The Federal Energy Management Program (FEMP) provides acquisition guidance for gas storage water heaters, which are an ENERGY STAR-qualified product category. Federal laws and requirements mandate that agencies meet these efficiency requirements in all procurement and acquisition actions that are not specifically exempted by law.
Most manufacturers display the ENERGY STAR label on complying models. For a model not displaying this label, check the manufacturer's literature to determine if it meets the efficiency requirements outlined by ENERGY STAR.
Performance Requirements for Federal Purchases
For the most up-to-date efficiency levels required by ENERGY STAR, look for the ENERGY STAR label or visit ENERGY STAR product specifications.
Buying Energy-Efficient Gas Storage Water Heaters
ENERGY STAR's product specification applies to residential gas storage-type water heaters with capacities between 20 and 100 gallons, first hour rating (FHR) of 67 gallons or higher, and maximum energy input of 75,000 Btu per hour. Commercial and condensing gas water heaters are excluded.
The federal supply sources for gas storage water heaters are the General Services Administration (GSA) and the Defense Logistics Agency (DLA). GSA sells water heaters through its Multiple Awards Schedule program and online shopping network, GSA Advantage! DLA offers them through the Defense Supply Center Philadelphia and online through DOD E-Mall. When purchasing gas storage-type water heaters, choose models that are ENERGY STAR-qualified.
These requirements apply to all forms of procurement, including guide and project specifications; construction, renovation, repair, energy service, operation and maintenance contracts; lease agreements; and solicitations for offers. Energy performance requirements should be included in all evaluations of solicitation responses. Buyers shall insert the standard clause from FAR section 52.223-15 into contracts and solicitations that deliver, acquire, furnish, or specify energy-consuming products for use in federal facilities. Agencies can claim an exception to these requirements through a written finding that no ENERGY STAR-qualified or FEMP-designated product is life cycle cost effective for a specific application.
Storage-type water heaters are common, but they are inefficient due to high standby losses. Other more efficient options that federal buyers may want to consider include:
Tankless Water Heaters: Also called demand or instantaneous water heaters, these products heat water as it is needed. Absence of a storage tank reduces standby losses and can therefore increase overall hot water system efficiency.
Indirect Water Heaters: A space heating system that also provides hot water. In this type of system, hot water is typically circulated from a home's boiler through a heat exchange coil in a separate insulated tank. Domestic hot water is drawn from this storage tank.
Integrated Water Heaters: A hot water heater that also provides space heating. In this type of system, the hot water heater is connected to a coil in the air handling unit. Hot water is circulated through this coil whenever space heating is needed.
Solar-Assisted Water Heaters: A water heater connected to a solar collector that, depending on sky conditions and location, can meet most, if not all, of the hot water requirements. An instantaneous or storage-type water heater is used to meet excess demand or demand during extended periods of cloudy weather.
Depending on climate and energy costs, these options can provide energy and cost savings. To work properly, however, they require additional analysis and design.
Storage-type water heaters must be sized properly. Oversized water heaters not only cost more to install but increase energy use due to excessive cycling and higher standby losses. The American Council for an Energy Efficient Economy (ACEEE) publishes the Consumer Guide to Home Energy Savings that contains a chapter on water heating and provides guidance on proper sizing. A water heater should be selected based on FHR, not tank size. Some water heaters with small tanks and large burners have higher FHRs and are more efficient than models with larger tanks.
Energy costs increase with temperature. Dishwashers require the hottest water of all household uses, typically 135°F to 140°F. These devices, however, are usually equipped with booster heaters to raise the incoming water temperature by 15°F to 20°F. Setting the water heater between 120°F and 125°F and turning the dishwasher's booster on should provide sufficient hot water while saving energy and reducing the chances for scalding.
Estimating Energy and Cost Savings
FEMP provides a cost calculator for water heaters. This calculator allows the user to input site-specific values for energy factor, recovery efficiency, and the rate for natural gas. The output section will automatically display results that better reflect your energy costs.
Lawrence Berkeley National Laboratory provided supporting analysis for this acquisition guidance.