Passive solar energy could handle all of a Midwestern home's heating and cooling needs, says one Ball State University professor.
"It's possible to have a comfortable building in Muncie, Indiana, that is 100 percent passive," said Alfredo Fernandez-Gonzalez of Ball State's Center for Energy Research, Education and Service. "More research will be conducted over the next year that should substantiate my initial findings."
Fernandez-Gonzalez studied five different passive solar concepts on Ball State's campus. Data shows Muncie's climate is comparable to much of the United States. By demonstrating that the concept works well in a cloudy, temperate climate, passive solar energy has a better chance of being accepted as a legitimate option.
For the study, five structures were constructed with a distinct passive element, such as a south-facing window and a floor of concrete blocks. Another structure had a window and columns of water, which proved to have great capacity to store heat.
One concept, the roof pond, posted the best results for heating and cooling. The structure has a window in the attic shielded with a mini garage door that, when opened, allows the sun to shine onto bags filled with water, similar to waterbed mattresses.
On cold days, the garage door is open during the day to capture the sun's heat, and it automatically closes at sundown to retain the heat. Now that it's summer, the door opens at night to release the heat and closes at daybreak to maintain its cool temperature.
The roof pond produced the most consistent temperatures throughout the study. It also maintained the warmest nighttime temperatures throughout the winter. And even on the warmest summer days so far, it has been able to keep its living area relatively cool.
To maximize the roof pond's effectiveness, it should be combined with direct gain, another passive solar concept that allows the sun to warm heat-retaining cement floors, Fernandez-Gonzalez said. Direct gain would complement the roof pond by helping the structure post warmer temperatures.
During the study, the direct gain structure posted the highest temperatures. Direct gain's abundance of warmth, combined with the temperature stability of the roof pond, could effectively provide 100 percent of a home's heating and cooling needs, Fernandez-Gonzalez said.
"Coupling the roof pond with direct gain is an attractive option that should provide superior performance," Fernandez-Gonzalez said. "In addition, the cooling potential of the roof pond makes it a viable year-round option. Continuing the experiments throughout the summer should confirm this potential."-30-
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