Masonry Magazine August 1981 Page. 11
Builders Use Passive Solar with Masonry, Help Homebuyers "Invest in the Sun"
The American homebuyer now considers energy efficiency to be a top priority in determining the value of a new home, and research conducted by the International Masonry Institute indicates that increasing numbers of builders are choosing to meet this demand through "passive solar" homes built with masonry.
By taking advantage of the tremendous power of the sun-which daily showers the earth with many times more energy than we need-a properly designed passive solar system typically can save 50 to 60 percent of a home's heating costs, saving money for the homeowner as well as constituting a more attractive resale.
The increased emphasis homebuyers place on energy efficiency is demonstrated in a recent National Association of Home Builders survey which indicated that, although only 60 percent of the people who bought homes in 1977-78 rated energy features as important, nearly 80 percent of these individuals will consider energy efficiency to be a top priority in buying their next home.
Many homebuyers are turning to the sun for their residential energy needs. A U.S. Department of Energy spokesman estimates that the number of homes with passive solar features may exceed 56,000 this year, more than double the number that existed in 1980. He also projects that by 1986 this figure could be as high as one million.
According to the International Masonry Institute, masonry is an ideal material for a passive solar building, not only because of its energy efficiency but because of its durability, low maintenance, fire resistance, residential "scale" and beauty, and time and cost-saving features.
In heating a home "passively," the energy of the sun enters the building to be used immediately, and it is also collected and stored for release at night. The heat is distributed by natural means-radiation, conduction and convection. In a passive solar system built with masonry, there is no need for mechanical equipment such as fans or pumps to move the heat throughout the structure.
There are a number of variations of the passive solar system. In the "indirect gain" system, a heavy masonry wall, called a "Trombe wall," is placed 2 to 4 inches inside a south-facing window or glass wall. As the wall heats up, thermal energy begins to flow through the wall toward the interior, releasing heat through radiation when the wall temperature exceeds the interior air temperature.
Vents can be added to the top and bottom of the wall to allow some heat to immediately enter the structure through natural convection. Because of the "time lag" property of masonry-its tendency to hold heat for a long time and release it slowly-heat continues to be radiated to warm the interior air during the night.
The system can be "fine-tuned" by selection of the size of the wall, size of window area or glazing, area of vents, and surface color. In the summer months, when the sun is higher in the sky, an overhang projected from the roof protects the home from excessive heat.
Fuel cost savings resulting from passive solar energy systems vary according to factors such as design, orientation, location and climate. These savings can be expected to improve as the costs for home heating and cooling increase; for example, for residential use of electricity, natural gas, heating oil and propane, the Department of Energy projects that the average increase over the next four years will be more than 10 percent per year in real dollars.
View of the living room, as seen from the kitchen, in the passive solar masonry home built by Anders, Inc. in Waukesha, Wis. During winter, heat from the sun is stored by concrete block and brick and released into the interior of the house at night. Heat savings in the structure are estimated to be 59 percent over conventional designs.