What’s better than high tech? In a word (well two) no tech. This is the elemental argument for Passive House. I attended a very informative talk by Kat Kligenburg the Executive Director of the Passive House Institute US. The logics and economics of Passive House has been well developed and documented in Europe and now the case is being made for a US market.
Build a shell so well insulated and air tight that cooling and heating is seriously reduced, which in turn means the home does not require an active HVAC system. A building is developed using an elaborate energy modeling program that accounts for wall details, windows, doors, internal heat loads (like you are), external climate conditions, orientation, thermal mass properties, air exchange, and on and on. The end result is a home that eliminates the cost of HVAC.
So what does this mean in real terms when it comes to the decision making process of building? If you are aiming for cheap plentiful square footage then this is not for you. If you have that log cabin house in the woods with a great wall of windows in your mind then you are pushing your luck. If you are looking to build the most sustainable home that has an outstanding energy profile, and your are willing to give up a dormer or two you might have just hit the jack pot.
Right now America’s notion of “green” building is basically conventional building with a whole lot of gadgets hooked up to it. Maybe we’ll put in a 2x6 wall instead of a 2x4 and bump up the windows but the real strategy is almost always to pluck from the budget for high tech. Do a search for green building and you will be inundated with high tech stuff—condensing furnaces, solar thermal, boilers, radiant floors, SEER ratings, solar panels, geo thermal. All great solutions to keep an OK house comfortable.
The Passive House argument is that if you properly design and implement a super insulated envelope you eliminate the need for all this gadget wizardry. It really starts to make economic sense when you don’t need really expensive stuff like a ground source heat pump (aka the mislabeled geo thermal system) to make the house work. The project parameters change and frontend design work becomes critical, rather than plugging in equipment to a preconceive design.
Now extrapolate this thinking into the not so distant future. Your gee-wiz equipment is still using energy, aka costing you money and requiring maintenance. Counterpoint the Passive House model in which there is no required continuing operating cost, meaning lot less problems compared to the gee-wiz stuff buried in the mechanical room. I have seen a few really complex systems that will eventually develop expensive ticks. So dollar for dollar the Passive House makes a better economic and environmental choice. Well at least that is what Ms. Klingenburg will have you believe.
Ground source heat pump hydronic cooling and heating with solar assist:
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