Solar Heating in Homes

Direct gain is a form of solar heating that involves opening the curtains of south-facing windows and letting the sun's light shine in, warming the room. If the walls are made of masonry or any other dense material, it will absorb heat throughout the day and slowly radiate it back at night. You can also use tanks of water to absorb heat, although this requires maintenance to prevent the growth of algae. Direct gain is the cheapest and easiest solar heating option, but it's also the least effective in that it only heats specific rooms for a short period of time each day. (See References 1)

Another form of passive solar heating is indirect gain, such as with a Trombe wall. Create a trombe wall by painting an exterior, south-facing masonry wall a dark color, and install sheets of glass a few inches away from the outside wall. This creates an insulating air space, allowing the sun's heat to pass through and warm the wall but preventing the heat from radiating back out once the sun goes down. Instead, the heat radiates through the wall into interior rooms, providing long-lasting warmth during the nighttime hours. The U.S. Department of Energy estimates that heat will travel through dense masonry at a speed of 1 inch per hour, so a wall 8 inches thick will provide heat well after the sun goes down. (See References 2)

Active solar heating systems are the most effective way to heat your home using the sun's energy, but they can be the most expensive and difficult to install. First, you must install solar collectors on your roof to harness the sun's heat. In an air-based system, this heat transfers to interior ducts, warming air as it moves through your home. Some units use liquid as the transfer medium instead, pumping this fluid through pipes installed in interior walls to warm your home from the inside out. (See References 3).