Green Home In Vermont

From The Times Argus (Montpelier, Vermont)


Article published Sep 27, 2009
Realizing the dream
Designing and building a green home in Vermont

As I began the process of designing and building a green home, I thought, "Building a green home just couldn't be all that difficult, right? Then how come no one around here seems to be doing it?"

To show local builders and homeowners just how accessible the process could be, I decided to use only locally available materials and skills. The project would meet both Energy Star and LEED criteria for maximum energy efficiency and minimal environmental impact. (The LEED — Leadership in Energy and Environmental Design — Green Building Rating System was developed by the U.S. Green Building Council as a way of encouraging sustainable building strategies.)

We had already framed up the house — the quickest part of the entire job. Next came the meticulous work of wrapping the exterior with extruded foam insulation, preparing the window openings, and taping and strapping the exterior. This created a waterproof, insulating layer under the siding known as the drainage plane, which keeps out any wind-driven rain that penetrates through the siding. This ensures dry siding on both sides, which means that it won't rot — and the paint lasts many years. The result is a low-maintenance and durable building skin.

Airtightness testing showed that all this work paid off handsomely. With help from Efficiency Vermont, we filled the house with theatrical smoke and then pressurized it with a big fan. Smoke was pushed out just a little at the windows and doors, but none escaped through the rest of the building envelope. The pressure meters confirmed that we had a very tight house. This feature, combined with high levels of insulation, sufficient south-facing windows and heat-recovery ventilation, gave a calculated heating requirement of one cord of wood per winter.

But this level of airtightness required careful design — and then rethinking on top of that.

When air is exhausted from a tight house (by a dryer or kitchen exhaust fan, for instance), the interior pressure drops. Outside air flows into this low pressure zone however it can. Without the usual cracks and air leaks, the outside air may flow down a chimney and bring toxic combustion gases with it.

For optimum energy efficiency, we wanted to keep the airtightness but solve the associated problems. First of all, we needed mechanical ventilation. Typically this is provided by a heat-recovery ventilator, which is simply a box with two fans — one blows stale air out and the other sucks fresh air into the house. The two airstreams pass by each other on opposite sides of a thin membrane so that the outgoing warm air can heat up the incoming cold air. The fresh air can then be ducted anywhere in the house.

Next we focused on the combustion appliances, which must be directly vented to the exterior for both intake and exhaust. Unlike most wood stoves, which draw their air from the room, the stove we were using had a fitting for an outside air duct to supply the firebox and ensure that the stove would always have a plentiful supply of combustion air drawn directly from outside. The gases in the chimney, stove and air inlet would be connected to the exterior only, so they wouldn't be affected by potential low pressure inside the house.

The dryer is usually double trouble. If it's electric, the fuel cost is high. But a gas dryer presents the combustion air problem. Either way, an air inlet is required to make up for the exhaust air. In winter, very cold air will be introduced this way. A solar (clothesline) or wood-fired (indoor rack) dryer is a simple, low-maintenance solution. The high-tech solution is a new condensing dryer, which does not exhaust but recirculates the air moving through it.

To conserve water, pumping energy and heating energy, we planned to install low-flow fixtures and a composting toilet. We fitted the sinks and showerheads with low-flow aerators. But the composting toilet was another cost casualty. The house was already connected to a state-permitted community leach field, and the extra cost wasn't justifiable. Instead we used dual-flush toilets that conserve water at both high and low flow rates. And we installed a solar water heater to provide hot water. Our plumber, Jay Smith, had just been certified by Renewable Energy Resource Center of Vermont (RERC-VT), so the hot water heater qualified for a nicely sized rebate.

We sought to minimize the building's electrical demand by making maximum use of daylight and using Energy star appliances, compact fluorescent and LED fixtures. Many of these fixtures qualify for rebates from Efficiency Vermont. The LED's are terrific: 60 watts of incandescent equivalent for 12 watts, a 5-to-1 savings!

Originally we had planned to install a rooftop photovoltaic system to meet the electrical requirements of the house. But in the end we were forced to eliminate the PV system because our budget didn't allow it. That may be just as well, because now the whole neighborhood is considering a shared community, net-metering PV system. Vermont's new net-metering legislation allows homeowners to build a renewable system and sell electricity back to the utility. This makes it possible, in the long term, to zero out your power bill.

Betti Jaquay, our painter, finished the interiors simply and cleanly. We avoided materials that would release toxic fumes (volatile organic compounds) and stuck with low-VOC paints and adhesives, or non-VOC materials like hardwood, linoleum floors and solid wood cabinets.

All the materials were purchased locally — including the solar equipment — and all the techniques were familiar to the builders. There is definitely a learning curve, but any contractor can build a house like this. Just get everybody on board at the start and follow these few simple rules for building a green house:

Buy local.

Think small.

Put it in the right spot.

Make it tight and insulate.

Use good quality, low energy materials.

Make it beautiful, adaptable and durable.

Michael Beattie, an architect, lives in Middletown Springs and be reached at mbeattie.arch@gmail.com. This article is the third in a series that covers the entire process of designing and constructing the green home. For Parts 1 and 2, see the articles on pages B4 and B2, respectively, of the June 14 and July 19 issues.

Visit the green home during an open house on Sunday, August 16, 1:00 till 4:00 p.m. Call 235-2468 or email mbeattie.arch@gmail.com for information and directions.

ON THE NET

Vermont Green Building Network

www.vgbn.org/

Renewable Energy Resource Center

www.rerc-vt.org/

http://www.timesargus.com/article/20090927/ENVIRONMENT/909279992/1033/ENVIRONMENT