Energy-saving HVAC systems
Climate, costs, and technology matter in choosing among the optionsBy Thomas Kirk
Did you know that more than half of what you're spending on energy bills goes to heating and cooling your home? You can turn this necessary expense into savings, however, by selecting the appropriate heating, ventilation and air conditioning (HVAC) system for your needs.
Modern systems featuring ductless, air-source, or ground-source technologies are just as effective as more traditional systems, but are much more energy efficient.
If you are conditioning smaller areas in retrofits, home additions, or in new construction, a ductless heat pump (DHP) may be right for you. The DHP uses an estimated 50 to 60 percent less energy than electric resistance heating systems and may exceed the efficiency of ducted heat pump systems by more than 25 percent. They're composed of an outside compressor, indoor air handling units, refrigerant lines, and a controller (either an in-home display or wireless remote).
A 1¼ ton DHP system — an average size for heating and cooling a single-zone home — could cost about $4,000 to install. Pricing varies based on brand and installation needs. But despite the benefits, some consumers may not like having their heating system and equipment visible. When DHPs are installed, units are placed indoors, mounted on a wall or ceiling.
Ducted electric air-source heat pumps (ASHPs) provide year-round space-conditioning and can both heat and cool a home. They use a single piece of equipment — allowing for a lower cost in most cases — and provide heat cheaper than electric resistance heating. These systems work by transferring energy between the air outside and either the air or water inside a building. This principle of moving energy, not creating heat, is what allows ASHPs to be more efficient than electric resistance heating.
When choosing an ASHP, consider your local climate and heating needs. Most air source heat pumps are best suited to relatively warm climates, such as the southeastern U.S. When temperatures are low in such regions, a heat pump's efficiency falls dramatically.
Choosing the right-sized system is also important. If a heat pump is too small, it can't provide sufficient cooling, and an oversized one can be costly and require ductwork and other equipment to operate, adding expense. Newer systems are proving effective in northern regions, especially when combined with a backup fuel source such as natural gas.
Ground source heat pumps (GSHP), also called geothermal heat pumps or geoexchange systems, are electrically powered devices that use consistent year-round temperatures found underground to regulate indoor air temperature. GSHP systems are composed of one or more underground loops that act as heat exchangers. They are connected to a heat pump unit that is then connected to a home's heating and air conditioning system. In the summer, the loops transfer heat from the home into the ground, or in some cases, water. In the winter, the process is reversed. In most climates they are much more efficient than air source heat pumps and other standard HVAC equipment.
Savings vary depending on climate. The U.S. Department of Energy estimates that most homeowners will see a return on their investment in a GSHP system in two to 10 years through lower energy bills. A desuperheater or hot water generator can be added, eliminating the need to heat water with gas or more electricity.
Electric co-op and government deals
Think carefully about whether a high-efficiency system will save you money in the long run and if it meets your HVAC needs. Prices vary significantly by manufacturer, region, dealer and time of year. As you comparison shop, be sure to get local or regional price quotes. Some of the best savings and deals can come from your local electric cooperative and from government programs offering rebates, tax incentives, or interest-free loans.