The most energy-efficient building in the United States, according to the Department of Energy (DOE) and the Environmental Protection Agency (EPA), uses an Ice Bank® thermal energy storage system from Calmac Manufacturing Corp., Englewood, NJ.

The Centex Building at the International Center in Dallas, TX, has earned a score of 99 (out of a possible 100) in the EPA/DOE Energy Star Building rating system — the first building in the country to achieve that rank.

The Energy Star program rates energy performance based on actual energy use, which makes it possible to compare the overall efficiency of buildings nationwide. Buildings with a score of 75 or more earn the right to display the Energy Star label. The program monitors these buildings for a period of one year to determine actual operating performance.

Engineered and developed by Harwood Management Services, a member of Harwood International Corp., the Centex Building was designed by architect Richard Keating as the corporate headquarters for Centex, a residential home developer and construction contractor. The Centex Construction Group was construction contractor for this project.

The building consists of 176,384 rentable sq ft plus a parking garage of 180,000 sq ft. While utilizing many energy-saving features from lighting to insulation, a key part of the building’s efficiency is attributable to its cooling system. By combining thermal energy storage (14 Ice Bank tanks) with a Trane screw-type water-cooled chiller, the building’s peak electrical load is significantly reduced.

The advantage of thermal energy storage is that it shifts electrical usage to inexpensive off-peak hours; it is also said to reduce energy usage.