Passive House - Soup du jour?

I have been asked how you build a Passive house – for me that’s like asking “What’s the recipe for soup?”  I know the person wants to know what are the materials, how thick are the walls, what size windows are used, but my answer is always the same – it depends.  Passive House is not a set of plans or a recipe, it is a design goal.  If you can find a way to use a material or design and still meet the requirements, then you can have a Passive House.  Want to build with Straw?  Cob? Rammed Earth? What if you want to build with wood, or steel, or some kind of new composite?  If your designer can make the numbers work on the PHPP and the builder can pass the blower door test, you can have a Passive House.  But you don’t have to go to some unusual method, unless that particularly interests you.  If you want to build a house that is built like…. a house with studs and insulation on a concrete foundation and a roof with trusses… you know, a house… you can do it.  There are even those who have gone before who have created a set of “recipes” as it were of what worked for them.

Passivhaus Bauteikatalog – Details for Passive Houses is a wonderful collection of constructions that have been proven on Passive House projects in Europe.  The book is written in both German and English and shows details of materials, and methods that have worked successfully.  What it doesn’t show is how to recreate those same constructions here with the materials and their insulative properties that we have available to us.  That’s where being a good cook comes in.  You know a yam is a good substitute for a potato or zuchinni is the same as crookneck squash in a recipe.  The same thing can work with construction details.  Sure you could have something shipped over here from Germany, or you can find an equivalent – you just need to figure out if that equivalent is different enough that it changes the mix.  The yam is sweeter than the potato, the crookneck and zuchinni are almost identical.

Eventually we will have a version of the Passivhaus Bauteikatalog with details that use materials found in the US.  Until then we can start with the things that have worked in Europe and adapt them not only to our materials, but also our climates.  How do we do that?  We model the construction in the PHPP, THERM, WUFI and any other program that will allow us to know what the building will be expected to operate like once it is complete.  Passive House is about planning, not guessing.  If you want to use bales of used carpeting as insulation, you better figure out a way to model it correctly to meet Passive House standards or it will never pass certification.  But really, if you want to use an odd combination of materials, do ask yourself if it will ultimately benefit the construction.  Take it from someone who once tried putting cinnamon in turkey soup – not everything is a good idea!

If you would like to preview part of the book online, it is available in German, but Google translate allows you to see it in English (click on “Components”).  The book itself is available through Amazon.com and is quite an excellent reference.