, and if you actually do it and you create a performance requirement, people will have to meet that requirement. That means they’re going to have to change what they do and that’s what the problem is; people don’t want to change what they do.

Inhabitat: You have been successful in taking complex building dynamics and making them relatively simple to understand. Do you think that building science is less complicated than a lot of folks out there are making it sound with a lot of hemming and hawing?

Joe Lstiburek: It’s a lot less complicated than people say and my only observation is there’s a lot of money to be made in keeping the peasants confused. I mean it’s so easy. What drives me crazy is WUFI models and computer simulations. None of that is necessary, and most of it is done wrong anyway.

I spend most of my time, and my firm spends a lot of time debunking other people’s reports, saying, “You can’t possibly be saying this based on what you did. The problem is the wall is leaking because you don’t have a flashing. Your hygrothermal model has nothing to do with why this wall is wet.”

Inhabitat: They couldn’t see the trees for the forest.

Joe Lstiburek: They couldn’t see the water through the trees.

Inhabitat: There you go. It sounds like, especially when we start talking about air barriers, you just do that right than you solve a lot of the other problems. You made a good living on buildings having lots of moisture issues.

Joe Lstiburek: It’s been a hell of a good life. I get to spend the entire winter in Aspen. Are you kidding me? The key to spending your entire winter in Aspen is to find a woman to love and marry, stay married to her, and get into fixing buildings. You need both.

Inhabitat: Good advice for the upcoming engineers who read this. So what’s the take away? Is it that air barriers are the biggest thing we need to focus on?

Joe Lstiburek: Well, no. Look, if I was in charge of teaching architects building science becomes very simple ^[13]. Building enclosure is an environmental separator. You want to keep the outside out and the inside in, except when you want to bring the outside in and when you want to have the inside out. That’s it and there are certain rules on how to do that.

I have this little list of rules and it all can be distilled into we need a water controlled barrier, an air controlled barrier, a vapor controlled barrier, and a thermal controlled barrier. Then we need a method of exchanging the inside with the outside based on when we want to. That’s it, there are sub-rules on how you do this, but that’s fundamentally it.

And I would have loved to written my own LEED standard. It would have been a paragraph long and it would start off by saying, “Don’t do stupid things,” and, “Do this,” and we’re done. “And measure everything,” because if you can’t measure it, I don’t believe it.

Inhabitat: Are we looking at a climate specific design?

Joe Lstiburek: Oh, I don’t believe that. The wall-roof foundation assembly that I laid out works everywhere.

If you are doing poor assemblies you have to be very careful climatically, but a good assembly works everywhere. The irony is that the crappy assemblies are very climatically sensitive. The good assemblies are climatically robust.

Inhabitat: So, does that mean state-of-the art is that we can find wall systems that can be translated to work in almost any situation.

Joe Lstiburek: I have a little bit of fun with this. I teach at the university now and I no longer fail stupid students because that would be discriminating against stupid students. I say, “Look, I have to pass you. You’re an idiot. I can’t fail you, but I’ll make a deal. Promise me this – that regardless of where you end up and how long you practice, you’re only going to use this wall design, and this roof design, and this foundation design, because they work everywhere.”

Inhabitat: And forever.

Joe Lstiburek: And forever. Quite frankly, that is true.

Inhabitat: So you feel confident that building science is at the point now that we can build a quality envelope that we’ll feel comfortable with 40 years from now. We go back, we tear that thing up, we’ll feel that everything’s done what it needs to?

Joe Lstiburek: Oh, we were able to do that 50, 60 years ago. The answer is yes, we’re able to do that now and we were able to do that before I was born. The irony is that even though that information has been known for so long, it’s not been used. And my observation on that is that people don’t use stuff until it becomes impossible for them to not use it. In other words, things become intolerably bad before there’s a change or an intervention. It’s only recently that things are becoming intolerably bad enough that we have to intervene and fix, even though we knew or some folks knew how to avoid the problems 50 or 60 years ago.

None of this is very complicated, none of this is a big mystery. What’s happening now is that we need to get this information into the people who need to make the decisions in an informed matter. In other words, people aren’t inherently bad. They just don’t have the information they need at the right time to make the right decision. So this is an information issue as opposed to a research issue. We don’t need to do anymore research. We need to do better transfer of what we know to the people who need to make the decisions at the right time.

Inhabitat: So where is that information now? What are the sources for working professionals to tap into this in a meaningful way?

Joe Lstiburek: Well, NIBS, National Institute for Building Science ^[14] has got a group called BETEC ^[15] and they’ve got some phenomenal design stuff online. I mean I hate to brag, but our website BuildingScience.com ^[16] is pretty darn good. And it’s for free –actually not, you’ve already paid for it. A lot of that work came out of government contracts that we were paid to do.

The National Research Council of Canada ^[17] and Canada Mortgage and Housing Corporation ^[18] have fabulous information online. The Department of Energy ^[19], USDoE, has got phenomenally good information online. And by and large, it’s fairly consistent. There aren’t big differences and wherever there is a big difference, just agree with me.

Inhabitat: Very good.

Joe Lstiburek: That was a bit of humor there, but you’re not laughing.

Inhabitat: I’ll write, “Ha-ha,” in there.

Joe Lstiburek: The big questions have been answered consistently well by all of these groups and there are issues in the margins, but they’re not big issues.

Inhabitat: When you go on the DoE web site there’s like 400 links or something like that to the energy software available, energy modeling software, for instance. Now, is any of this stuff really –

Joe Lstiburek: Useful? No. No. No.

Inhabitat: Everybody is wishing to have that magic bullet software?

Joe Lstiburek: Well, I view it as in love with Star Trek. I blame it all on Star Trek. Spock could go into that shuttle bay with his tricorder, do a tricorder scan and figure out that the tachyon field was interfering with the dilythiam crystals, causing him to off-gas, which is why Uhura has a headache. F**k that. We can’t measure s**t like that, but we believe that we can measure everything.

Watch NCIS and Abby Sciuto, that babe in the lab – you know, freaking does magical things and measures s**t and she does it all in 45 minutes, not counting commercials. It’s that we couldn’t do in 20 years even if we had unlimited money and people think that you can simulate and measure stuff. The world is not that clean and neat.

The best way we learn all of this is to build it and you see what happened. You say, “Ah, this worked. This didn’t,” and that’s the best education or information. That information lies in the experience base of the older engineers, architects and contractors.

One of the biggest problems we have is what I call our own institutional memory. We do a lousy job in construction, engineering and architecture, passing on the lessons of one generation to the next. So we are this huge, dysfunctional family. We need a Dr. Phil to get us all to talk to one another, or an Oprah, or somebody.

Inhabitat: It’s amazing how many times you refer to the fact that you would hypothesize something, come up with it and find it – it was in the books in the ‘50s and the ‘40s and the ‘60s.

Joe Lstiburek: It’s funny. I am one of the most frustrated, egotistical engineers on the planet. I thought I was a clever, smart guy who figured out stuff and it turns out that nothing I’ve ever thought I figured out did I actually figure out. It had been already done – better, earlier, more elegantly by not just one person, by lots of people. And we’re having all of these same discussions and arguments over and over and over again.

You know what? I feel like Bill Murray in Groundhog’s Day, except I don’t have an Andie MacDowell.

Locate Sustainable Building Materials at WorldClassSupply

The What and  Why of Passive House (PassivHaus) Design in a nutshell according to Wikipedia.com…..

While some techniques and technologies were specifically developed for the Passive House standard, others, such as superinsulation, already existed, and the concept of passive solar building design dates back to antiquity.

Standards

The Passivhaus standard for central Europe requires that the building fulfills the following requirements:

• The building must be designed to have an annual heating demand as calculated with the Passivhaus Planning Package of not more than 15 kWh/m² per year (4746 btu/ft² per year) in heating and 15 kWh/m² per year cooling energy OR to be designed with a peak heat load of 10W/m²
• Total primary energy (source energy for electricity and etc.) consumption (primary energy for heating, hot water andelectricity) must not be more than 120 kWh/m² per year (3.79 × 10⁴ btu/ft² per year)
• The building must not leak more air than 0.6 times the house volume per hour (n₅₀ ≤ 0.6 / hour) at 50 Pa (N/m²) as tested by a blower door

Recommendations

• Further, the specific heat load for the heating source at design temperature is recommended, but not required, to be less than 10 W/m² (3.17 btu/h.ft² per hour).

These standards are much higher than houses built to most normal building codes. For comparisons, see the international comparisons section below.

National partners within the 'consortium for the Promotion of European Passive Houses' are thought to have some flexibility to adapt these limits locally.^[24]

Space heating requirement

By achieving the Passivhaus standards, qualified buildings are able to dispThe What and Why of Passive House (PassivHaus) Design in a nutshell according to Wikipedia.com…..

While some techniques and technologies were specifically developed for the Passive House standard, others, such as superinsulation, already existed, and the concept of passive solar building design dates back to antiquity. 

Standards

The Passivhaus standard for central Europe requires that the building fulfills the following requirements:

• The building must be designed to have an annual heating demand as calculated with the Passivhaus Planning Package of not more than 15 kWh/m² per year (4746 btu/ft² per year) in heating and 15 kWh/m² per year cooling energy OR to be designed with a peak heat load of 10W/m²

• Total primary energy (source energy for electricity and etc.) consumption (primary energy for heating, hot water andelectricity) must not be more than 120 kWh/m² per year (3.79 × 104 btu/ft² per year)

• The building must not leak more air than 0.6 times the house volume per hour (n50 ≤ 0.6 / hour) at 50 Pa (N/m²) as tested by a blower door

Recommendations

• Further, the specific heat load for the heating source at design temperature is recommended, but not required, to be less than 10 W/m² (3.17 btu/h.ft² per hour).

These standards are much higher than houses built to most normal building codes. For comparisons, see the international comparisons section below.

National partners within the 'consortium for the Promotion of European Passive Houses' are thought to have some flexibility to adapt these limits locally.[24]

Space heating requirement

By achieving the Passivhaus standards, qualified buildings are able to dispense with conventional heating systems. While this is an underlying objective of the Passivhaus standard, some type of heating will still be required and most Passivhaus buildings do include a system to provide supplemental space heating. This is normally distributed through the low-volume heat recovery ventilation system that is required to maintain air quality, rather than by a conventional hydronic or high-volume forced-air heating system, as described in the space heating section below.

Construction costs

In Passivhaus buildings, the cost savings from dispensing with the conventional heating system can be used to fund the upgrade of the building envelope and the heat recovery ventilation system. With careful design and increasing competition in the supply of the specifically designed Passivhaus building products, in Germany it is now possible to construct buildings for the same cost as those built to normal German building standards, as was done with the Passivhaus apartments at Vauban, Freiburg.[25]On average, however, passive houses are still up to 14% more expensive upfront than conventional buildings.[26]

Evaluations have indicated that while it is technically possible, the costs of meeting the Passivhaus standard increase significantly when building in Northern Europe above 60° latitude.[27][28] European cities at approximately 60° include Helsinki in Finland and Bergen in Norway. London is at 51°; Moscow is at 55°.

These facts have led a number of architects to construct buildings that use the ground under the building for massive heat storage to shift heat production from the winter to the summer. Some buildings can also shift cooling from the summer to the winter. At least one designer uses a passive thermosiphon carrying only air, so the process can be accomplished without expensive, unreliable machinery.[29] (See also Annualized geo solar)

Design and construction

The Passivhaus uses a combination oflow-energy building techniques and technologies.

Achieving the major decrease in heating energy consumption required by the standard involves a shift in approach to building design and construction. Design may be assisted by use of the 'Passivhaus Planning Package' (PHPP),[30] which uses specifically designed computer simulations.

To achieve the standards, a number of techniques and technologies are used in combination:[2]

Passive solar design and landscape

Passive solar building design and energy-efficient landscaping support the Passive house energy conservation and can integrate them into a neighborhood and environment. Following passive solar building techniques, where possible buildings are compact in shape to reduce their surface area, with principal windows oriented towards the equator - south in the northern hemisphere and north in the southern hemisphere - to maximize passive solar gain. However, the use of solar gain, especially in temperate climate regions, is secondary to minimizing the overall house energy requirements. In climates and regions needing to reduce excessive summer passive solar heat gain, whether from direct or reflected sources, Brise soleil, trees, attached pergolas with vines, vertical gardens, green roofs, and other techniques are implemented.

Passive houses can be constructed from dense or lightweight materials, but some internal thermal mass is normally incorporated to reduce summer peak temperatures, maintain stable winter temperatures, and prevent possible overheating in spring or autumn before the higher sun angle "shades" mid-day wall exposure and window penetration. Exterior wall color, when the surface allows choice, for reflection or absorption insolation qualities depends on the predominant year-round ambient outdoor temperature. The use of deciduous trees and wall trellised or self attaching vines can assist in climates not at the temperature extremes.

Superinsulation

Passivhaus buildings employ superinsulation to significantly reduce the heat transfer through the walls, roof and floor compared to conventional buildings.[31] A wide range ofthermal insulation materials can be used to provide the required high R-values (low U-values, typically in the 0.10 to 0.15 W/(m².K) range). Special attention is given to eliminating thermal bridges.

A disadvantage resulting from the thickness of wall insulation required is that, unless the external dimensions of the building can be enlarged to compensate, the internal floor area of the building may be less compared to traditional construction.

In Sweden, to achieve passive house standards, the insulation thickness would be 335 mm (about 13 in) (0.10 W/(m².K)) and the roof 500 mm (about 20 in) (U-value 0.066 W/(m².K)).

Advanced window technology

Typical Passive House windows

To meet the requirements of the Passivhaus standard, windows are manufactured with exceptionally high R-values (low U-values, typically 0.85 to 0.70 W/(m².K) for the entire window including the frame). These normally combine triple-paneinsulated glazing (with a good solar heat-gain coefficient,[2][31] low-emissivity coatings, sealed argon or krypton gas filled inter-pane voids, and 'warm edge' insulating glass spacers) with air-seals and specially developed thermally broken window frames.

In Central Europe and most of the United States, for unobstructed south-facing Passivhaus windows, the heat gains from the sun are, on average, greater than the heat losses, even in mid-winter.

Airtightness

Building envelopes under the Passivhaus standard are required to be extremely airtight compared to conventional construction. This is achieved through air barriers, careful sealing of every construction joint in the building envelope, and sealing of all service penetrations.[31]

Airtightness minimizes the amount of warm — or cool — air that can pass through the structure, enabling the mechanical ventilation system to recover the heat before discharging the air externally.[2]

Ventilation

Use of passive natural ventilation is an integral component of passive house design where ambient temperature is conducive — either by singular or cross ventilation; by a simple opening or enhanced by the stack effect from smaller ingress with larger egress windows and/or clerestory-operable skylight.

When ambient climate is not conducive, mechanical heat recovery ventilation systems, with a heat recovery rate of over 80% and high-efficiency electronically commutated motors (ECM), are employed to maintain air quality, and to recover sufficient heat to dispense with a conventional central heating system.[2] Since passively designed buildings are essentially air-tight, the rate of air change can be optimized and carefully controlled at about 0.4 air changes per hour. All ventilation ducts are insulated and sealed against leakage.

Some Passivhaus builders promote the use of earth warming tubes (typically ≈200 mm (~7,9 in) diameter, ≈40 m (~130 ft) long at a depth of ≈1.5 m (~5 ft)). These are buried in the soil to act as earth-to-air heat exchangers and pre-heat (or pre-cool) the intake air for the ventilation system. In cold weather the warmed air also prevents ice formation in the heat recovery system's heat exchanger. Concerns about this technique have arisen in some climates due to problems with condensation and mold.[32]

Alternatively, an earth to air heat exchanger can use a liquid circuit instead of an air circuit, with a heat exchanger (battery) on the supply air.

Space heating

Passivhaus: In addition to the heat exchanger (centre), a micro-heat pump extracts heat from the exhaust air (left) and hot water heats the ventilation air (right). The ability to control building temperature using only the normal volume of ventilation air is fundamental.

In addition to using passive solar gain, Passivhaus buildings make extensive use of their intrinsic heat from internal sources—such as waste heat from lighting, white goods (major appliances) and other electrical devices (but not dedicated heaters)—as well as body heat from the people and other animals inside the building. This is due to the fact that people, on average, emit heat equivalent to 100 watts each of radiated thermal energy.

Together with the comprehensive energy conservation measures taken, this means that a conventional central heatingsystem is not necessary, although they are sometimes installed due to client skepticism.[33]

Instead, Passive houses sometimes have a dual purpose 800 to 1,500 watt heating and/or cooling element integrated with the supply air duct of the ventilation system, for use during the coldest days. It is fundamental to the design that all the heat required can be transported by the normal low air volume required for ventilation. A maximum air temperature of 50 °C (122 °F) is applied, to prevent any possible smell of scorching from dust that escapes the filters in the system.

The air-heating element can be heated by a small heat pump, by direct solar thermal energy, annualized geothermal solar, or simply by a natural gas or oil burner. In some cases a micro-heat pump is used to extract additional heat from the exhaust ventilation air, using it to heat either the incoming air or the hot water storage tank. Small wood-burning stoves can also be used to heat the water tank, although care is required to ensure that the room in which stove is located does not overheat.

Beyond the recovery of heat by the heat recovery ventilation unit, a well designed Passive house in the European climate should not need any supplemental heat source if the heating load is kept under 10W/m².[34]

Because the heating capacity and the heating energy required by a passive house both are very low, the particular energy source selected has fewer financial implications than in a traditional building, although renewable energy sources are well suited to such low loads.

Lighting and electrical appliances

See also: Daylighting, Passive daylighting, Active daylighting, and Ecological footprint

To minimize the total primary energy consumption, the many passive and active daylighting techniques are the first daytime solution to employ. For low light level days, non-daylighted spaces, and nighttime; the use of creative-sustainable lighting design using low-energy sources such as 'standard voltage' compact fluorescent lamps and solid-state lighting with Light-emitting diode-LED lamps, organic light-emitting diodes, and PLED - polymer light-emitting diodes; and 'low voltage' electrical filament-Incandescent light bulbs, and compact Metal halide, Xenon and Halogen lamps, can be used.

Solar powered exterior circulation, security, and landscape lighting - with photovoltaic cells on each fixture or connecting to a central Solar panel system, are available forgardens and outdoor needs. Low voltage systems can be used for more controlled or independent illumination, while still using less electricity than conventional fixtures and lamps. Timers, motion detection and natural light operation sensors reduce energy consumption, and light pollution even further for a Passivhaus setting.

Appliance consumer products meeting independent energy efficiency testing and receiving Ecolabel certification marks for reduced electrical-'natural-gas' consumption and product manufacturing carbon emission labels are preferred for use in Passive houses. The ecolabel certification marks of Energy Star and EKOenergy are examples.

Traits of passive houses

Typically, passive houses feature:

• Fresh, clean air: Note that for the parameters tested, and provided the filters (minimum F6) are maintained, HEPA quality air is provided. 0.3 air changes per hour (ACH) are recommended, otherwise the air can become "stale" (excess CO2, flushing of indoor air pollutants) and any greater, excessively dry (less than 40% humidity). This implies careful selection of interior finishes and furnishings, to minimize indoor air pollution from VOC's (e.g., formaldehyde). This can be counteracted somewhat by opening a window for a very brief time, by plants, and by indoor fountains.

• Because of the high resistance to heat flow (high R-value insulation), there are no "outside walls" which are colder than other walls.

• Homogeneous interior temperature: it is impossible to have single rooms (e.g. the sleeping rooms) at a different temperature from the rest of the house. Note that the relatively high temperature of the sleeping areas is physiologically not considered desirable by some building scientists. Bedroom windows can be cracked open slightly to alleviate this when necessary.

• Slow temperature changes: with ventilation and heating systems switched off, a passive house typically loses less than 0.5 °C (1 °F) per day (in winter), stabilizing at around 15 °C (59 °F) in the central European climate.

• Quick return to normal temperature: opening windows or doors for a short time has only a limited effect; after aperatures are closed, the air very quickly returns to the "normal" temperature.

, others, such as superinsulation, already existed, and the concept of passive solar building design dates back to antiquity. 

[edit]Standards

The Passivhaus standard for central Europe requires that the building fulfills the following requirements:[22][23]

The building must be designed to have an annual heating demand as calculated with the Passivhaus Planning Package of not more than 15 kWh/m² per year (4746 btu/ft² per year) in heating and 15 kWh/m² per year cooling energy OR to be designed with a peak heat load of 10W/m²

Total primary energy (source energy for electricity and etc.) consumption (primary energy for heating, hot water and electricity) must not be more than 120 kWh/m² per year (3.79 × 104 btu/ft² per year)

The building must not leak more air than 0.6 times the house volume per hour (n50 ≤ 0.6 / hour) at 50 Pa (N/m²) as tested by a blower door

Recommendations

Further, the specific heat load for the heating source at design temperature is recommended, but not required, to be less than 10 W/m² (3.17 btu/h.ft² per hour).

These standards are much higher than houses built to most normal building codes. For comparisons, see the international comparisons section below.

National partners within the 'consortium for the Promotion of European Passive Houses' are thought to have some flexibility to adapt these limits locally.[24]

Space heating requirement

By achieving the Passivhaus standards, qualified buildings are able to dispense with conventional heating systems. While this is an underlying objective of the Passivhaus standard, some type of heating will still be required and most Passivhaus buildings do include a system to provide supplemental space heating. This is normally distributed through the low-volume heat recovery ventilation system that is required to maintain air quality, rather than by a conventional hydronic or high-volume forced-air heating system, as described in the space heating section below.

Construction costs

In Passivhaus buildings, the cost savings from dispensing with the conventional heating system can be used to fund the upgrade of the building envelope and the heat recovery ventilation system. With careful design and increasing competition in the supply of the specifically designed Passivhaus building products, in Germany it is now possible to construct buildings for the same cost as those built to normal German building standards, as was done with the Passivhaus apartments at Vauban, Freiburg.[25] On average, however, passive houses are still up to 14% more expensive upfront than conventional buildings.[26]

Evaluations have indicated that while it is technically possible, the costs of meeting the Passivhaus standard increase significantly when building in Northern Europe above 60° latitude.[27][28] European cities at approximately 60° include Helsinki in Finland and Bergen in Norway. London is at 51°; Moscow is at 55°.

These facts have led a number of architects to construct buildings that use the ground under the building for massive heat storage to shift heat production from the winter to the summer. Some buildings can also shift cooling from the summer to the winter. At least one designer uses a passive thermosiphon carrying only air, so the process can be accomplished without expensive, unreliable machinery.[29] (See also Annualized geo solar)

Design and construction

The Passivhaus uses a combination of low-energy building techniques and technologies.

Achieving the major decrease in heating energy consumption required by the standard involves a shift in approach to building design and construction. Design may be assisted by use of the 'Passivhaus Planning Package' (PHPP),[30] which uses specifically designed computer simulations.

To achieve the standards, a number of techniques and technologies are used in combination:[2]

Passive solar design and landscape

Passive solar building design and energy-efficient landscaping support the Passive house energy conservation and can integrate them into a neighborhood and environment. Following passive solar building techniques, where possible buildings are compact in shape to reduce their surface area, with principal windows oriented towards the equator - south in the northern hemisphere and north in the southern hemisphere - to maximize passive solar gain. However, the use of solar gain, especially in temperate climate regions, is secondary to minimizing the overall house energy requirements. In climates and regions needing to reduce excessive summer passive solar heat gain, whether from direct or reflected sources, trees, attached pergolas with vines, vertical gardens, green roofs, and other techniques are implemented.

Passive houses can be constructed from dense or lightweight materials, but some internal thermal mass is normally incorporated to reduce summer peak temperatures, maintain stable winter temperatures, and prevent possible overheating in spring or autumn before the higher sun angle "shades" mid-day wall exposure and window penetration. Exterior wall color, when the surface allows choice, for reflection or absorption insolation qualities depends on the predominant year-round ambient outdoor temperature. The use of deciduous trees and wall trellised or self attaching vines can assist in climates not at the temperature extremes.

Superinsulation

Passivhaus buildings employ superinsulation to significantly reduce the heat transfer through the walls, roof and floor compared to conventional buildings.[31] A wide range of thermal insulation materials can be used to provide the required high R-values (low U-values, typically in the 0.10 to 0.15 W/(m².K) range). Special attention is given to eliminating thermal bridges.

A disadvantage resulting from the thickness of wall insulation required is that, unless the external dimensions of the building can be enlarged to compensate, the internal floor area of the building may be less compared to traditional construction.

In Sweden, to achieve passive house standards, the insulation thickness would be 335 mm (about 13 in) (0.10 W/(m².K)) and the roof 500 mm (about 20 in) (U-value 0.066 W/(m².K)).

Advanced window technology

Typical Passive House windows

To meet the requirements of the Passivhaus standard, windows are manufactured with exceptionally high R-values (low U-values, typically 0.85 to 0.70 W/(m².K) for the entire window including the frame). These normally combine triple-pane insulated glazing (with a good solar heat-gain coefficient,[2][31] low-emissivity coatings, sealed argon or krypton gas filled inter-pane voids, and 'warm edge' insulating glass spacers) with air-seals and specially developed thermally broken window frames.

In Central Europe and most of the United States, for unobstructed south-facing Passivhaus windows, the heat gains from the sun are, on average, greater than the heat losses, even in mid-winter.

Airtightness

Building envelopes under the Passivhaus standard are required to be extremely airtight compared to conventional construction. This is achieved through air barriers, careful sealing of every construction joint in the building envelope, and sealing of all service penetrations.[31]

Airtightness minimizes the amount of warm — or cool — air that can pass through the structure, enabling the mechanical ventilation system to recover the heat before discharging the air externally.[2]

[edit]Ventilation

Use of passive natural ventilation is an integral component of passive house design where ambient temperature is conducive — either by singular or cross ventilation; by a simple opening or enhanced by the stack effect from smaller ingress with larger egress windows and/or clerestory-operable skylight.

When ambient climate is not conducive, mechanical heat recovery ventilation systems, with a heat recovery rate of over 80% and high-efficiency electronically commutated motors (ECM), are employed to maintain air quality, and to recover sufficient heat to dispense with a conventional central heating system.[2] Since passively designed buildings are essentially air-tight, the rate of air change can be optimized and carefully controlled at about 0.4 air changes per hour. All ventilation ducts are insulated and sealed against leakage.

Some Passivhaus builders promote the use of earth warming tubes (typically ≈200 mm (~7,9 in) diameter, ≈40 m (~130 ft) long at a depth of ≈1.5 m (~5 ft)). These are buried in the soil to act as earth-to-air heat exchangers and pre-heat (or pre-cool) the intake air for the ventilation system. In cold weather the warmed air also prevents ice formation in the heat recovery system's heat exchanger. Concerns about this technique have arisen in some climates due to problems with condensation and mold.[32]

Alternatively, an earth to air heat exchanger can use a liquid circuit instead of an air circuit, with a heat exchanger (battery) on the supply air.

Space heating

Passivhaus: In addition to the heat exchanger (centre), a micro-heat pump extracts heat from the exhaust air (left) and hot water heats the ventilation air (right). The ability to control building temperature using only the normal volume of ventilation air is fundamental.

In addition to using passive solar gain, Passivhaus buildings make extensive use of their intrinsic heat from internal sources—such as waste heat from lighting, white goods (major appliances) and other electrical devices (but not dedicated heaters)—as well as body heat from the people and other animals inside the building. This is due to the fact that people, on average, emit heat equivalent to 100 watts each of radiated thermal energy.

Together with the comprehensive energy conservation measures taken, this means that a conventional central heating system is not necessary, although they are sometimes installed due to client skepticism.[33]

Instead, Passive houses sometimes have a dual purpose 800 to 1,500 watt heating and/or cooling element integrated with the supply air duct of the ventilation system, for use during the coldest days. It is fundamental to the design that all the heat required can be transported by the normal low air volume required for ventilation. A maximum air temperature of 50 °C (122 °F) is applied, to prevent any possible smell of scorching from dust that escapes the filters in the system.

The air-heating element can be heated by a small heat pump, by direct solar thermal energy, annualized geothermal solar, or simply by a natural gas or oil burner. In some cases a micro-heat pump is used to extract additional heat from the exhaust ventilation air, using it to heat either the incoming air or the hot water storage tank. Small wood-burning stoves can also be used to heat the water tank, although care is required to ensure that the room in which stove is located does not overheat.

Beyond the recovery of heat by the heat recovery ventilation unit, a well designed Passive house in the European climate should not need any supplemental heat source if the heating load is kept under 10W/m².[34]

Because the heating capacity and the heating energy required by a passive house both are very low, the particular energy source selected has fewer financial implications than in a traditional building, although renewable energy sources are well suited to such low loads.

[edit]Lighting and electrical appliances

See also: Daylighting, Passive daylighting, Active daylighting, and Ecological footprint

To minimize the total primary energy consumption, the many passive and active daylighting techniques are the first daytime solution to employ. For low light level days, non-daylighted spaces, and nighttime; the use of creative-sustainable lighting design using low-energy sources such as 'standard voltage' compact fluorescent lamps and solid-state lighting with Light-emitting diode-LED lamps, organic light-emitting diodes, and PLED - polymer light-emitting diodes; and 'low voltage' electrical filament-Incandescent light bulbs, and compact Metal halide, Xenon and Halogen lamps, can be used.

Solar powered exterior circulation, security, and landscape lighting - with photovoltaic cells on each fixture or connecting to a central Solar panel system, are available for gardens and outdoor needs. Low voltage systems can be used for more controlled or independent illumination, while still using less electricity than conventional fixtures and lamps. Timers, motion detection and natural light operation sensors reduce energy consumption, and light pollution even further for a Passivhaus setting.

Appliance consumer products meeting independent energy efficiency testing and receiving Ecolabel certification marks for reduced electrical-'natural-gas' consumption and product manufacturing carbon emission labels are preferred for use in Passive houses. The ecolabel certification marks of Energy Star and EKOenergy are examples.

Traits of passive houses

Typically, passive houses feature:

Fresh, clean air: Note that for the parameters tested, and provided the filters (minimum F6) are maintained, HEPA quality air is provided. 0.3 air changes per hour (ACH) are recommended, otherwise the air can become "stale" (excess CO2, flushing of indoor air pollutants) and any greater, excessively dry (less than 40% humidity). This implies careful selection of interior finishes and furnishings, to minimize indoor air pollution from VOC's (e.g., formaldehyde). This can be counteracted somewhat by opening a window for a very brief time, by plants, and by indoor fountains.

Because of the high resistance to heat flow (high R-value insulation), there are no "outside walls" which are colder than other walls.

Homogeneous interior temperature: it is impossible to have single rooms (e.g. the sleeping rooms) at a different temperature from the rest of the house. Note that the relatively high temperature of the sleeping areas is physiologically not considered desirable by some building scientists. Bedroom windows can be cracked open slightly to alleviate this when necessary.

Slow temperature changes: with ventilation and heating systems switched off, a passive house typically loses less than 0.5 °C (1 °F) per day (in winter), stabilizing at around 15 °C (59 °F) in the central European climate.

Quick return to normal temperature: opening windows or doors for a short time has only a limited effect; after aperatures are closed, the air very quickly returns to the "normal" temperature.

Standards

The Passivhaus standard for central Europe requires that the building fulfills the following requirements:[22][23]

• The building must be designed to have an annual heating demand as calculated with the Passivhaus Planning Package of not more than 15 kWh/m² per year (4746 btu/ft² per year) in heating and 15 kWh/m² per year cooling energy OR to be designed with a peak heat load of 10W/m²

• Total primary energy (source energy for electricity and etc.) consumption (primary energy for heating, hot water andelectricity) must not be more than 120 kWh/m² per year (3.79 × 104 btu/ft² per year)

• The building must not leak more air than 0.6 times the house volume per hour (n50 ≤ 0.6 / hour) at 50 Pa (N/m²) as tested by a blower door

Recommendations

• Further, the specific heat load for the heating source at design temperature is recommended, but not required, to be less than 10 W/m² (3.17 btu/h.ft² per hour).

These standards are much higher than houses built to most normal building codes. For comparisons, see the international comparisons section below.

National partners within the 'consortium for the Promotion of European Passive Houses' are thought to have some flexibility to adapt these limits locally

Space heating requirement

By achieving the Passivhaus standards, qualified buildings are able to dispense with conventional heating systems. While this is an underlying objective of the Passivhaus standard, some type of heating will still be required and most Passivhaus buildings do include a system to provide supplemental space heating. This is normally distributed through the low-volume heat recovery ventilation system that is required to maintain air quality, rather than by a conventional hydronic or high-volume forced-air heating system, as described in the space heating section below.

Construction costs

In Passivhaus buildings, the cost savings from dispensing with the conventional heating system can be used to fund the upgrade of the building envelope and the heat recovery ventilation system. With careful design and increasing competition in the supply of the specifically designed Passivhaus building products, in Germany it is now possible to construct buildings for the same cost as those built to normal German building standards, as was done with the Passivhaus apartments at Vauban, Freiburg.[25]On average, however, passive houses are still up to 14% more expensive upfront than conventional buildings.[26]

Evaluations have indicated that while it is technically possible, the costs of meeting the Passivhaus standard increase significantly when building in Northern Europe above 60° latitude.[27][28] European cities at approximately 60° include Helsinki in Finland and Bergen in Norway. London is at 51°; Moscow is at 55°.

These facts have led a number of architects to construct buildings that use the ground under the building for massive heat storage to shift heat production from the winter to the summer. Some buildings can also shift cooling from the summer to the winter. At least one designer uses a passive thermosiphon carrying only air, so the process can be accomplished without expensive, unreliable machinery.[29] (See also Annualized geo solar

Design and construction

The Passivhaus uses a combination oflow-energy building techniques and technologies.

Achieving the major decrease in heating energy consumption required by the standard involves a shift in approach to building design and construction. Design may be assisted by use of the 'Passivhaus Planning Package' (PHPP),[30] which uses specifically designed computer simulations.

To achieve the standards, a number of techniques and technologies are used in combination

[Passive solar design and landscape

Passive solar building design and energy-efficient landscaping support the Passive house energy conservation and can integrate them into a neighborhood and environment. Following passive solar building techniques, where possible buildings are compact in shape to reduce their surface area, with principal windows oriented towards the equator - south in the northern hemisphere and north in the southern hemisphere - to maximize passive solar gain. However, the use of solar gain, especially in temperate climate regions, is secondary to minimizing the overall house energy requirements. In climates and regions needing to reduce excessive summer passive solar heat gain, whether from direct or reflected sources, Brise soleil, trees, attached pergolas with vines, vertical gardens, green roofs, and other techniques are implemented.

Passive houses can be constructed from dense or lightweight materials, but some internal thermal mass is normally incorporated to reduce summer peak temperatures, maintain stable winter temperatures, and prevent possible overheating in spring or autumn before the higher sun angle "shades" mid-day wall exposure and window penetration. Exterior wall color, when the surface allows choice, for reflection or absorption insolation qualities depends on the predominant year-round ambient outdoor temperature. The use of deciduous trees and wall trellised or self attaching vines can assist in climates not at the temperature extremes.

Superinsulation

Passivhaus buildings employ superinsulation to significantly reduce the heat transfer through the walls, roof and floor compared to conventional buildings.[31] A wide range ofthermal insulation materials can be used to provide the required high R-values (low U-values, typically in the 0.10 to 0.15 W/(m².K) range). Special attention is given to eliminating thermal bridges.

A disadvantage resulting from the thickness of wall insulation required is that, unless the external dimensions of the building can be enlarged to compensate, the internal floor area of the building may be less compared to traditional construction.

In Sweden, to achieve passive house standards, the insulation thickness would be 335 mm (about 13 in) (0.10 W/(m².K)) and the roof 500 mm (about 20 in) (U-value 0.066 W/(m².K)).

Advanced window technology

Typical Passive House windows

To meet the requirements of the Passivhaus standard, windows are manufactured with exceptionally high R-values (low U-values, typically 0.85 to 0.70 W/(m².K) for the entire window including the frame). These normally combine triple-paneinsulated glazing (with a good solar heat-gain coefficient,[2][31] low-emissivity coatings, sealed argon or krypton gas filled inter-pane voids, and 'warm edge' insulating glass spacers) with air-seals and specially developed thermally broken window frames.

In Central Europe and most of the United States, for unobstructed south-facing Passivhaus windows, the heat gains from the sun are, on average, greater than the heat losses, even in mid-winter.

Airtightness

Building envelopes under the Passivhaus standard are required to be extremely airtight compared to conventional construction. This is achieved through air barriers, careful sealing of every construction joint in the building envelope, and sealing of all service penetrations.[31]

Airtightness minimizes the amount of warm — or cool — air that can pass through the structure, enabling the mechanical ventilation system to recover the heat before discharging the air externally.[

Ventilation

Use of passive natural ventilation is an integral component of passive house design where ambient temperature is conducive — either by singular or cross ventilation; by a simple opening or enhanced by the stack effect from smaller ingress with larger egress windows and/or clerestory-operable skylight.

When ambient climate is not conducive, mechanical heat recovery ventilation systems, with a heat recovery rate of over 80% and high-efficiency electronically commutated motors (ECM), are employed to maintain air quality, and to recover sufficient heat to dispense with a conventional central heating system.[2] Since passively designed buildings are essentially air-tight, the rate of air change can be optimized and carefully controlled at about 0.4 air changes per hour. All ventilation ducts are insulated and sealed against leakage.

Some Passivhaus builders promote the use of earth warming tubes (typically ≈200 mm (~7,9 in) diameter, ≈40 m (~130 ft) long at a depth of ≈1.5 m (~5 ft)). These are buried in the soil to act as earth-to-air heat exchangers and pre-heat (or pre-cool) the intake air for the ventilation system. In cold weather the warmed air also prevents ice formation in the heat recovery system's heat exchanger. Concerns about this technique have arisen in some climates due to problems with condensation and mold.[32]

Alternatively, an earth to air heat exchanger can use a liquid circuit instead of an air circuit, with a heat exchanger (battery) on the supply air.

Space heating

Passivhaus: In addition to the heat exchanger (centre), a micro-heat pump extracts heat from the exhaust air (left) and hot water heats the ventilation air (right). The ability to control building temperature using only the normal volume of ventilation air is fundamental.

In addition to using passive solar gain, Passivhaus buildings make extensive use of their intrinsic heat from internal sources—such as waste heat from lighting, white goods (major appliances) and other electrical devices (but not dedicated heaters)—as well as body heat from the people and other animals inside the building. This is due to the fact that people, on average, emit heat equivalent to 100 watts each of radiated thermal energy.

Together with the comprehensive energy conservation measures taken, this means that a conventional central heatingsystem is not necessary, although they are sometimes installed due to client skepticism.[33]

Instead, Passive houses sometimes have a dual purpose 800 to 1,500 watt heating and/or cooling element integrated with the supply air duct of the ventilation system, for use during the coldest days. It is fundamental to the design that all the heat required can be transported by the normal low air volume required for ventilation. A maximum air temperature of 50 °C (122 °F) is applied, to prevent any possible smell of scorching from dust that escapes the filters in the system.

The air-heating element can be heated by a small heat pump, by direct solar thermal energy, annualized geothermal solar, or simply by a natural gas or oil burner. In some cases a micro-heat pump is used to extract additional heat from the exhaust ventilation air, using it to heat either the incoming air or the hot water storage tank. Small wood-burning stoves can also be used to heat the water tank, although care is required to ensure that the room in which stove is located does not overheat.

Beyond the recovery of heat by the heat recovery ventilation unit, a well designed Passive house in the European climate should not need any supplemental heat source if the heating load is kept under 10W/m².[34]

Because the heating capacity and the heating energy required by a passive house both are very low, the particular energy source selected has fewer financial implications than in a traditional building, although renewable energy sources are well suited to such low loads.

Lighting and electrical appliances

See also: Daylighting, Passive daylighting, Active daylighting, and Ecological footprint

To minimize the total primary energy consumption, the many passive and active daylighting techniques are the first daytime solution to employ. For low light level days, non-daylighted spaces, and nighttime; the use of creative-sustainable lighting design using low-energy sources such as 'standard voltage' compact fluorescent lamps and solid-state lighting with Light-emitting diode-LED lamps, organic light-emitting diodes, and PLED - polymer light-emitting diodes; and 'low voltage' electrical filament-Incandescent light bulbs, and compact Metal halide, Xenon and Halogen lamps, can be used.

Solar powered exterior circulation, security, and landscape lighting - with photovoltaic cells on each fixture or connecting to a central Solar panel system, are available forgardens and outdoor needs. Low voltage systems can be used for more controlled or independent illumination, while still using less electricity than conventional fixtures and lamps. Timers, motion detection and natural light operation sensors reduce energy consumption, and light pollution even further for a Passivhaus setting.

Appliance consumer products meeting independent energy efficiency testing and receiving Ecolabel certification marks for reduced electrical-'natural-gas' consumption and product manufacturing carbon emission labels are preferred for use in Passive houses. The ecolabel certification marks of Energy Star and EKOenergy are examples.

Traits of passive houses

Typically, passive houses feature:

• Fresh, clean air: Note that for the parameters tested, and provided the filters (minimum F6) are maintained, HEPA quality air is provided. 0.3 air changes per hour (ACH) are recommended, otherwise the air can become "stale" (excess CO2, flushing of indoor air pollutants) and any greater, excessively dry (less than 40% humidity). This implies careful selection of interior finishes and furnishings, to minimize indoor air pollution from VOC's (e.g., formaldehyde). This can be counteracted somewhat by opening a window for a very brief time, by plants, and by indoor fountains.

• Because of the high resistance to heat flow (high R-value insulation), there are no "outside walls" which are colder than other walls.

• Homogeneous interior temperature: it is impossible to have single rooms (e.g. the sleeping rooms) at a different temperature from the rest of the house. Note that the relatively high temperature of the sleeping areas is physiologically not considered desirable by some building scientists. Bedroom windows can be cracked open slightly to alleviate this when necessary.

• Slow temperature changes: with ventilation and heating systems switched off, a passive house typically loses less than 0.5 °C (1 °F) per day (in winter), stabilizing at around 15 °C (59 °F) in the central European climate.

• Quick return to normal temperature: opening windows or doors for a short time has only a limited effect; after aperatures are closed, the air very quickly returns to the "normal" temperature.

ense with conventional heating systems. While this is an underlying objective of the Passivhaus standard, some type of heating will still be required and most Passivhaus buildings do include a system to provide supplemental space heating. This is normally distributed through the low-volume heat recovery ventilation system that is required to maintain air quality, rather than by a conventional hydronic or high-volume forced-air heating system, as described in the space heating section below.

Construction costs

In Passivhaus buildings, the cost savings from dispensing with the conventional heating system can be used to fund the upgrade of the building envelope and the heat recovery ventilation system. With careful design and increasing competition in the supply of the specifically designed Passivhaus building products, in Germany it is now possible to construct buildings for the same cost as those built to normal German building standards, as was done with the Passivhaus apartments at Vauban, Freiburg.^[25]On average, however, passive houses are still up to 14% more expensive upfront than conventional buildings.^[26]

Evaluations have indicated that while it is technically possible, the costs of meeting the Passivhaus standard increase significantly when building in Northern Europe above 60° latitude.^[27][28] European cities at approximately 60° include Helsinki in Finland and Bergen in Norway. London is at 51°; Moscow is at 55°.

These facts have led a number of architects to construct buildings that use the ground under the building for massive heat storage to shift heat production from the winter to the summer. Some buildings can also shift cooling from the summer to the winter. At least one designer uses a passive thermosiphon carrying only air, so the process can be accomplished without expensive, unreliable machinery.^[29] (See also Annualized geo solar)

Design and construction

The Passivhaus uses a combination oflow-energy building techniques and technologies.

Achieving the major decrease in heating energy consumption required by the standard involves a shift in approach to building design and construction. Design may be assisted by use of the 'Passivhaus Planning Package' (PHPP),^[30] which uses specifically designed computer simulations.

To achieve the standards, a number of techniques and technologies are used in combination:^[2]

Passive solar design and landscape

Passive solar building design and energy-efficient landscaping support the Passive house energy conservation and can integrate them into a neighborhood and environment. Following passive solar building techniques, where possible buildings are compact in shape to reduce their surface area, with principal windows oriented towards the equator - south in the northern hemisphere and north in the southern hemisphere - to maximize passive solar gain. However, the use of solar gain, especially in temperate climate regions, is secondary to minimizing the overall house energy requirements. In climates and regions needing to reduce excessive summer passive solar heat gain, whether from direct or reflected sources, Brise soleil, trees, attached pergolas with vines, vertical gardens, green roofs, and other techniques are implemented.

Passive houses can be constructed from dense or lightweight materials, but some internal thermal mass is normally incorporated to reduce summer peak temperatures, maintain stable winter temperatures, and prevent possible overheating in spring or autumn before the higher sun angle "shades" mid-day wall exposure and window penetration. Exterior wall color, when the surface allows choice, for reflection or absorption insolation qualities depends on the predominant year-round ambient outdoor temperature. The use of deciduous trees and wall trellised or self attaching vines can assist in climates not at the temperature extremes.

Superinsulation

Passivhaus buildings employ superinsulation to significantly reduce the heat transfer through the walls, roof and floor compared to conventional buildings.^[31] A wide range ofthermal insulation materials can be used to provide the required high R-values (low U-values, typically in the 0.10 to 0.15 W/(m².K) range). Special attention is given to eliminating thermal bridges.

A disadvantage resulting from the thickness of wall insulation required is that, unless the external dimensions of the building can be enlarged to compensate, the internal floor area of the building may be less compared to traditional construction.

In Sweden, to achieve passive house standards, the insulation thickness would be 335 mm (about 13 in) (0.10 W/(m².K)) and the roof 500 mm (about 20 in) (U-value 0.066 W/(m².K)).

Advanced window technology

Typical Passive House windows

To meet the requirements of the Passivhaus standard, windows are manufactured with exceptionally high R-values (low U-values, typically 0.85 to 0.70 W/(m².K) for the entire window including the frame). These normally combine triple-paneinsulated glazing (with a good solar heat-gain coefficient,^[2][31] low-emissivity coatings, sealed argon or krypton gas filled inter-pane voids, and 'warm edge' insulating glass spacers) with air-seals and specially developed thermally broken window frames.

In Central Europe and most of the United States, for unobstructed south-facing Passivhaus windows, the heat gains from the sun are, on average, greater than the heat losses, even in mid-winter.

Airtightness

Building envelopes under the Passivhaus standard are required to be extremely airtight compared to conventional construction. This is achieved through air barriers, careful sealing of every construction joint in the building envelope, and sealing of all service penetrations.^[31]

Airtightness minimizes the amount of warm — or cool — air that can pass through the structure, enabling the mechanical ventilation system to recover the heat before discharging the air externally.^[2]

Ventilation

Use of passive natural ventilation is an integral component of passive house design where ambient temperature is conducive — either by singular or cross ventilation; by a simple opening or enhanced by the stack effect from smaller ingress with larger egress windows and/or clerestory-operable skylight.

When ambient climate is not conducive, mechanical heat recovery ventilation systems, with a heat recovery rate of over 80% and high-efficiency electronically commutated motors (ECM), are employed to maintain air quality, and to recover sufficient heat to dispense with a conventional central heating system.^[2] Since passively designed buildings are essentially air-tight, the rate of air change can be optimized and carefully controlled at about 0.4 air changes per hour. All ventilation ducts are insulated and sealed against leakage.

Some Passivhaus builders promote the use of earth warming tubes (typically ≈200 mm (~7,9 in) diameter, ≈40 m (~130 ft) long at a depth of ≈1.5 m (~5 ft)). These are buried in the soil to act as earth-to-air heat exchangers and pre-heat (or pre-cool) the intake air for the ventilation system. In cold weather the warmed air also prevents ice formation in the heat recovery system's heat exchanger. Concerns about this technique have arisen in some climates due to problems with condensation and mold.^[32]

Alternatively, an earth to air heat exchanger can use a liquid circuit instead of an air circuit, with a heat exchanger (battery) on the supply air.

Space heating

Passivhaus: In addition to the heat exchanger (centre), a micro-heat pump extracts heat from the exhaust air (left) and hot water heats the ventilation air (right). The ability to control building temperature using only the normal volume of ventilation air is fundamental.

In addition to using passive solar gain, Passivhaus buildings make extensive use of their intrinsic heat from internal sources—such as waste heat from lighting, white goods (major appliances) and other electrical devices (but not dedicated heaters)—as well as body heat from the people and other animals inside the building. This is due to the fact that people, on average, emit heat equivalent to 100 watts each of radiated thermal energy.

Together with the comprehensive energy conservation measures taken, this means that a conventional central heatingsystem is not necessary, although they are sometimes installed due to client skepticism.^[33]

Instead, Passive houses sometimes have a dual purpose 800 to 1,500 watt heating and/or cooling element integrated with the supply air duct of the ventilation system, for use during the coldest days. It is fundamental to the design that all the heat required can be transported by the normal low air volume required for ventilation. A maximum air temperature of 50 °C (122 °F) is applied, to prevent any possible smell of scorching from dust that escapes the filters in the system.

The air-heating element can be heated by a small heat pump, by direct solar thermal energy, annualized geothermal solar, or simply by a natural gas or oil burner. In some cases a micro-heat pump is used to extract additional heat from the exhaust ventilation air, using it to heat either the incoming air or the hot water storage tank. Small wood-burning stoves can also be used to heat the water tank, although care is required to ensure that the room in which stove is located does not overheat.

Beyond the recovery of heat by the heat recovery ventilation unit, a well designed Passive house in the European climate should not need any supplemental heat source if the heating load is kept under 10W/m².^[34]

Because the heating capacity and the heating energy required by a passive house both are very low, the particular energy source selected has fewer financial implications than in a traditional building, although renewable energy sources are well suited to such low loads.

Lighting and electrical appliances

See also: Daylighting, Passive daylighting, Active daylighting, and Ecological footprint

To minimize the total primary energy consumption, the many passive and active daylighting techniques are the first daytime solution to employ. For low light level days, non-daylighted spaces, and nighttime; the use of creative-sustainable lighting design using low-energy sources such as 'standard voltage' compact fluorescent lamps and solid-state lighting with Light-emitting diode-LED lamps, organic light-emitting diodes, and PLED - polymer light-emitting diodes; and 'low voltage' electrical filament-Incandescent light bulbs, and compact Metal halide, Xenon and Halogen lamps, can be used.

Solar powered exterior circulation, security, and landscape lighting - with photovoltaic cells on each fixture or connecting to a central Solar panel system, are available forgardens and outdoor needs. Low voltage systems can be used for more controlled or independent illumination, while still using less electricity than conventional fixtures and lamps. Timers, motion detection and natural light operation sensors reduce energy consumption, and light pollution even further for a Passivhaus setting.

Appliance consumer products meeting independent energy efficiency testing and receiving Ecolabel certification marks for reduced electrical-'natural-gas' consumption and product manufacturing carbon emission labels are preferred for use in Passive houses. The ecolabel certification marks of Energy Star and EKOenergy are examples.

Traits of passive houses

Typically, passive houses feature:

• Fresh, clean air: Note that for the parameters tested, and provided the filters (minimum F6) are maintained, HEPA quality air is provided. 0.3 air changes per hour (ACH) are recommended, otherwise the air can become "stale" (excess CO₂, flushing of indoor air pollutants) and any greater, excessively dry (less than 40% humidity). This implies careful selection of interior finishes and furnishings, to minimize indoor air pollution from VOC's (e.g., formaldehyde). This can be counteracted somewhat by opening a window for a very brief time, by plants, and by indoor fountains.
• Because of the high resistance to heat flow (high R-value insulation), there are no "outside walls" which are colder than other walls.
• Homogeneous interior temperature: it is impossible to have single rooms (e.g. the sleeping rooms) at a different temperature from the rest of the house. Note that the relatively high temperature of the sleeping areas is physiologically not considered desirable by some building scientists. Bedroom windows can be cracked open slightly to alleviate this when necessary.
• Slow temperature changes: with ventilation and heating systems switched off, a passive house typically loses less than 0.5 °C (1 °F) per day (in winter), stabilizing at around 15 °C (59 °F) in the central European climate.
• Quick return to normal temperature: opening windows or doors for a short time has only a limited effect; after aperatures are closed, the air very quickly returns to the "normal" temperature.

, others, such as superinsulation, already existed, and the concept of passive solar building design dates back to antiquity.

[edit]Standards

The Passivhaus standard for central Europe requires that the building fulfills the following requirements:[22][23]

The building must be designed to have an annual heating demand as calculated with the Passivhaus Planning Package of not more than 15 kWh/m² per year (4746 btu/ft² per year) in heating and 15 kWh/m² per year cooling energy OR to be designed with a peak heat load of 10W/m²

Total primary energy (source energy for electricity and etc.) consumption (primary energy for heating, hot water and electricity) must not be more than 120 kWh/m² per year (3.79 × 104 btu/ft² per year)

The building must not leak more air than 0.6 times the house volume per hour (n50 ≤ 0.6 / hour) at 50 Pa (N/m²) as tested by a blower door

Recommendations

Further, the specific heat load for the heating source at design temperature is recommended, but not required, to be less than 10 W/m² (3.17 btu/h.ft² per hour).

These standards are much higher than houses built to most normal building codes. For comparisons, see the international comparisons section below.

National partners within the 'consortium for the Promotion of European Passive Houses' are thought to have some flexibility to adapt these limits locally.[24]

Space heating requirement

By achieving the Passivhaus standards, qualified buildings are able to dispense with conventional heating systems. While this is an underlying objective of the Passivhaus standard, some type of heating will still be required and most Passivhaus buildings do include a system to provide supplemental space heating. This is normally distributed through the low-volume heat recovery ventilation system that is required to maintain air quality, rather than by a conventional hydronic or high-volume forced-air heating system, as described in the space heating section below.

Construction costs

In Passivhaus buildings, the cost savings from dispensing with the conventional heating system can be used to fund the upgrade of the building envelope and the heat recovery ventilation system. With careful design and increasing competition in the supply of the specifically designed Passivhaus building products, in Germany it is now possible to construct buildings for the same cost as those built to normal German building standards, as was done with the Passivhaus apartments at Vauban, Freiburg.[25] On average, however, passive houses are still up to 14% more expensive upfront than conventional buildings.[26]

Evaluations have indicated that while it is technically possible, the costs of meeting the Passivhaus standard increase significantly when building in Northern Europe above 60° latitude.[27][28] European cities at approximately 60° include Helsinki in Finland and Bergen in Norway. London is at 51°; Moscow is at 55°.

These facts have led a number of architects to construct buildings that use the ground under the building for massive heat storage to shift heat production from the winter to the summer. Some buildings can also shift cooling from the summer to the winter. At least one designer uses a passive thermosiphon carrying only air, so the process can be accomplished without expensive, unreliable machinery.[29] (See also Annualized geo solar)

Design and construction

The Passivhaus uses a combination of low-energy building techniques and technologies.

Achieving the major decrease in heating energy consumption required by the standard involves a shift in approach to building design and construction. Design may be assisted by use of the 'Passivhaus Planning Package' (PHPP),[30] which uses specifically designed computer simulations.

To achieve the standards, a number of techniques and technologies are used in combination:[2]

Passive solar design and landscape

Passive solar building design and energy-efficient landscaping support the Passive house energy conservation and can integrate them into a neighborhood and environment. Following passive solar building techniques, where possible buildings are compact in shape to reduce their surface area, with principal windows oriented towards the equator - south in the northern hemisphere and north in the southern hemisphere - to maximize passive solar gain. However, the use of solar gain, especially in temperate climate regions, is secondary to minimizing the overall house energy requirements. In climates and regions needing to reduce excessive summer passive solar heat gain, whether from direct or reflected sources, trees, attached pergolas with vines, vertical gardens, green roofs, and other techniques are implemented.

Passive houses can be constructed from dense or lightweight materials, but some internal thermal mass is normally incorporated to reduce summer peak temperatures, maintain stable winter temperatures, and prevent possible overheating in spring or autumn before the higher sun angle "shades" mid-day wall exposure and window penetration. Exterior wall color, when the surface allows choice, for reflection or absorption insolation qualities depends on the predominant year-round ambient outdoor temperature. The use of deciduous trees and wall trellised or self attaching vines can assist in climates not at the temperature extremes.

Superinsulation

Passivhaus buildings employ superinsulation to significantly reduce the heat transfer through the walls, roof and floor compared to conventional buildings.[31] A wide range of thermal insulation materials can be used to provide the required high R-values (low U-values, typically in the 0.10 to 0.15 W/(m².K) range). Special attention is given to eliminating thermal bridges.

A disadvantage resulting from the thickness of wall insulation required is that, unless the external dimensions of the building can be enlarged to compensate, the internal floor area of the building may be less compared to traditional construction.

In Sweden, to achieve passive house standards, the insulation thickness would be 335 mm (about 13 in) (0.10 W/(m².K)) and the roof 500 mm (about 20 in) (U-value 0.066 W/(m².K)).

Advanced window technology

Typical Passive House windows

To meet the requirements of the Passivhaus standard, windows are manufactured with exceptionally high R-values (low U-values, typically 0.85 to 0.70 W/(m².K) for the entire window including the frame). These normally combine triple-pane insulated glazing (with a good solar heat-gain coefficient,[2][31] low-emissivity coatings, sealed argon or krypton gas filled inter-pane voids, and 'warm edge' insulating glass spacers) with air-seals and specially developed thermally broken window frames.

In Central Europe and most of the United States, for unobstructed south-facing Passivhaus windows, the heat gains from the sun are, on average, greater than the heat losses, even in mid-winter.

Airtightness

Building envelopes under the Passivhaus standard are required to be extremely airtight compared to conventional construction. This is achieved through air barriers, careful sealing of every construction joint in the building envelope, and sealing of all service penetrations.[31]

Airtightness minimizes the amount of warm — or cool — air that can pass through the structure, enabling the mechanical ventilation system to recover the heat before discharging the air externally.[2]

[edit]Ventilation

Use of passive natural ventilation is an integral component of passive house design where ambient temperature is conducive — either by singular or cross ventilation; by a simple opening or enhanced by the stack effect from smaller ingress with larger egress windows and/or clerestory-operable skylight.

When ambient climate is not conducive, mechanical heat recovery ventilation systems, with a heat recovery rate of over 80% and high-efficiency electronically commutated motors (ECM), are employed to maintain air quality, and to recover sufficient heat to dispense with a conventional central heating system.[2] Since passively designed buildings are essentially air-tight, the rate of air change can be optimized and carefully controlled at about 0.4 air changes per hour. All ventilation ducts are insulated and sealed against leakage.

Some Passivhaus builders promote the use of earth warming tubes (typically ≈200 mm (~7,9 in) diameter, ≈40 m (~130 ft) long at a depth of ≈1.5 m (~5 ft)). These are buried in the soil to act as earth-to-air heat exchangers and pre-heat (or pre-cool) the intake air for the ventilation system. In cold weather the warmed air also prevents ice formation in the heat recovery system's heat exchanger. Concerns about this technique have arisen in some climates due to problems with condensation and mold.[32]

Alternatively, an earth to air heat exchanger can use a liquid circuit instead of an air circuit, with a heat exchanger (battery) on the supply air.

Space heating

Passivhaus: In addition to the heat exchanger (centre), a micro-heat pump extracts heat from the exhaust air (left) and hot water heats the ventilation air (right). The ability to control building temperature using only the normal volume of ventilation air is fundamental.

In addition to using passive solar gain, Passivhaus buildings make extensive use of their intrinsic heat from internal sources—such as waste heat from lighting, white goods (major appliances) and other electrical devices (but not dedicated heaters)—as well as body heat from the people and other animals inside the building. This is due to the fact that people, on average, emit heat equivalent to 100 watts each of radiated thermal energy.

Together with the comprehensive energy conservation measures taken, this means that a conventional central heating system is not necessary, although they are sometimes installed due to client skepticism.[33]

Instead, Passive houses sometimes have a dual purpose 800 to 1,500 watt heating and/or cooling element integrated with the supply air duct of the ventilation system, for use during the coldest days. It is fundamental to the design that all the heat required can be transported by the normal low air volume required for ventilation. A maximum air temperature of 50 °C (122 °F) is applied, to prevent any possible smell of scorching from dust that escapes the filters in the system.

The air-heating element can be heated by a small heat pump, by direct solar thermal energy, annualized geothermal solar, or simply by a natural gas or oil burner. In some cases a micro-heat pump is used to extract additional heat from the exhaust ventilation air, using it to heat either the incoming air or the hot water storage tank. Small wood-burning stoves can also be used to heat the water tank, although care is required to ensure that the room in which stove is located does not overheat.

Beyond the recovery of heat by the heat recovery ventilation unit, a well designed Passive house in the European climate should not need any supplemental heat source if the heating load is kept under 10W/m².[34]

Because the heating capacity and the heating energy required by a passive house both are very low, the particular energy source selected has fewer financial implications than in a traditional building, although renewable energy sources are well suited to such low loads.

[edit]Lighting and electrical appliances

See also: Daylighting, Passive daylighting, Active daylighting, and Ecological footprint

To minimize the total primary energy consumption, the many passive and active daylighting techniques are the first daytime solution to employ. For low light level days, non-daylighted spaces, and nighttime; the use of creative-sustainable lighting design using low-energy sources such as 'standard voltage' compact fluorescent lamps and solid-state lighting with Light-emitting diode-LED lamps, organic light-emitting diodes, and PLED - polymer light-emitting diodes; and 'low voltage' electrical filament-Incandescent light bulbs, and compact Metal halide, Xenon and Halogen lamps, can be used.

Solar powered exterior circulation, security, and landscape lighting - with photovoltaic cells on each fixture or connecting to a central Solar panel system, are available for gardens and outdoor needs. Low voltage systems can be used for more controlled or independent illumination, while still using less electricity than conventional fixtures and lamps. Timers, motion detection and natural light operation sensors reduce energy consumption, and light pollution even further for a Passivhaus setting.

Appliance consumer products meeting independent energy efficiency testing and receiving Ecolabel certification marks for reduced electrical-'natural-gas' consumption and product manufacturing carbon emission labels are preferred for use in Passive houses. The ecolabel certification marks of Energy Star and EKOenergy are examples.

Traits of passive houses

Typically, passive houses feature:

Fresh, clean air: Note that for the parameters tested, and provided the filters (minimum F6) are maintained, HEPA quality air is provided. 0.3 air changes per hour (ACH) are recommended, otherwise the air can become "stale" (excess CO2, flushing of indoor air pollutants) and any greater, excessively dry (less than 40% humidity). This implies careful selection of interior finishes and furnishings, to minimize indoor air pollution from VOC's (e.g., formaldehyde). This can be counteracted somewhat by opening a window for a very brief time, by plants, and by indoor fountains.

Because of the high resistance to heat flow (high R-value insulation), there are no "outside walls" which are colder than other walls.

Homogeneous interior temperature: it is impossible to have single rooms (e.g. the sleeping rooms) at a different temperature from the rest of the house. Note that the relatively high temperature of the sleeping areas is physiologically not considered desirable by some building scientists. Bedroom windows can be cracked open slightly to alleviate this when necessary.

Slow temperature changes: with ventilation and heating systems switched off, a passive house typically loses less than 0.5 °C (1 °F) per day (in winter), stabilizing at around 15 °C (59 °F) in the central European climate.

Quick return to normal temperature: opening windows or doors for a short time has only a limited effect; after aperatures are closed, the air very quickly returns to the "normal" temperature.

Standards

The Passivhaus standard for central Europe requires that the building fulfills the following requirements:^[22][23]

·        The building must be designed to have an annual heating demand as calculated with the Passivhaus Planning Package of not more than 15 kWh/m² per year (4746 btu/ft² per year) in heating and 15 kWh/m² per year cooling energy OR to be designed with a peak heat load of 10W/m²

·        Total primary energy (source energy for electricity and etc.) consumption (primary energy for heating, hot water andelectricity) must not be more than 120 kWh/m² per year (3.79 × 10⁴ btu/ft² per year)

·        The building must not leak more air than 0.6 times the house volume per hour (n₅₀ ≤ 0.6 / hour) at 50 Pa (N/m²) as tested by a blower door

Recommendations

·        Further, the specific heat load for the heating source at design temperature is recommended, but not required, to be less than 10 W/m² (3.17 btu/h.ft² per hour).

These standards are much higher than houses built to most normal building codes. For comparisons, see the international comparisons section below.

National partners within the 'consortium for the Promotion of European Passive Houses' are thought to have some flexibility to adapt these limits locally

Space heating requirement

By achieving the Passivhaus standards, qualified buildings are able to dispense with conventional heating systems. While this is an underlying objective of the Passivhaus standard, some type of heating will still be required and most Passivhaus buildings do include a system to provide supplemental space heating. This is normally distributed through the low-volume heat recovery ventilation system that is required to maintain air quality, rather than by a conventional hydronic or high-volume forced-air heating system, as described in the space heating section below.

Construction costs

In Passivhaus buildings, the cost savings from dispensing with the conventional heating system can be used to fund the upgrade of the building envelope and the heat recovery ventilation system. With careful design and increasing competition in the supply of the specifically designed Passivhaus building products, in Germany it is now possible to construct buildings for the same cost as those built to normal German building standards, as was done with the Passivhaus apartments at Vauban, Freiburg.^[25]On average, however, passive houses are still up to 14% more expensive upfront than conventional buildings.^[26]

Evaluations have indicated that while it is technically possible, the costs of meeting the Passivhaus standard increase significantly when building in Northern Europe above 60° latitude.^[27][28] European cities at approximately 60° include Helsinki in Finland and Bergen in Norway. London is at 51°; Moscow is at 55°.

These facts have led a number of architects to construct buildings that use the ground under the building for massive heat storage to shift heat production from the winter to the summer. Some buildings can also shift cooling from the summer to the winter. At least one designer uses a passive thermosiphon carrying only air, so the process can be accomplished without expensive, unreliable machinery.^[29] (See also Annualized geo solar

Design and construction

The Passivhaus uses a combination oflow-energy building techniques and technologies.

Achieving the major decrease in heating energy consumption required by the standard involves a shift in approach to building design and construction. Design may be assisted by use of the 'Passivhaus Planning Package' (PHPP),^[30] which uses specifically designed computer simulations.

To achieve the standards, a number of techniques and technologies are used in combination

^[Passive solar design and landscape

Passive solar building design and energy-efficient landscaping support the Passive house energy conservation and can integrate them into a neighborhood and environment. Following passive solar building techniques, where possible buildings are compact in shape to reduce their surface area, with principal windows oriented towards the equator - south in the northern hemisphere and north in the southern hemisphere - to maximize passive solar gain. However, the use of solar gain, especially in temperate climate regions, is secondary to minimizing the overall house energy requirements. In climates and regions needing to reduce excessive summer passive solar heat gain, whether from direct or reflected sources, Brise soleil, trees, attached pergolas with vines, vertical gardens, green roofs, and other techniques are implemented.

Passive houses can be constructed from dense or lightweight materials, but some internal thermal mass is normally incorporated to reduce summer peak temperatures, maintain stable winter temperatures, and prevent possible overheating in spring or autumn before the higher sun angle "shades" mid-day wall exposure and window penetration. Exterior wall color, when the surface allows choice, for reflection or absorption insolation qualities depends on the predominant year-round ambient outdoor temperature. The use of deciduous trees and wall trellised or self attaching vines can assist in climates not at the temperature extremes.

Superinsulation

Passivhaus buildings employ superinsulation to significantly reduce the heat transfer through the walls, roof and floor compared to conventional buildings.^[31] A wide range ofthermal insulation materials can be used to provide the required high R-values (low U-values, typically in the 0.10 to 0.15 W/(m².K) range). Special attention is given to eliminating thermal bridges.

A disadvantage resulting from the thickness of wall insulation required is that, unless the external dimensions of the building can be enlarged to compensate, the internal floor area of the building may be less compared to traditional construction.

In Sweden, to achieve passive house standards, the insulation thickness would be 335 mm (about 13 in) (0.10 W/(m².K)) and the roof 500 mm (about 20 in) (U-value 0.066 W/(m².K)).

Advanced window technology

Typical Passive House windows

To meet the requirements of the Passivhaus standard, windows are manufactured with exceptionally high R-values (low U-values, typically 0.85 to 0.70 W/(m².K) for the entire window including the frame). These normally combine triple-paneinsulated glazing (with a good solar heat-gain coefficient,^[2][31] low-emissivity coatings, sealed argon or krypton gas filled inter-pane voids, and 'warm edge' insulating glass spacers) with air-seals and specially developed thermally broken window frames.

In Central Europe and most of the United States, for unobstructed south-facing Passivhaus windows, the heat gains from the sun are, on average, greater than the heat losses, even in mid-winter.

Airtightness

Building envelopes under the Passivhaus standard are required to be extremely airtight compared to conventional construction. This is achieved through air barriers, careful sealing of every construction joint in the building envelope, and sealing of all service penetrations.^[31]

Airtightness minimizes the amount of warm — or cool — air that can pass through the structure, enabling the mechanical ventilation system to recover the heat before discharging the air externally.^[

Ventilation

Use of passive natural ventilation is an integral component of passive house design where ambient temperature is conducive — either by singular or cross ventilation; by a simple opening or enhanced by the stack effect from smaller ingress with larger egress windows and/or clerestory-operable skylight.

When ambient climate is not conducive, mechanical heat recovery ventilation systems, with a heat recovery rate of over 80% and high-efficiency electronically commutated motors (ECM), are employed to maintain air quality, and to recover sufficient heat to dispense with a conventional central heating system.^[2] Since passively designed buildings are essentially air-tight, the rate of air change can be optimized and carefully controlled at about 0.4 air changes per hour. All ventilation ducts are insulated and sealed against leakage.

Some Passivhaus builders promote the use of earth warming tubes (typically ≈200 mm (~7,9 in) diameter, ≈40 m (~130 ft) long at a depth of ≈1.5 m (~5 ft)). These are buried in the soil to act as earth-to-air heat exchangers and pre-heat (or pre-cool) the intake air for the ventilation system. In cold weather the warmed air also prevents ice formation in the heat recovery system's heat exchanger. Concerns about this technique have arisen in some climates due to problems with condensation and mold.^[32]

Alternatively, an earth to air heat exchanger can use a liquid circuit instead of an air circuit, with a heat exchanger (battery) on the supply air.

Space heating

Passivhaus: In addition to the heat exchanger (centre), a micro-heat pump extracts heat from the exhaust air (left) and hot water heats the ventilation air (right). The ability to control building temperature using only the normal volume of ventilation air is fundamental.

In addition to using passive solar gain, Passivhaus buildings make extensive use of their intrinsic heat from internal sources—such as waste heat from lighting, white goods (major appliances) and other electrical devices (but not dedicated heaters)—as well as body heat from the people and other animals inside the building. This is due to the fact that people, on average, emit heat equivalent to 100 watts each of radiated thermal energy.

Together with the comprehensive energy conservation measures taken, this means that a conventional central heatingsystem is not necessary, although they are sometimes installed due to client skepticism.^[33]

Instead, Passive houses sometimes have a dual purpose 800 to 1,500 watt heating and/or cooling element integrated with the supply air duct of the ventilation system, for use during the coldest days. It is fundamental to the design that all the heat required can be transported by the normal low air volume required for ventilation. A maximum air temperature of 50 °C (122 °F) is applied, to prevent any possible smell of scorching from dust that escapes the filters in the system.

The air-heating element can be heated by a small heat pump, by direct solar thermal energy, annualized geothermal solar, or simply by a natural gas or oil burner. In some cases a micro-heat pump is used to extract additional heat from the exhaust ventilation air, using it to heat either the incoming air or the hot water storage tank. Small wood-burning stoves can also be used to heat the water tank, although care is required to ensure that the room in which stove is located does not overheat.

Beyond the recovery of heat by the heat recovery ventilation unit, a well designed Passive house in the European climate should not need any supplemental heat source if the heating load is kept under 10W/m².^[34]

Because the heating capacity and the heating energy required by a passive house both are very low, the particular energy source selected has fewer financial implications than in a traditional building, although renewable energy sources are well suited to such low loads.

Lighting and electrical appliances

See also: Daylighting, Passive daylighting, Active daylighting, and Ecological footprint

To minimize the total primary energy consumption, the many passive and active daylighting techniques are the first daytime solution to employ. For low light level days, non-daylighted spaces, and nighttime; the use of creative-sustainable lighting design using low-energy sources such as 'standard voltage' compact fluorescent lamps and solid-state lighting with Light-emitting diode-LED lamps, organic light-emitting diodes, and PLED - polymer light-emitting diodes; and 'low voltage' electrical filament-Incandescent light bulbs, and compact Metal halide, Xenon and Halogen lamps, can be used.

Solar powered exterior circulation, security, and landscape lighting - with photovoltaic cells on each fixture or connecting to a central Solar panel system, are available forgardens and outdoor needs. Low voltage systems can be used for more controlled or independent illumination, while still using less electricity than conventional fixtures and lamps. Timers, motion detection and natural light operation sensors reduce energy consumption, and light pollution even further for a Passivhaus setting.

Appliance consumer products meeting independent energy efficiency testing and receiving Ecolabel certification marks for reduced electrical-'natural-gas' consumption and product manufacturing carbon emission labels are preferred for use in Passive houses. The ecolabel certification marks of Energy Star and EKOenergy are examples.

Traits of passive houses

Typically, passive houses feature:

·        Fresh, clean air: Note that for the parameters tested, and provided the filters (minimum F6) are maintained, HEPA quality air is provided. 0.3 air changes per hour (ACH) are recommended, otherwise the air can become "stale" (excess CO₂, flushing of indoor air pollutants) and any greater, excessively dry (less than 40% humidity). This implies careful selection of interior finishes and furnishings, to minimize indoor air pollution from VOC's (e.g., formaldehyde). This can be counteracted somewhat by opening a window for a very brief time, by plants, and by indoor fountains.

·        Because of the high resistance to heat flow (high R-value insulation), there are no "outside walls" which are colder than other walls.

·        Homogeneous interior temperature: it is impossible to have single rooms (e.g. the sleeping rooms) at a different temperature from the rest of the house. Note that the relatively high temperature of the sleeping areas is physiologically not considered desirable by some building scientists. Bedroom windows can be cracked open slightly to alleviate this when necessary.

·        Slow temperature changes: with ventilation and heating systems switched off, a passive house typically loses less than 0.5 °C (1 °F) per day (in winter), stabilizing at around 15 °C (59 °F) in the central European climate.

·        Quick return to normal temperature: opening windows or doors for a short time has only a limited effect; after aperatures are closed, the air very quickly returns to the "normal" temperature.