Marilyn Blizard and Passive Solar Design

To get the most from her Kiawah Island home, Marilyn Blizard thought “sun.” The bountiful sunlight on the island was used to heat and cool her home and reduce energy use. More importantly, the energy from the sun made her house comfort-able all year round. There are two types of solar design systems - passive and active. Marilyn focused on passive solar design because the basic design principles and elements are easily incorporated into the Kiawah Island home site design process. In fact, many historic homes in nearby Charleston, South Carolina, use these concepts for cooling today. Marilyn’s home uses the natural movement of heat and air to maintain comfortable temperatures, operating with little or no mechanical assistance, although she also has a closed loop geothermal system to heat and cool. This passive solar design of the home maximizes the benefits it receives from the sun with standard construction features. Passive solar also takes advantage of the island community’s breezes, and the island’s east-west orientation provides a number of home sites with southern exposures. Landscape features on Marilyn’s lot, such as native shade trees and natural windbreaks, help to keep temperatures in the home moderate. In addition, passive solar uses a simple system to collect and store solar energy with no switches or controls. Although building a passive solar home takes careful planning, Marilyn says it’s relatively simple if one uses the following principles and guidelines: Orientation - Because the sun rides lower in the southern sky in the cooler months, there is no substitute for a building site with a southern exposure to assist with heating. Studies have found that orienting a house within 20 degrees of the south can cut a home’s total energy use by 30 to 40%. It is important that the areas most frequently used in your home are included in this southern exposure. Still, the electric cost to cool a home in this southern community is much greater than the cost to heat the home. For that reason, Marilyn encourages geothermal as the smartest way to go green. The local electric cooperative here offered a program to help Marilyn establish a geothermal system as a major electric bill saver. While it cost more to install, it paid for itself in four years, which Marilyn says was one of her best investments. Her geothermal uses a closed loop to take full advantage of the natural earth temperature of 67 degrees, providing winter warming and summer cooling. Window Design - Windows (also called apertures) act as the solar collectors and let in breezes when cooling is required. Limiting the number of windows on the east, west and north sides helps to insulate Marilyn’s house against winter cold. Windows must also easily open and close to facilitate circulation of the island’s breezes, as needed. Overhangs and Shading - While we want the sun to enter the home in the cooler seasons, we must keep the hot Kiawah sun off the apertures during the summer. Overhangs are one of the best, and least costly, ways of achieving this goal. In the summer, when the sun is high in the southern sky, the overhangs in Marilyn’s home shade the room completely. Keep in mind that the best scheme to keep a house cool is to not let it get hot in the first place. Use cove panels over skylights, exterior shades and awnings, and properly placed trees and trellises on east, south and west sides of your home to shade windows. Insulation - A well-insulated, energy-efficient house helps maintain an even temperature all year round. Moreover, a well-insulated house enables the passive thermal-distribution system described below to work properly. Insulation also includes the types of windows used in your home. Thermal Mass - All of the principles listed above could be included in any well-designed Kiawah home. What sets a passive solar system apart is the thermal mass. Thermal mass, a solid or liquid material, absorbs and stores warmth and coolness until needed. Thermal mass is an owner’s choice and may take numerous forms such as brick, tile or thick concrete floors. It could also be a large brick or stone internal fireplace or an interior wall of adobe or brick. Distribution - In winter, the thermal mass absorbs heat during daylight. At night, the thermal mass distributes the warmth to the home by radiation, convection and conduction. For example, Marilyn’s fireplace flue is exposed to take advantage of warming her wintertime home. In the summer months, the thermal mass is shaded and draws the warmth from the surrounding air. At night, it again distributes coolness to the home through the aforementioned methods. Marilyn’s architect was working to assure her home was designed to maximize the distribution of warmth and coolness throughout, including the use of adjustable ceiling fans to move the warm air towards or away from human airspace depending on the season. Another simple step is to have interior doors installed with one-inch space at the bottom to allow cool air to flow easily to even the house temperature for comfort. Building to take advantage of solar energy does not have to cost more than a conventional home. A properly oriented, well-insulated home with thermal mass and operable windows for air circulation will be both comfortable and relatively inexpensive. Using passive solar energy will also help to support our environment. Please visit the US Department of Energy website at http://www.eere.energy.gov/ for additional information about using passive solar design. Marilyn’s other “green” accomplishments are many. A new clothes drying rack outdoors takes advantage of breezes and sunlight! Best of all, it uses no electricity and was purchased at the local hardware store [shop locally to save energy]. Her floors are a gorgeous recycled maple. And, pots on the patios-away from the reach of local wildlife-are appropriated for growing vegetables. Marilyn values her community, which as she puts it, “cares as much about the protection of the natural environment as it does about aesthetics issues.”

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