Heating the interior of a house with the sun takes two forms: Passive Heating and Active Heating. Both are best suited to new construction since most older homes, even after an energy retro-fit, are still not energy-efficient enough to justify the investment.
Passive Solar Space Heating Systems
Passive systems for heating are simple in concept and have few if any moving parts. The idea is to trap solar radiation within the building during the day and store enough of it to keep the building warm during a cold winter’s night. The two basic elements you need are: south-facing glass and something to absorb and store all that heat after it has entered the house. The two most common materials for storing heat are masonry and water. Typically, for this to work, one-half to two-thirds of the total surface area in a south-facing room has to be built of thick masonry, or the house will overheat. Hmmm, it’s a bit daunting for most homeowners to contemplate a house with so much exposed masonry or concrete on the interior. A scaled-back version with perhaps a concrete floor or stone wall and not so much glass is more likely. In either case, it has to be part of every step in the building’s design from the initial concept. Another concern is night-time heat loss through the glass. Thermal window treatments to cover the glass at night is a good idea (even if you don’t have a passive solar heating system).
Active Solar Space Heating Systems
Active solar space heating systems use hardware and electrical energy to collect and distribute heat. The major elements are: a ground or roof-mounted solar collector, a separate water storage unit, and a low temperature distribution system, like radiant floors. Unlike passive systems, these systems can be more easily incorporated into new construction. But, like anything that is added to the house, the more you plan in advance, the better it will look and work.
Solar space heating makes the most sense in a new, air tight, well-insulated home where the heating load (amount of heat required over the course of a year) is brought down to a very low level.
Active solar space heating systems typically use roof-mounted or ground-mounted solar collectors that look like this: