Monday, November 29, 2010

What is net zero and is it something only Germans do?

Day by day now, before I go outside, warmer layers of clothing are added to keep out the chill. It would be nice if that's all we needed to do to keep our homes comfortable, just add on layers when it's cold, take them off when it's warm, but until someone quite smart invents easily removable woolly sweaters and Gortex jackets for houses, other methods will have to be employed.

Most people are familiar with insulation, air/moisture barriers, furnaces, hot water tanks. Even if someone's never stuffed spun glass batting in between two wall studs or taped up the seam between sheets of polyethylene house wrap, one's probably got a good idea of what this stuff does and how it helps keep the warm air inside from escaping outside too quickly. We all know that a well insulated, relatively air tight house is a more comfortable house and a cheaper house to run. What we hadn't realized, until recently, is that using a lot of these same old, easily understood technologies along with some newer building methods, we would be able to achieve some rather amazing results with respect to costs and efficiencies when it comes to maintaining a comfortable living environment inside our homes.

The passive house concept, first introduced in Germany (Passivhaus) in 1990, is a design philosophy and practice which is used to build highly energy efficient homes which require little to no energy for space heating or cooling. Combine the passive house concept with some energy generating equipment, like photovoltaic solar panels, for example, and suddenly not only do you have a super efficient house but one that actually produces as much or more energy than it consumes. Now you've got a net-zero house, referring to the net amount of energy the house uses which is not self-generated. For example, if a house uses 1000 kilowatt-hours every month from the local hydro grid (and uses no other external source of energy) but produces 1200 kilowatt-hours every month from its PV solar panels and feeds that generated energy back into the grid, then that house is considered to be a net zero house.

Not every house can be a net zero house - maybe the regional climate is just too severe, maybe there is no space for solar panels - but it's an ideal worth aiming for especially with new builds. According to Wikipedia, there are about 25000 certified passive houses in Europe, the majority of which are in Germany. On the other hand, there are only a few dozen in the United States. I'm sure those skewed numbers have got something to do with the Euro-centric certification process but still, it's indicative of who's ahead in this field and who's lagging.

In Canada, I don't think the situation is much better. This lacklustre performance is partly due to our historically cheap energy prices which created few incentives for people to be overly concerned about super efficient houses. It's also due to inertia in the building industry. Why change what is hugely profitable and ain't broke? And another part of the reason for the drought of net zero houses is the perceived costs involved with getting there.

Admittedly, if not planned properly, the pursuit of the net zero ideal can get pricey. It's easy enough to go overboard on the expenses by overloading on all the new technology that's out there now. There have been huge advances in the components that go into building more energy efficient houses, like super insulated wall systems, thermal solar panels for heating water or indoor air, quadruple paned windows, geothermal heating/cooling systems - all just the tip of a very large iceberg of technology - and all this tech usually comes with a hefty price tag. It can add up quickly. Sure, it may be relatively easy to build a net zero house if one has an unlimited budget but what's the use of that?

The point is to do net zero housing on the cheap, at least cheap enough that most people won't balk at the additional costs, cheap enough that the higher overhead pays for itself in a matter of years and not decades. Is this possible? We're here to find out.

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