Doing More With Less: No Heat Wasted

A series of case studies illustrating cost-effective, sustainable design solutions that save materials, energy and water.

THE CHALLENGE:

Providing reliable domestic hot water for a gym on a college campus is a challenge, especially during peak hours when dozens of students are showering at once. The typical solution — a gas-fired water heater — was off the table for California State University, Dominguez Hills, which has committed to eliminating fossil fuels by 2045. Instead, for the new Health, Wellness and Recreation Center, the university wanted an all-electric system that aligned with its broader sustainability efforts.

THE SOLUTION:

LPA’s design team took a two-step approach, tapping into an emerging strategy for energy efficiency: waste heat recovery. The first step was integrating with the university’s newly upgraded heating water loop, which captures heat expelled from air-conditioned buildings and repurposes it for heating water. But that system only heats water to about 100 degrees — short of the 105–115 degrees required for showers.

To bridge the gap, the team designed a secondary heat-recovery system using heat pump water heaters. These units capture heat from inside the rec center — heat that would otherwise be expelled into the atmosphere by the air-conditioning systems — and use it to raise the water temperature the last 10–20 degrees. The final design includes four heat pump water heaters, working in tandem with the campus heating water loop to create a fully electric, zero-emissions domestic hot water system.

“Every ounce of energy used for hot water in this building is recovered or reused,” says LPA Senior Project Mechanical Engineer Doug Seamark. “There’s no such thing as ‘wasted heat’ anymore.”