Water Efficiency Case Study: The General Services Administration (GSA) National Deep Energy Retrofit Program (Federal Headquarters Building, Washington, DC)
U.S. federal buildings represent the largest aggregate building portfolio in the world, accounting for billions of square feet in real estate. They not only provide space for hundreds of thousands of employees to provide critical services to our country, they also represent a significant opportunity to save energy, water, and money, create jobs, stimulate economic growth, and demonstrate building performance solutions that can drive the private sector forward.
This large Federal building was consuming 10,219,643 gallons of water annually at a cost of $158,394. The water was being used in the domestic plumbing fixtures; toilets, urinals, faucets and shower heads, along with non-domestic uses such as cooling towers and some manual irrigation. The largest use of water consumption was the cooling tower at 6,423,481 gallons.
The domestic water conservation measures included installing higher efficient toilets and urinals, flow restrictors in the lavatory faucets, and water efficient shower heads. The make-up meters on the cooling towers were replaced with sewer deduct meters, so the facility does not have to pay for sewer water that is not going out to the sewer.
The largest water saving measure for the building was capturing the ground water, filtering and treating it for cooling tower make-up. The building had a constant flow of 20-30 gallons per minute of water in the ground water sumps which was being discharged to the local storm sewer system. By capturing and re-using this water, the cooling tower make-up water is now almost solely from the reclaimed ground water.
A rainwater collection system was also installed. The system collects rainwater from 18,000 square foot of roof; this water is used for manual hand watering, as well as toilet and urinal flushing in one of the main restrooms.
The overall results in the water and cost savings were very impressive, coming in at 78% with almost 8,000,000 gallons saved annually, and a cost savings of $124,000. Most of the savings came from the capturing and re-using of the ground water in the cooling system.