Building ‘Net Zero’ Houses

By Beacon Staff

Most American homes today are energy pigs that, as fuel prices continue to increase, become more burdensome to their owners every year. They leak warm air out of every nook and cranny, have inefficient mechanical systems (that probably need a filter change), old light bulbs and water heaters, cold windows, and not enough insulation. Compared to the advanced technology employed in today’s autos, our homes are still stuck in the technology and practices of the last century, if not the one before that. A recent Canadian Mortgage and Housing Association study opined that, in the last 50 years, “no other large consumer product has changed so little in appearance, function, and performance as the single family house.” Simply stated, most of the important goals of today’s green building movement are meant to reduce waste in every way. How much energy do you want your home to waste? The next time that you pay your power or natural gas bill, take a minute to ponder just what percentage of that payment is OK to waste.

One of the important movements in the construction industry today is the focus to build what are called “Net Zero” houses. The Department of Energy sponsors a program called the Builder’s Challenge whose mission is to educate and encourage the building community to provide homes by the year 2030 that generate as much energy as they use, therefore requiring “zero” energy annually. This may sound a bit far-fetched, but Net Zero homes are currently being built all around the country.

Green builders have three tools in their toolbox to achieve this sort of energy goal. As always, the first stop is conservation of energy by airsealing and insulating to achieve airtight, high-performance envelopes that reduce wasted BTUs. Think of “house-as-thermos” and you start to get the idea. My company completed a high-performance 2000SF house this winter that, in conjunction with a well-insulated airtight envelope, had a ground source heat system to provide indoor air heating as well as pre-heating the hot water supply. The home also had a heat recovery ventilator for warm fresh air changes. A separate electric meter on the heating system allowed us to monitor its power consumption. In the six weeks since the end of January when the new owners moved in, it has used a little less than 140 KW for heating, which translates to around $8 (or $1.50 per week) – an almost laughably low number. Such minimal energy demand makes Net Zero seem very attainable, as well as affordable.

The next step to Net Zero is energy collection – the best example of this being solar hot water systems wherein the sun’s radiant energy is collected for domestic hot water supply. These solar water systems are extremely common is Europe (where energy costs are much higher than in this country) and are a very good performance value even in our cold northern climate.

The last tool that we have to get to Net Zero is electrical generation by photo-voltaic (PV) solar panels, hydroelectric, or wind power. Since we don’t have eastern Montana’s wind here, PV makes the most sense locally, especially as the price of panels comes down as the solar industry scales up.

To be clear, Net Zero homes are attached to the utility grid – you don’t have to worry about your batteries going dead while you are reading in bed. Power generation while grid-tied requires “net metering” – sometimes you are using the utility’s power, other times you are selling electrons back to them because your home is generating more than it is using. Wouldn’t it be nice to get a check back from the utility at the end of the year rather than a bill? To get to a Net Zero future by 2030, there’s no better time to start than now.

Len Ford is president of Ford Construction Corp, a NAHB certified green builder, and chairman of the FBA Green Build committee.