While oil is being drilled on far corners of the globe, we all have free solar energy falling on our properties. When my family moved into an ultra-energy efficient home in Belfast Cohousing & Ecovillage, a 36-unit community in coastal Maine on 42 shared acres, we started using this solar energy to heat our home and produce electricity.
All the homes in the community use 90 percent less energy to heat and cool than the average code-built home. Appliances, the sun, and occupants provide a majority of the heat needed to keep our home warm in our cold climate.
It’s fulfilling to know that we are harvesting the solar energy that falls on our property, both passively with large south-facing windows and actively with a solar system. Even in our cold climate where most homes are heated for 7 or 8 months of the year, all our energy needs are met by a winning combination of an energy-efficient design and solar energy.
Solar Orientation
During sunny winter days, our heaters remain off, as the sun gradually warms the home. The electric baseboard heaters kick on as needed, primarily at night or on cold, cloudy days.
All the homes have a rectangular shape, with the long sides running east to west. This enables the houses to capture as much solar energy as possible to significantly reduce the need for heaters, even in our cold Maine climate. The living rooms are lined with large windows, which also brings daylight into the home and reduces the need for supplemental light during the day.
Lots of Insulation
Belfast Ecovillage homes have structural insulated panels (SIPs) along all exterior walls. They consist of insulating foam which is sandwiched between oriented strand board. This allows for continuous insulation, eliminating gaps where heat can escape in the winter. Starting with the foundation, the entire exterior of the home is insulated either with foam or blown-in cellulose.
Thermal Mass
To help maintain the warm temperatures, thermal mass helps retain the heat. Objects with high thermal mass slowly absorb and retain heat. The thermal mass of the cement slab in our homes regulates the temperatures, releasing heat when the air above it is cooler than the slab, and storing heat when the slab is colder than the air around it.
Airtight Construction
Our homes are virtually airtight. All the seams in the house are sealed to prevent air from entering the home. Although this boosts the efficiency of the house, it would create air quality issues if there wasn’t mechanical ventilation.
To ensure high indoor air quality and comfort, our home has a Zehnder heat recovery ventilation system. Because the home is airtight, mechanical ventilation is essential for fumes, odors, and moisture to exit the building. A constant stream of fresh incoming air is filtered and preheated — recycling up to 90% of the heat from the exhaust air.
Household Energy Uses
Before installing a photovoltaic solar system, we examined how we could further reduce our energy use. We replaced halogen and incandescent light bulbs with LED bulbs, installed a low-flow shower head to lower our hot water use, put our hot water heater on a timer to reduce standby loss, and removed the screens from the south-facing windows during the winter for increased passive solar gain.
Have you employed an of these in your home? Have other solutions you utilize? Share your experiences in the comments section below.
Feature image courtesy of Jeremy Levine