In most parts of the world, space heating systems are installed in every home. They provide warmth and comfort during the colder part of the year. Unfortunately, the vast majority of these systems rely on grid-tied, non-renewable power sources to provide that heat. In a bid to reduce our environmental impact – not to mention our operating costs – we can use the sun's power to provide space heating.
There are two "top level" types of solar space heating: active and passive. An active system is one which uses a solar collector array to capture the sun's radiation and, through a variety of equipment, passes that heat to the home space as warmth.
Active systems are very flexible. They can run without any kind of storage or can include one or multiple tanks. They can integrate with other heat delivery systems, such as grid-tied backups. They can run on liquids or air. Whichever type you decide to install, an active system will reduce your grid-tied power bills, though it is unlikely you will be able to generate 100% of your heating needs purely through solar space heating.
Passive systems are those which are built into the home or which use the house itself as a solar collector. There is a very wide range of passive space heating options available, including everything from optimizing south-facing windows to a choice of heat-retaining floor tiles and colors or even appropriate construction materials.
Obviously, retrofitting passive systems can be a very expensive business. This is why they are generally considered (and should really be obligatory) in new builds and are rarely applied to existing buildings.
Most homeowners who wish to install solar space heating start by considering an active system. This makes sense but it's wrong: they are overlooking important, often small changes that could make a significant difference to their heating bill and, on top of that, will end up sizing a system that produces more energy than they really need.
It is always advisable to start any renewable energy effort by examining what you already have and seeing if you can adjust it to conserve energy. Most homes are built to minimum standards, so look for places to improve yours. Better windows, better insulation, a change in energy usage habits – all of these and many more simple options can save energy and money.
The more you can save and reduce your energy use before you size a renewable system, the less the installation will cost you and the quicker it will pay for itself.