As with all forms of solar power – solar thermal, PV panels, solar chimneys and others – the amount and quality of sunlight to which a home is exposed is extremely important in holistic home design. Thankfully, again in common with many other forms of solar power, even areas that might appear at first sight to be far too gloomy can, in fact, provide enough energy to reduce heating bills by 50% or more.
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When you read about solar systems, especially solar thermal and passive systems, you may come across the "10-Degree Rule". The rule states that, wherever possible, a building should be constructed with the long axis facing within 10 degrees of true south (not magnetic south).
The reason for this rule is very simple: south-facing walls get the most sun (in the northern hemisphere). You want as much of a building as possible facing that way to gather as much heat and energy as possible.
The best advice is often the advice you hear every time you ask a question. In the case of solar energy, the best advice is always "fix everything you can fix before you start planning your project". If you plug all your leaks, improve your energy efficiency, and insulate your home properly, your solar energy installation can be smaller and will cost you less.
The single most widely applicable passive solar design option is thermal or Trombe walls. The option works in every climate and every location, from the hottest and sunniest to the coldest and darkest. But like everything, Trombe walls have their disadvantages as well.
Air quality is a serious concern, especially in retrofits and buildings where air pollution is particularly bad. The answer to the question of whether you need air filters depends on a variety of positive and negative influencers. Let's start with the positives:
Sunspaces – especially those attached outside the main home – are extremely popular. However, like all things, you need to carefully consider the benefits and disadvantages rather than just jumping in and building one.
Whatever air filter system you decide to install, you will have to decide what type of filter to put in. Air filters come in three types: gas, particulate, and hybrid.
Used in homes suffering from any sort of gaseous air pollution, these filters remove all sorts of volatile organic compounds outgassed by carpets, paint, engineered wood, and furniture.
Almost every passive solar building has a backup heating system, whether it's really needed or not. It is possible to design a passive solar home that heats itself, but it may not pass local building regulations. It will also be very hard to sell, as most home buyers simply won't believe that the house needs no heater other than the sun!
There are five options commonly available as backup heating for passive solar homes:
If your home's air pollution problems cannot be completely solved by eliminating and isolating sources of pollutants, you will need to install some kind of air filter. Whether that is a small, portable unit for occasional use or a large, whole-house ventilation system depends on how bad the problem is.