Passive House explained in 90 Seconds
To touch on a few of the items in a little more detail:
1) Proper Insulation: In our climate (Climate Zone 5) a good starting point for insulation levels are:
- R-30 Sub Slab Insulation
- R-40 Exterior and Foundation Walls
- R-7 Windows (Come on America - Time to make a Good Window!)
- R-90 Attic Insulation
2) No Air Leaks: These thermal images taken during a blower door test show how air is constantly leaking out of your home:
Air leaks visible around a recessed light Air leaks visible around an exterior light switch
Proper construction sequencing, design and multiple blower door tests done during construction will ensure an airtight building. The airtight layer MUST be designed into a passive house. Draw a red line around any cross section of your house without picking up your pen. It is tougher than it sounds!
Blue lines are ceiling joists directly connected to the outside Minimal heat loss though framing
4) Proper Windows: Right now there is not an American Company making windows as efficient as the ones in Europe.
The upper window is an Energy Star rated American window, the bottom window is a Passive house window. I will get into more details on the anatomy of a window later on. Bottom line: A properly oriented Passive House window will let in more energy than it will let out over the course of a year.
5) Proper Orientation: South facing glass with proper shading will do a majority of the heating and lighting in a passive house. See this google sketch-up rendering of shading over the course of the year:
6) Proper Mechanical Ventilation: With an air tight building fresh air is needed to keep the occupants healthy. An HRV constantly brings in the fresh air (filters it) and delivers it to the living spaces while removing the stale air from the kitchens and bathrooms. It captures the heat from the outgoing air and transfers it to the incoming air - in some cases as much as 90% of the heat is recovered!
For more information see the following links: