Isolated Gain (Sunspaces)
This sunspace incorporates masonry thermal mass to store heat for later release when needed.
Photo credit: Donald Aitken.
The most common isolated-gain passive solar home design is a sunspace. A sunspace—also known as a solar room or solarium—can be built as part of a new home or as an addition to an existing one.
The simplest and most reliable sunspace design is to install vertical windows with no overhead glazing. Sunspaces may experience high heat gain and high heat loss through their abundance of glazing. The temperature variations caused by the heat losses and gains can be moderated by thermal mass and low-emissivity windows. For more information, see sunspace orientation and glazing angles.
The thermal masses that can be used include a masonry floor, a masonry wall bordering the house, or water containers. The distribution of heat to the house can be accomplished through ceiling and floor level vents, windows, doors, or fans. Most homeowners and builders also separate the sunspace from the home with doors and/or windows so that home comfort isn't overly affected by the sunspace's temperature variations. For more information, see sunspace heat distribution and control.
Sunspaces may often be called and look a lot like "greenhouses." However, a greenhouse is designed to grow plants while a sunspace is designed to provide heat and aesthetics to a home. Many elements of a greenhouse design that are optimized for growing plants, such as overhead and sloped glazing, are counterproductive to an efficient sunspace. Moisture-related mold and mildew, insects, and dust inherent to gardening in a greenhouse are not especially compatible with a comfortable and healthy living space. Also, it is difficult to shade sloped glass to avoid overheating, while vertical glass can be shaded by a properly sized overhang.