There are several technology upgrades that can reduce cooling costs by either improving the efficiency of the cooling system or reducing the amount of cooling a home requires. These upgrades range from replacing the cooling system itself to improving the building envelope, air distribution, and temperature controls.
Replacing an older or inefficient cooling system with a high-efficiency system can significantly reduce the amount of energy required to cool a home. When purchasing a new cooling system, look for heat pumps with strong energy-efficiency ratings and certifications used in your region. If you are in the US, look for an Energy Star certified heat pump.
In the US, central air conditioners and heat pumps are commonly rated using the Seasonal Energy Efficiency Ratio 2 (SEER2). The higher the SEER2 rating, the more efficiently the system provides cooling. Look for heat pumps with a SEER2 rating of at least 15.2, which is the current minimum cooling-efficiency requirement for Energy Star-certified residential air-source heat pumps. Higher-efficiency models can have SEER2 ratings above 20.
Proper system sizing is also important. A cooling system’s capacity is commonly measured in British thermal units per hour (Btu/h) or tons (one ton of cooling capacity equals to 12,000 Btu/h). For example, if a home requires 30,000 Btu/h of cooling, a 5-ton (60,000 Btu/h) system would be oversized. Oversized systems can cycle too frequently, reducing efficiency and humidity control, while undersized systems may struggle to maintain comfortable temperatures.
The appropriate system size depends on factors such as the home's size, climate, insulation, air leakage, windows, orientation, and occupancy. An HVAC professional should calculate the home's heating and cooling needs using an industry-standard cooling load calculation before selecting the size of new equipment.
Fans can reduce the need for air conditioning by making occupants feel cooler without lowering the temperature of the room. Ceiling and portable fans increase air movement across the skin, allowing occupants to remain comfortable at higher indoor temperatures.
Because fans typically use much less energy than air-conditioning systems, using a fan while raising the thermostat setpoint can reduce cooling energy consumption while maintaining comfort. Because fans cool people rather than rooms, they should be turned off when a room is unoccupied.
Improving the home’s building envelope reduces the amount of outdoor heat that enters the home. Adding insulation to roofs, attics, walls, and floors slows heat transfer between the outdoors and the conditioned interior. Air sealing reduces the amount of warm, humid outdoor air that enters through gaps and cracks in the building envelope.
Windows can also be an important source of heat gain. Energy-efficient windows can reduce heat transfer and solar heat gain, while exterior shading, window films, and appropriate window coverings can reduce the amount of solar energy entering through windows.
By reducing indoor heat gain, building envelope improvements decrease the amount of heat the cooling system must remove to maintain a comfortable indoor temperature.
Homes with central cooling systems can lose energy through leaky or poorly insulated ductwork. Sealing duct leaks and insulating ducts, particularly those located in unconditioned spaces such as attics, garages, and crawl spaces, can reduce these losses and help more of the conditioned air reach the intended rooms.
Zoning can further reduce cooling demand by dividing a home into areas that can be controlled independently. For example, a two-story home might create a separate zone controlled by its own thermostat for each floor, allowing the cooling system to maintain different temperatures upstairs and downstairs. This can allow occupants to reduce cooling in areas that are unoccupied or have different cooling needs.
Ductless mini-split systems can provide similar zoning benefits because individual indoor units can independently control the temperature of different rooms or areas without using central ductwork.