The Federal Energy Management Program (FEMP) sets federal efficiency requirements and provides acquisition guidance for residential electric resistance water heaters. Federal laws and requirements mandate that agencies meet these efficiency requirements in all procurement and acquisition actions that are not specifically exempted by law.
This product overview offers efficiency requirements for residential electric resistance, storage-type water heaters with capacities of 20 to 120 gallons and maximum energy input of 12 kW. Residential heat pump and gas storage water heaters are covered by ENERGY STAR. Boilers, swimming pool heaters, and instantaneous-type (also know as demand) water heaters are excluded.
Energy Efficiency Requirements
Federal purchases must meet the minimum energy efficiency requirements outlined in the following chart when acquiring residential electric resistance water heaters of the types and sizes described below.
Heat pump water heaters are the most efficient type of electric water heater available, and are used as the best available option within the table below. Whenever possible, federal purchasers should acquire heat pump water heaters.
The efficiency requirements below should be used to procure water heaters when a heat pump water heater is not appropriate for the space or application.
|Energy Efficiency Requirements for Federal Purchasesa|
|Storage Volume||Energy Factorb||Annual Energy Usec|
|55 gallons or less||0.93 or greater||4,721 kWh or less|
|56 gallons or more||0.92 or greater||4,773 kWh or less|
|a Requirements as of August 3, 2011.
b Energy factor is an efficiency ratio of the energy supplied in heated water divided by the energy input to the water heater.
c Based on U.S. Department of Energy (DOE) test procedure (10 CFR 430, Subpart B, Appendix E).
Specify or select residential electric resistance water heaters that meet or exceed the energy efficiency requirements outlined above. Information on energy factors can be found in the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) Directory of Certified Product Performance. Annual energy use is listed on the yellow EnergyGuide label required on these products.
These requirements apply to all forms of procurement, including construction guide specifications and project specifications; renovation, repair, maintenance, and energy service contracts; lease agreements; acquisitions made using purchase cards; and solicitations for offers. Energy efficiency requirements should be included in both the evaluation criteria of solicitations and the evaluations of solicitation responses.
Federal Acquisition Regulation (FAR) Part 23.206 requires federal agencies to insert the clause at FAR section 52.223-15 in solicitations and contracts that deliver, acquire, furnish, or specify energy-consuming products. FEMP recommends that agencies incorporate efficiency requirements into both the technical specification and evaluation sections of solicitations. Agencies may claim an exception to these requirements through a written finding that no ENERGY STAR-qualified or FEMP-designated product is available to meet the functional requirements, or that no such product is life cycle cost effective for the specific application. Additional information on federal requirements is available.
Buyer Tips: How to Choose Efficient Products
Heat pump water heaters are the most efficient electric-storage-type water heaters available, using half the energy or less of electric resistance models. The table below compares the energy use of electric resistance models with an ENERGY STAR-qualified heat pump water heater. All three are 50-gallon capacity models producing 64 gallons of hot water per day at 135°F.
|Energy Use Comparison|
|Performance||Base Model||Required (federal acquisitions must meet or exceed this level)||ENERGY STAR-qualified heat pump water heater|
|Annual Energy Use||4,879 kWh||4,721 kWh||2,195 kWh|
|10 Year Energy Use||48,790 kWh||47,210 kWh||21,950 kWh|
|10 Year Energy Savings||–||1,580 kWh||26,840 kWh|
Energy savings for the heat pump water heater is almost 17 times greater than electric resistance models meeting this specification. Heat pump water heaters are the same size and use the same connections as stand models, offering a drop-in replacement for most electric water heaters. In addition, heat pump water heaters are equipped with advanced controls that allow users to easily switch modes, change temperatures, and shut down during vacations. These features can provide additional energy and cost savings.
Whenever possible, federal purchasers should acquire heat pump water heaters. Check manufacturer installation requirements to make sure a heat pump water heater can be installed at your specific location. Electric resistance, storage-type water heaters should only be used when heat pump water heaters do not have adequate space or the required clearances.
Storage-type water heaters are the most commonly used models, but also the least efficient. They have higher standby losses because they keep tanks full of heated water at all times and are typically located away from points of use. Where hot water use is low (e.g., kitchenettes and office restrooms), installing tankless water heaters can save additional energy. These units are also called demand-type or instantaneous water heaters, and only heat water as needed, resulting in low standby losses and energy factors of around 0.99. In addition, their compact size allows them to be located near the point of use, further reducing heat loss through piping.
Water heaters must be sized properly. Oversized products cost more to buy and use more energy due to excessive cycling and higher standby power losses. A water heater should be selected based on its FHR, not storage capacity.
Determining Cost Effectiveness
An efficient product is cost effective when the energy cost savings over its functional lifetime exceed any initial incremental cost above a base model (i.e., energy cost savings is greater than additional costs at time of purchase). Federal purchasers may assume that ENERGY STAR-qualified and products meeting FEMP-designated efficiency requirements are life cycle cost effective. However, users wishing to determine cost effectiveness for their application may do so using the below cost effectiveness example or the water heater energy and cost calculator.
Products meeting FEMP-designated efficiency requirements or ENERGY STAR performance specifications may not be life cycle cost effective in certain low-use applications, such as when a device is being purchased for backup purposes and will remain in off mode for most of its useful life. For most other average or high-use applications, purchasers will find that energy-efficient products have the lowest life cycle cost.
The table below provides energy and cost savings for 50- and 80-gallon capacity electric resistance water heaters. In both, the efficiency of the base model is the minimum allowed by DOE appliance standards. The required model meets federal requirements. The best available model is from the AHRI directory.
|Energy and Cost Savings Example (50-gallon Capacity)|
|Annual Energy Use||4,879 kWh||4,721 kWh||4,622 kWh|
|Annual Energy Cost||$440||$425||$415|
|Lifetime Energy Cost||$4,640||$4,490||$4,396|
|Lifetime Energy Cost Savings||–||$150||$244|
The required 50-gallon model is cost effective if priced no more than $150 above the base model. The best available 50-gallon model is cost effective if priced no more than $244 above the base model.
|Energy and Cost Savings Example (80-gallon Capacity)|
|Annual Energy Use||5,106 kWh||4,773 kWh||4,622 kWh|
|Annual Energy Cost||$460||$430||$415|
|Lifetime Energy Cost||$4,856||$4,540||$4,396|
|Lifetime Energy Cost Savings||–||$316||$460|
The required 80-gallon model is cost effective if priced no more than $316 above the base model. The best available 80-gallon model is cost effective if priced no more than $460 above the base model.
Annual energy use is based on DOE test procedure (10 CFR 430). The assumed rate of electricity is $0.09 per kWh, the average at U.S. federal facilities. Lifetime energy cost is the sum of the discounted valued of annual energy cost with an assumed water heater life of 13 years. Future electricity price trends and a 3% discount rate are from the Price Indices and Discount Factors for Life Cycle Cost Analysis.
User Tips: How to Use Products More Efficiently
For most residential applications, set the temperature at 120°F. Under certain conditions, Legionella pneumophila, the bacteria known to cause Legionnaires Disease, can grow in water heaters. The Unified Facilities Criteria (UFC), the master specification used by the U.S. Department of Defense (DOD), requires users to "set service water heater (SWH) storage temperature set point for not less than 140ºF (60°C) to limit the potential for growth of Legionella pneumophila." At this water temperature, bacteria can survive for less than a minute. However, it also poses a risk for scalding, especially for young children and the elderly. Because of this, the UFC requires a "balanced-pressure-type tempering valve" to be installed downstream of the service water heater storage tank to provide anti-scalding protection. For residential applications, set the temperature on this device, also known as a mixing valve, to 120°F.
Turning water heaters down or off during unoccupied periods also reduces energy use and costs, as do timers or other load control devices in buildings with time-of-use rates or demand charges.
Updated January 2014.