Posted by Tim Stobbs on December 10, 2007
I have a very particular requirement when I’m looking to buy a house that always drives my real estate agent a little nuts. I always buy a house with as many windows facing south as possible. I do this for one main reason only: solar heating. I love to use free, all natural, and renewable heating where ever possible. Actually once you understand a few basics you can often get a fair amount of your heating needs from the sun even in the winter.
Now people often hear the term solar heating and assume you need complex equipment to make this happen when in fact passive solar heating needs very few things to make it happen. The most basic form of passive solar heating is remembering to open your drapes when the sun goes up and closing them when the sun goes down. Both parts of that are important. Most people tend to forget that windows which let in the sun’s heat during the day will immediately start releasing it our during the night because most windows have a very low insulation value. So investing in heavy drapes for the winter is a good idea to block drafts and help keep in that heat you built up during the day.
Beyond that there are a few factors that can improve passive solar heating performance: air circulation, thermal mass and sealing.
- Air circulation is one of the more overlooked parts of solar heating. If you can’t move the heat around to where you want it, it will just stay in your sunny rooms of the house near the ceiling. Perhaps one of the easiest ways to do this is use of a ceiling fan in your sunny rooms. By circulating the warm air down you will heat more of the cooler air in your home. So if you have a two story house, having a ceiling fan going in your stairwell when the sun is out will increase your solar heating by a fair amount. Additionally for those who really want to get the most out the sun, you might want to use a couple of additional fans to move the cooler air near your floor into your south facing rooms. Why move the cooler air in? Colder air is denser and expands when heated. So when you push in cooler air into a sunny room is gets heated, rises and expands and with no where else to go pushes out of your south facing rooms over top of your cooler air fan.
- Thermal mass is useful to retain the sun’s heat when it isn’t shining. The best materials for thermal mass include concrete, stone and tile. These materials when used indoors will absorb and store the sun’s heat and then slowly radiate it back out during the night. The thicker the material, the more heat it can store. The main issue for most people with this is it hard to add to a room unless you build the house. Another material also works well is water, but you tend to need large volumes of it to make a noticeable difference in a room.
- Sealing your home to retain extra heat lost to air leaks is a good idea, but can be a two edged sword. Since when you live in a home that is well sealed your not getting much for fresh air in the house. So if you do seal up your home very well I suggest investing in some house plants to help clean up the air and also opening a window periodically to exchange your stale air for some fresh.
Now your wondering how much heat can you really get from the sun. It depends where you live. Solar heating for example in Vancouver or Victoria wouldn’t be all the useful, but it can be useful just about anywhere in Saskatchewan. As to have useful it is, well yesterday afternoon with temperatures around -11C my furnace didn’t turn on for most of the afternoon because I had my drapes open and one ceiling fan on. For those who want to do a bit more reading I suggest starting here.