Solar energy is a hot topic in buildings today. When you mention solar, many people think of photovoltaic (PV) panels mounted on the roof to produce electricity. This electricity can certainly be used by homeowners to offset the cost of heating and cooling, especially with electric equipment like heat pumps.
However, solar energy can also be used to directly heat homes, using either passive or active methods. See www.energysavers.gov/your- home/space_heating_cooling for more information about using the sun to heat and cool your home.
Active Solar Heating
Active solar heating uses solar collectors that heat water or air. The most common are solar thermal water heaters. These are typically used for heating domestic hot water. If you are planning to install a solar thermal water heater and have or are considering installing a hydronic heating system, you can check with your installation contractor on the feasibility and cost-effectiveness of connecting the solar water heating system with the hydronic heating system to heat or preheat the water.
Another form of active solar heating equipment is a room air heater which uses an exterior wall- or roof-mounted flat plate collector to heat air that is drawn from the room, passes through the collector, and is redistributed to the room. Combination systems are also becoming available that draw heated air from underneath roof-mounted photovoltaic panels to heat air and/or water via heat exchangers located in the attic. More information on active solar heating is available at www.energysavers.gov/your-home/ space_heating_cooling. Costs vary depending on system type, size, and components.
Passive Solar Heating
Passive solar heating uses a home’s design elements to take advantage of sunlight that reaches into the living spaces of the home. Passive solar design features like thermal mass walls and floors, sun rooms, and south-facing building orientation are most easily incorporated when designing a new home. However, existing buildings can be adapted or “retrofitted” to passively collect and use solar heat. The energy savings from passive solar heating are very dependent on climate. It may not be cost-effective to add passive heating features in a cold climate location with few sunny winter days. In hot climates the extra cooling load may offset any winter heat gains. Regardless of the climate, when considering passive solar heating options, know that you’ll have to take steps to minimize unwanted heat gain during the summer. This might include planting shade trees, adding awnings, or increasing roof overhangs.
- THERMAL MASS WALLS OR FLOORS – A thermal mass wall or thermal mass floors can be incorporated into a remodeling project. A thermal mass floor or wall is made of a material that will absorb and retain a large amount of heat, for example, a brick wall or concrete slab floor. The thermal mass is located where it will absorb sun through a large window for several hours of the day, then, because heat moves from hot to cold, the mass will release that heat gradually during the evening hours. In the morning, when the wall or floor has cooled, it will be ready to absorb more heat.
- SUN ROOM – A sun room or sun porch can be added that has large south, and possibly east- and west-facing windows. The sun room should be separated from the rest of the house by an insulated wall with openable doors and shaded windows so that heat can be let in during the winter and kept out to avoid overheating the house during the summer.
- SOUTH-FACING WINDOWS – If you are already planning to add or replace windows as part of a remodel and if you live in a cold
or mixed climate that gets adequate sun during the winter, you may want to consider adding larger, south-facing windows that can let in winter sun but are protected by overhangs, awnings, plants, or shades to keep out summer sun. The windows should be high-performance ENERGY STAR-rated windows to minimize heat loss.