Passive House in 90 Seconds" by Hans Jorn-Eich at Pinwheel Structures www.pinwheelstructures.com
PASSIVE HOUSE (Passivhaus)
Written by Bryn Davidson, B.Eng. M.Arch. LEED-AP, Co-owner of Lanefab Design/Build www.lanefab.com
'Passive House' is an international standard for energy efficient buildings where a house (or any other type of building) is so well insulated and air tight that it can function without a primary heating system. Passive house projects deliver the highest level of comfort, and the most cost effective bundle of energy saving strategies.
Like LEED, BuiltGreen (or other rating systems) there are Passive House organizations, such as PHI, CanPHI, or PHIUS, which can certify buildings - though many projects are built to the standard without going through certification.
In contrast with these other rating systems, the PH rating focuses primarily on comfort and energy consumption (vs. LEED which looks at a wider range of green building issues) but PH goes well beyond LEED in this area - usually resulting in projects that use 90% less energy for space heating than a typical building.
The typical passive house will have very thick walls and roofs, a fairly simple shape, and high performance windows and doors. Typical walls might be 12" to 24" thick (R35 to R60) and roofs might be 18" to 36" thick (R50 to R100). Windows are triple glazed or better, and doors usually have several levels of weatherstripping.
One of the key criteria for achieving the passive house standard is having an airtightness rating less than 0.6 ACH (air changes per hour... i.e. 0.6x the volume of the house). The airtightness is assessed using a blower door apparatus.
The energy efficiency targets were very specifically formulated such that the building sits in the 'sweet spot' which balances construction costs vs. performance. By hitting the energy targets a Passive House can eliminate most of the cost of a conventional heating system (thereby offsetting much of the cost of upgrading insulation and windows).
How is a Passive House different?
Very thick walls and roofs (our typical PH wall is 17" thick)
Very quiet and comfortable, without cold spots or condensation.
Usually a simpler shape (to reduce heat lost through bump outs, dormers etc.)
Very high quality triple-glazed windows and doors
A high efficiency ventilation system with heat recovery (HRV) that brings fresh air to every room year-round.
Many passive houses have recirculating kitchen hoods with charcoal filters that remove smoke, grease and smells.
Many passive houses also use energy efficient 'vent-less' dryers that use a heat pump to extract moisture.
Passive houses can be built with any type of hot water system.
A passive house can work really well with solar panels, but solar panels are not required to meet the PH standard