Solar Sunspaces

The term “sunspace” is used interchangeably with “sunroom” and “greenhouse.” But there are differences between the three words, depending on intended use.

Sunroom is a general term for home extensions that utilize windows and natural light. While these living areas can serve as game rooms, reading rooms, and other personal sanctuaries, they don’t necessarily contribute to heating. Greenhouses, on the other hand, are specifically designed to retain heat for the purpose of growing plants. Optimal conditions for growing plants, though, aren’t optimal to living spaces. In addition, solar heating gains may be compromised in a greenhouse because high temperatures and excess humidity must be controlled for plant survival. Some attached greenhouse designs may even make a home use more energy if thermally poor windows are used to replace a well insulated wall.

Unlike sunrooms and greenhouses, solar sunspaces are built with the intention of collecting solar heat for distribution through the home. Because they can do this without the need for mechanical devices, they are a form of passive solar heating. Passive solar heating techniques are integrated into a home’s design and building materials, making for a cost-effective and low maintenance alternative to solar panels.

Solar sunspaces are considered to have a combination of direct and indirect solar gain. As attached rooms with the capacity to be occupied, they can be considered instruments for direct solar gain, where the space itself acts as the solar collector. Because the heat from a sunroom is intended to flow to the remainder of the house via shared walls or vents, they also comprise indirect solar gain, where the solar collection and storage area is thermally linked to the primary living spaces.

Solar sunspaces can even fall with the isolated solar gain category when they operate independently and are thermally isolated from the occupied areas of the building. In this manner, they can provide additional useable space outside the house. Sunspaces need dark-colored thermal walls 8-12 inches thick and summer ventilation to prevent overheating. If overhead glass is used, heat reflecting glass or shading systems in the overhead areas should be used. Also, directional orientation and the angle of window glazing should be considered. Because there is usually excessive glazing on sunspace windows, low emissivity varieties should be used to help prevent quick heat gain and loss.

More information about using sunspaces:

• Isolated gain solar
• Designing and Building a Solar Greenhouse or Sunspace