General Space Heating Systems Description

In this post I will give a general description of my space heating system. In the following posts I will discuss in more detail the individual system components. The primary source of heating for my house, which provides the vast majority of my yearly heating energy requirements, is the sun. The passive solar design of the house allows the house to be heated directly by the sun. Plenty of south-facing windows allow solar radiation to enter the house and heat up the interior. A large amount of thermal mass absorbs most of this solar radiation so that the internal temperatures do not quickly rise too high. The excess energy absorbed by the thermal mass is released during the cold night, thereby keeping the interior temperature warmer than the outside. An air-tight and well-insulated house envelope ensures that any heat energy leaches to the exterior very slowly.

Another primary, but very small, source of heat for the house is my renewable energy system's resistance air heater dump load. A dump load is an electrical load that uses up any excess energy produced by the wind-PV electrical system during the course of the day; the amount of heat energy produced is highly variable and depends on the combination of sun, wind, and energy consumption at any moment in time. This dump load is located in the central bedroom of the house. Another source of primary heat, but an even smaller one than the dump load, is waste heat from a number of sources. Electrical appliances but off waste heat for a variety of reasons. The refridgerator expels heat from within the fridge into the kitchen. The gas stove burners put off waste heat during cooking, as does the grill oven and other food cooking devices. Lights, televisions, laptops, radios, and other smaller electrical devices also put off waste heat. My wife and I put off waste heat, as does our house dog. Whenever I wash the dishes with warm water, take a warm shower or bath, or fill the bathroom sink with warm water to shave, waste heat is emitted into the rooms.

For periods of either extremely cold and/or cloudy weather, when the sun's radiant energy, combined with the smaller sources of waste heat and dump load heat, is not enough, a wood-burning masonry stove situated in the center of the south half of the house provides backup heating to supplement the sun's radiant energy. This soapstone masonry stove is only sized to provide heating for a more-or-less 50 m2 area (in this type of climate and with a high insulation envelope), so it is not capable of providing backup heat for the whole house. This wood-burner can be fired twice a day with a maximum total of 9 kg of wood burned daily.

Since the masonry stove is incapable of providing backup heating for the entire house, I sometimes have to resort to using a paraffin heater to keep the corner end bedrooms warm. The master bedroom gets heated more often than the guest bedroom because we use the bedroom on a daily basis whereas the guest bedroom is used only occasionally during winter and can therefore be left colder. We have two heaters, one manual and the other electric. The electric model turns the heater on and off automatically; it has built-in electronics that monitor the temperature, time and consumption and can be programmed to turn on at a set degree and off at a different set degree, to turn on at a certain hour and off at another, and to turn off when the paraffin level is low. These automatic features significantly help reduce paraffin consumption in comparison to a manual one.

I plan to build a sunroom to further exploit the sun for providing the home's heating energy requirements. The sunroom is an integral part of the original house design but is a feature that can be added on whenever. When I have the time and resources to build it, I will. This sunroom is an indirect passive solar heating system. The sun will heat the air within the sunroom to relatively high temperatures. This heated air will flow into the house, creating a negative pressure in the sunroom and a positive pressure in the house, both of which cause cold air at floor level within the house to flow into the sunroom, thereby creating a circular thermosiphon effect.

I also plan to build an active solar heating system for the house. This system will be composed of solar thermal water heating panels attached to the bottom half of the south wall within the sunroom. These panels will be attached by plumbing to special PCM-filled baseboard radiant heaters within the bedrooms and bathrooms. The PCM thermal mass will store excess solar energy for night time heating. The hot water will be pumped to the radiant heaters using a small pump connected directly to a small PV panel - when the sun shines enough it heats the water and runs the pump at the same time. No sun, no pumping of cold water.