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.
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.
