Winter Comfort in a High-Performance Home
I’ve always had a love-hate relationship in the past with the heating systems in my home. As the fall temperatures started to dip, I loathed turning on the furnace each year. If we programmed the thermostat to have lower nighttime temperatures, then we were greeted each morning with a blast of warm air. Even with a humidifier on our forced air furnace, our home would become drier when the furnace was turned on in the winter, and I would cringe when thinking of the fossil fuel use needed to keep our home warm.
All of this changed when we moved into a high-performance house at Belfast Cohousing & Ecovillage, a 36-unit multigenerational community in Midcoast Maine. Our new home uses 90% less energy for space heating and is largely heated by the sun. On clear winter days, our home heats up gradually from the sun’s rays, as daylight streams in through our large triple-pane windows and doors. Our home is often several degrees warmer than the thermostat setting because generous amounts of insulation and air sealing keep the elements out. Even on cold, windy winter nights, I can sit in front of the windows and feel no drafts, a luxury that isn’t possible in many homes.
“We used to live in a home that was built in the 1860s,” explains Don Pan, a member of Belfast Ecovillage. “The house leaked like a sieve, especially around the window frames. We used to sit in the middle of the room because it was too drafty to sit in front of the windows. In our new [ecovillage] home, none of this is a consideration.”
Because the homes at Belfast Ecovillage are so well insulated, appliances and occupants help to heat the home. Cooking a meal and running the dishwasher make a noticeable difference. Even a few minutes of exercise with the kids can raise the indoor temperature a degree or two.
It has already snowed twice in Maine, but we have barely turned on the heat. Despite below-freezing temperatures at night, the bedrooms have recently been 70 degrees in the morning, with no supplemental heat.
After a nearly five-day power outage last December, with some sub-zero weather, indoor temperatures had dipped by only 10 degrees before the outage ended. Neighboring homes were below freezing after a mere 24 hours. It was such a relief to not worry about our pipes freezing.
The temperatures throughout the home are also very even, although this results in part from zoned heating. Our north-facing bedrooms don’t receive the same amount of passive solar gains as the south-facing living room and kitchen, but the entire house is comfortable.
Our Zehnder heat recovery ventilation system draws stale air out of the kitchen and bathroom and supplies fresh air to the bedrooms. High-efficiency heat recovery ventilation systems can be 85 to 95 percent efficient thus they are far more efficient than exhaust fans because the heat from the outgoing air is transferred to the incoming air before it exits the home.
In leaky homes, outside air is constantly entering the home, which provides ventilation but adds to the heating bill, as the incoming air is the same temperature as outdoors. Because our home is virtually airtight, the air quality would be poor without mechanical ventilation. The system allows the home to achieve high levels of efficiency while maintaining air quality.
The heat recovery ventilation system brings a constant flow of fresh air into our home, but it’s preheated to within several degrees of room temperature by the recovered heat from the outgoing stale air. Be aware that some heat recovery ventilation systems are less energy efficient and therefore may provide air that is noticeably colder than room temperatures.
In our last home, I could get a rough sense of the outdoor temperature by sitting in front of a drafty window or noticing how much our forced air furnace had to work to keep the home warm. Now I have to watch the facial expressions of our neighbors through our three large living room windows to gauge the outdoor temperature because our home is always comfortable and warm.