Would a passive house approach work for what I am trying to do with the permaculture house concept?
The envelope (the exterior walls) of this permaculture house has been a puzzle for me for awhile. I’ve spent a considerable amount of time on the plan and flow and I am bound to spend some unimaginable early morning hours sketching and designing my exterior walls. I have to say the Passive House has shown up more than a few times.
Passive house design begun its roots in North America, Canada and Germany-mainly as a response to the cold climate. There are ways to use this for the hot Texas climate, but the technologies are not as developed as they are for the colder temps. The Passive House Institute US (PHIUS) is headquartered in Chicago – also a cold climate area. I’ve seen some PH builds in Texas where the designers themselves, in coordination with the PHIUS, had to come up with their own solutions since the development for hot humid climate is still catching up.
There are 2 main components to the Passive House approach: the building envelope and the mechanical system.
Passive house design in a nutshell focuses on super insulating the entire home. There is very little cost in heating and cooling the home because of this. Most of your expense is at the front end, paying for the cost of the insulation and the details to keep leaks minimal. You get a ROI as a reduction in your utility bill through the life of the building. According to permaculture principles, this energy audit works in that you put your systems in at the beginning-it is an investment-but that expense in the system pays you back in perpetuity (theoretically).
You also have a high efficiency mechanical system which should include filtration and fresh air intake. With the building hermetically sealed, the fresh air intake comes in as part of the mechanical system. It goes straight to a heat exchanger so this does not leak uncontrolled temperature into the home. Circulated air also gets exhausted back outside.
HOW THIS TRANSLATES TO A CONVENTIONAL HOME:
According to PHIUS, an example of a PH standard when applied to Texas would have the following insulation values:
Wall = R31 to R51
Ceiling = R49 to R80
Slab = 2 to 4 ft R8-20 vertical perimeter
Passive home buildings typically cost 5-10% more than a conventional home. This estimate is from the institution that is promoting it, so take that with a grain of salt. One must be careful with these, considering how statistics can be interpreted in different ways or if incentives were used to achieve that results. Nothing against that statistic, just a note that one needs to take these with a grain of salt. Assuming this is accurate and going back to how this is earned back in perpetuity from your utility savings I think this is worth it.
MY TAKE ON IT:
I am still learning about this technology – granted it is not new, but it is also not something I’ve used. I am not new to the green building scene – in fact I am grandfathered into the early LEED program and no longer need continuing education credits. One of my main hold outs with it is that for it to work, the indoor air needs to be sealed off from the outside air. I personally prefer having fresh air, a nice breeze blowing thru the home and reminding me that I am connected to the rest of my homestead. I feel that now on my tiny property-how much more when I have a larger established food forest.
As Bill Mollison once said, architects are one of the most dangerous experimenters in the built environment (or something along those lines). Designers do tend to force our control onto the environment instead of making solutions that fit into it. The entire reason I keep dunking my head into the permaculture world is to fix that-to unlearn this tendency of forcing nature to submission, but instead to create buildings that acknowledge it’s place, humbly, in this vast world we were blessed with.
I’ll continue to keep my eyes and ears pealed to this growing Passive House technology. Any lessons gleaned from it I will seek practical use for what I am trying to achieve with this permaculture home concept.
My goal at Alt-Ark is to Make Homes More Permaculture, to help you build that permaculture house on the homestead.