Understand High Efficiency Water Heater Technologies

High Efficiency Water Heaters Provide Hot Water for Less Heating water accounts for approximately 15% of a home’s energy use. High efficiency water heaters use 10 to 50% less energy than standard models, saving homeowners money on their bills. Actual energy savings from high-efficiency water heaters depend on family size, heater location, and the size […]

U.S. Geothermal Power at Present

Part 5 of Geothermal Energy Under Our Feet. Today’s U.S. geothermal industry is a $2-billion per-year enterprise involving over 2800 MW of electricity generation capacity, about 620 MW of thermal energy capacity in direct-use applications such as indoor heating, greenhouses, food drying, and aquaculture, and over 7,300 MW of thermal energy capacity from geothermal heat […]

Geothermal Resource Descriptions

Part 4 of Geothermal Energy Under Our Feet. Hydrothermal A hydrothermal system is defined as a subterranean geothermal reservoir that transfers heat energy upward by vertical circulation of fluids driven by differences in fluid density that correspond to differences in temperature (see Figure 2). Hydrothermal systems can be classified into two types—vapor-dominated and hot water— […]

United States Geothermal Resources

Part 2 of Geothermal Energy Under Our Feet. The United States possesses vast underground stores of heat whose full potential has yet to be realized. The Earth’s interior reaches temperatures greater than 4,000°C (>7,200°F), and this geothermal energy flows continuously to the surface. The energy content of domestic geothermal resources to a depth of 3 […]

Under Our Feet: Geothermal Energy

Part 1 of Geothermal Energy Under Our Feet. The Earth houses a vast energy supply in the form of geothermal resources. Domestic resources are equivalent to a 30,000-year energy supply at our current rate for the United States! In fact, geothermal energy is used in all 50 U.S. states today. But geothermal energy has not […]

Geothermal Energy: The Heat Pump Solution

Part 5 of Geothermal Energy: Power from the Depths of the Earth. The geothermal heat pump doesn’t create electricity—but it greatly reduces consumption of it. If you would like to reduce the cost of heating and cooling your home, you might want to consider installing a geothermal heat pump, an economical and energy-efficient technology for […]

Using Geothermal Energy Directly

Part 4 of Geothermal Energy: Power from the Depths of the Earth. If you’ve ever soaked in water from a natural hot spring, you’re one of the millions of people around the world who has enjoyed the direct use of geothermal energy. And while this naturally occurring hot water may be the perfect tonic for […]

Geothermal Heat Pumps Make Sense for Homeowners

Geothermal heat pumps are one of the most efficient ways to heat and cool a home and provide hot water. More and more homeowners are discovering the benefits of these systems, which tap the relatively constant temperature of the Earth a few feet underground, for both new homes and retrofits in existing houses. Geothermal heat […]

Benefits of a Geothermal Heat Pump System

Part 3 of Geothermal Heat Pumps. GHP systems have the lowest carbon dioxide emissions of all the heating and cooling technologies. Low Energy Use The biggest benefit of GHPs is that they use 25-50% less electricity than conventional heating or cooling systems. This translates into a GHP using one unit of electricity to move three units […]

What Is a Geothermal Heat Pump & How does it work?

Part 2 of Geothermal Heat Pumps. Geothermal heat pumps can reduce energy consumption—and corresponding air pollution emissions—up to 44% compared to air source heat pumps and up to 72% compared to electric resistance heating with standard air-conditioning equipment. (Source: EPA, 1993) Geothermal heat pumps are viable nationwide. They use the Earth as a heat sink […]

Overview: Geothermal Heat Pumps

Part 1 of Geothermal Heat Pumps. If you’re planning to build a new house, office building, or school, or replace your heating and cooling system, you may want to consider a geothermal heat pump (GHP) system. GHP systems are also known as GeoExchange, ground-source, or water-source heat pumps (as opposed to air-source heat pumps). Regardless […]

Energy-Efficient Air Conditioning

Are you considering buying a new air conditioner? Or, are you dissatisfied with the operation of your current air condi- tioner? Are you unsure whether to fix or replace it? Are you concerned about high summer utility bills? If you answered yes to any of these questions, this publication can help. With it, you can […]

Resources: Air-Source Heat Pumps

Part 8 of Air-Source Heat Pumps. The following are sources of additional information on heat pumps. This list is not exhaustive, nor does the mention of any resource constitute a recommendation or endorsement. Ask an Energy Expert DOE’s Energy Efficiency and Renewable Energy Clearinghouse (EREC) P.O. Box 3048 Merrifield, VA 22116 1-800-DOE-EREC (363-3732) Online submittal form. Energy […]

Maintaining and Servicing

Part 7 of Air-Source Heat Pumps. Heat-pump performance will deteriorate without regular maintenance and service. The difference between the energy consumption of a well-maintained heat pump and a severely neglected one ranges from 10 to 25 percent. Regular Maintenance Either the homeowner or service technician can perform the following routine maintenance tasks: Clean or replace […]

Operating a heat pump

Part 6 of Air-Source Heat Pumps. Like combustion heating systems, you control heat pumps using thermostats. If you leave and return at regular times everyday, you’ll save money by using automatic thermostats, which minimize energy use during the times the home is unoccupied. However, choosing an automatic thermostat’s reactivation time requires considering the duration of […]

Improving Performance

Part 5 of Air-Source Heat Pumps. Poor installation, duct losses, and inadequate maintenance are more of a problem for heat pumps than for combustion furnaces. A growing body of evidence suggests that most heat pumps have significant installation or service problems that reduce performance and efficiency. According to a report on research funded by Energy […]

Installing a New Heat Pump

Part 4 of Air-Source Heat Pumps. A heat pump’s performance and energy efficiency not only depend on the selection and planning of the equipment but also on careful installation. Consumers and home builders alike tend to accept the lowest bid for heating and air-conditioning work. This unfortunate choice can often leave a system lacking 10 […]

Selecting a Heat Pump

Part 3 of Air-Source Heat Pumps. When selecting an air-source heat pump, consider the following three characteristics carefully: the energy efficiency rating, sizing, and the system’s components. Energy efficiency rating In the United States, we rate a heat pump’s energy efficiency by how many British thermal units (Btu) of heat it moves for each watt-hour […]

Types of Air-Source Heat Pumps

Part 2 of Air-Source Heat Pumps. A split-system heat pump heating cycle You can use a central heat pump to heat and cool a whole house. Most central heat pumps are split-systems—that is, they each have one coil indoors and one outdoors (see Fig. 1 below). Supply and return ducts connect to a central fan, […]

Air-Source Heat Pumps

Part 1 of Air-Source Heat Pumps. There are two common types of heat pumps: air-source heat pumps and geothermal heat pumps (GHPs). Either one can keep your home warm in the winter and cool in the summer. An air-source heat pump pulls its heat indoors from the outdoor air in the winter and from the […]

Heating and Cooling Systems

Part 4 of Elements of an Energy-Efficient House. Specifying the correct sizes for heating and cooling systems in airtight, energy-efficient homes can be tricky. Rule-of-thumb sizing is often inaccurate, resulting in wasteful operation. Conscientious builders and heating, ventilation, and air-conditioning contractors size heating and cooling equipment based on careful consideration of the thermal envelope characteristics. […]

Heat Pump Water Heaters

Part 4 of Selecting a New Water Heater. Heat pump water heaters use electricity to move heat from one place to another instead of generating heat directly. To heat water for homes, heat pump water heaters work like refrigerators in reverse. Heat pump water heaters can be purchased as integral units with built-in water storage […]

Heating and Cooling

Part 4 of Ways to Save Money on Energy at Home. Heating and cooling your home uses more energy and drains more energy dollars than any other system in your home. Typically, 44% of your utility bill goes for heating and cooling. What’s more, heating and cooling systems in the United States together emit over a […]

Energy-Efficient Appliances

Part 5 of A Guide to Making Energy-Smart Purchases. The energy efficiency of similar appliances can vary significantly. It is usually more cost effective to purchase appliances with high efficiencies. Determining and comparing the energy efficiency of different models is usually easy, because federal regulations require many types of appliances to display EnergyGuide labels. A […]