‘Passive House’ is a design standard that uses insulation, airtightness, window and door design, ventilation systems with heat recovery, and elimination of thermal bridges to achieve thermal comfort with minimal heating and cooling.
Originally developed in Germany in the 1990s, Passive House principles are now being used worldwide.
To meet the Passive House standard, a building must meet certain requirements.
Airtightness
The airtightness requirements for Passive Houses in Perth, Western Australia, are that the building envelope must achieve an airtightness of less than 0.6 ACH50 (air changes per hour at 50 Pascals pressure difference). This is achieved by using a combination of sealing air leaks and installing an airtight barrier around windows and doors. Sealed the building from outside air and prevents energy loss through drafts or infiltration.
Insulation
The building must have a high level of insulation, to reduce heat loss and maintain a comfortable indoor temperature. The walls, floors, and ceilings must be insulated with materials that have a high R-value.
Windows and Doors
The windows and doors must be highly insulated, with U-values of 0.8 or lower, highly efficient and high solar gain. This ensures that the building is well insulated from the outside environment while allowing natural light to enter.
Windows and doors must be carefully sized and placed to control the amount of solar heat gain in winter while reducing unwanted heat gain in summer.
Advanced window technology should be used, such as triple or quadruple-pane insulated glazing, low-emissivity coatings, sealed argon or krypton gas filled inter-pane voids, and ‘warm edge’ insulating glass spacers with frames that reduce heat transfer from inside to outside.
Appropriate windows are often ‘tilt and turn’ and large doors use a ‘lift and slide’ mechanism to ensure they are airtight when closed.
Ventilation
The building must have a mechanical ventilation system with heat recovery to ensure fresh air is circulated throughout the building while maintaining energy efficiency.
Thermal Bridges
Thermal bridging is the process by which heat is conducted through structural elements such as walls, roofs and floors. To prevent thermal bridging in Passive Houses in Perth, Western Australia, insulation must be installed around all structural elements to reduce heat transfer and areas where heat can escape from the building.
Certification
By meeting these requirements, a building can achieve the Passive House standard and enjoy significant energy savings and improved comfort levels.
The Passive House Institute administers a certification scheme that allows a building to be called a Certified Passive House once it has met certain performance standards.
In addition to the requirements outlined above, a Certified Passive House must also meet certain energy performance standards.
The building must have an annual heating demand of no more than 15 kWh/m2 per year and an annual cooling demand of no more than 15 kWh/m2 per year. It must also have a primary energy demand of no more than 120 kWh/m2 per year.
These energy performance standards are designed to ensure that the building is as energy efficient as possible.
Passive house is a voluntary standard for energy efficiency in buildings, resulting in ultra-low energy buildings.
In order to achieve the Passive House standard, a building must be designed and constructed with careful attention to detail.