Whats the fundamental concept behind passive solar energy? Its not as esoteric as you might expect. Its just a matter of engineering, drawing up blueprints, and building or remodeling a home with an eye on taking advantage of the thermal energy of the sun. One of the upsides after the initial expense is that the utility company cant charge for the sun and the government cant tax it. Until they find a way to do it.
It is possible to use the sun in both the summer and the winter. This is a natural supply of energy and is one of the most sustainable from nature, at least until our sun goes super-nova. Dont hold your breath on that one.
First, Orient Your House for Maximum Thermal Advantage
It is obvious that it is trendy to make a feng shui compass reading and orient your house to multiply your happiness, luck, and even your wealth. It might be useful to point out at this juncture that feng shui remains the fortune cookie approach, at least until some proof can be offered.
That being said, orienting your passive solar windows in a range of approximately 30° due south is sure to go easy on your bank account, each and every time your energy bills lands in your mailbox. On an existing home you might not be able to take full advantage of this tip. Not to worry; there are many other ways to maximize your homes energy efficiency.
Why follow these geographical considerations? Because the rule of thumb is that the southerly side of your house will receive up to three times more sunlight than your westerly and easterly facing sides in the wintertime, and just one third as much during the warm summertime.
The concept behind this plan is to both minimize indoor overheating in the summertime and conversely maximizing the solar gain in the winter months.
If you happen to be renovating your home rather than undergoing new construction, it is worth thinking about upgrading and relocating energy efficient replacement windows.
Carrying this concept further, consider planting shade trees (not evergreens like pine) on the outside of these windows. This can offer effective shade during the hot summer, but shed leaves in the fall will allow the sunshines warmth to enter during the colder winter.
Remember not to plant trees too close to your foundation as the roots can invade them. To be proactive, install root barriers at the same time you plant your trees. Consider planting fruit or nut trees. Why not become a bit more self-sufficient?
Choose Your Building Material With Thermal Mass in Mind
Now that we have discussed your interface between the inside and outside for taking advantage of heat in the winter and avoiding it in the summer, how can we use trapped heat to our advantage in the winter?
Everyone knows what heat is, but recall from your high school physics what cold really is; it is not an thing unto itself, but rather is the perceived relative absence of heat, or thermal energy. Its just easier to use a word like cold than to say, when passing the time, "Boy, there sure is lack of heat today!"
Many materials have effective thermal mass. Good choices for absorbing and retaining heat are brick, concrete, ceramic tiles, and eco-friendly cork flooring. Even furniture such as your couch will act as a heat bank for you. These object are also called passive solar collectors.
Because we are retaining heat in the winter, building materials such as these tend to absorb and bank the heat (thermal energy) in the daytime and then slowly release it during night time, which will reduce the load on your heating system.
In a similar fashion, during the summertime, when you are restricting the heat that enters your house, these materials will remain cool to the touch.
To some extent, they will help you by absorbing a certain amount of the heat from the air in your rooms. And this will give your central air conditioning unit a much-needed break. By orienting your energy efficient windows to take advantage of passive solar concepts you are expanding your kit of energy miser strategies. Use it to your advantage.
A more scientific definition of passive solar concepts is just this—to redistribute energy collected according to one of the fundamental laws of thermodynamics, which states that heat naturally moves from warm to cooler locations and surfaces.
Adding Active Solar Collectors
While taking advantage of the sun for passive solar, know that you can, for an investment, employ active solar collectors. These are more complex than passive collectors described above. They are made up of flat-plate PV panels. These are normally mounted and remain stationary. There are some versions that are engineered to track the sun through the course of the day.
Some designs consist of multiple panels that are connected together in order to form modules. Active solar collectors may contain either air or an appropriate liquid to be used as a conductor. Those that use air are called air collectors, while liquid-filled ones are referred to as hydronic collectors. The evolved design of these collectors constitutes an active solar heating system that is very cost-effective in terms of lowering reliance on conventional energy sources.