Portland Cement Association has developed a touch-screen computer system that shows how the building materials used to construct a home's exterior walls impact its energy efficiency and comfort. The program — now on display at the National Building Museum's recently opened “Green House: New Directions in Sustainable Architecture and Design” exhibition — takes into account the size and geographical location of a house to determine what type of home construction materials provides the lowest annual energy use.

Homeowners can choose from a variety of products designed to make their homes energy efficient. Energy-saving dishwashers, light bulbs, windows and more help cut utility costs, but one of the most important factors in a sustainable dwelling is often overlooked — the walls. “The materials used to construct the exterior walls of a home have a significant impact on the cost of heating and cooling the home,” says David Shepherd, PCA's director of sustainable development. “For example, the thermal mass of a concrete wall system can reduce temperature swings in the home, thereby increasing the residents' comfort and reducing the need for extended use of the furnace or air conditioner.”

The touch-screen system reviews five house designs from 2,000 to 2,400 sq ft in eight U.S. cities. It allows users to compare 11 different wall systems, such as insulating concrete forms, wood frame with appropriate insulation, concrete masonry, or cast-in-place concrete walls. With this information, the program then estimates the annual cost for heating and cooling the home.

Presented by the Home Depot Foundation, the Green House exhibition runs through June 3, 2007, at the National Building Museum in Washington, D.C. PCA, along with the Foundation for the American Society of Interior Designers (ASID) and Bosch home appliances, are lead sponsors.