Our house is laid out and designed in a way to minimize the amount of energy needed to heat the structure, and to keep a comfortable temperature inside. Unlike a traditional house, the layout and construction of our dwelling is by far the most important component of our heating and cooling system.
Our design consists of two major elements: thermal mass and earth-bermed passive solar construction. Thermal mass, in our case a thick concrete slab and cinder block walls, acts as a giant heat sink. The masonry and cement slowly absorb heat during warm periods, and release it as temperatures drop. In practice, the thermal mass smoothes out extreme temperatures, keeping the indoor temps relatively stable year round, like a small-scale lake effect.
Because more than half of the house is earth-bermed (aka buried), there is minimal heat loss through the walls and temperatures naturally remains stable. The coldest they can ever get is ground temperature, which remains in the low 50s year round. Heating up the house to comfortable temperatures requires less heat than if the walls all led to the outside, which can get as cold as -15 in the winter. Conversely, the house is cooler in the summer, when outside temperatures can get up to the 80s and 90s.
Passive solar design uses the natural heat of the sun to warm the structure. Our house faces true south (slightly off from magnetic south [calculate your magnetic declination here]), and large windows allow ample space for sunlight to penetrate. In the winter, when the sun is low in the sky, sunlight reaches deep into the house, heating up our cement floor and thermal walls. On sunny days, our house requires no supplemental heat to stay warm, even in the depths of winter. In the summer, when the sun is higher in the sky, our extended awnings keep direct sunlight from hitting the floor, keeping the structure cooler. Keep in mind that passive solar design is most effective when combined with thermal mass. A normal passive solar house would gain all the heat benefits of a sunny day, but that heat would dissipate as soon as the sun hid behind a cloud or set for the day. The thermal mass absorbs the solar heat and releases it slowly over many hours.
Unfortunately, the sun can be scarce in the Finger lakes come winter, and temps can drop below zero. So while our design handles most of our heating needs, we also have two wood stoves for supplemental heat. In addition, we laid PEX tubing directly into our concrete floor to create a radiant floor heating system. Once it’s hooked up, the tubing will carry warm water through the concrete, heating the concrete slab and slowly radiating the warmth up and into the house.
Unlike fossil fuels, wood is a renewable resource that is carbon neutral, and can be locally sourced. Burned in an efficient stove, wood is a clean-burning, efficient source of heat.