Why does air conditioning energy efficiency matter?
Air conditioning is one of the largest energy users in a Queensland home over summer. Improving its efficiency lowers your power bills and reduces the emissions linked to the electricity you use, without giving up comfort. Many of the biggest gains cost little or nothing.
Energy efficiency is more than a buzzword. When it comes to air conditioning, it means getting the same comfort for less electricity. This guide covers the factors that drive your system’s energy use, practical ways to improve efficiency, and the technologies that make the biggest difference.
What affects how much energy your air conditioner uses?
Five things drive energy use: whether the system is the right size, how well the house is insulated and sealed, the temperature you set, how well the system is maintained, and outdoor conditions such as heat, humidity and direct sun on the house and outdoor unit.
1. System size
An oversized system cycles on and off frequently, which wastes energy and removes less humidity. An undersized system runs flat out and still struggles on hot days. A room-by-room heat load calculation at the quote stage gets the size right.
2. Insulation and air sealing
Poor ceiling and wall insulation, and gaps around doors, windows and downlights, let heat in, so the system works harder to keep rooms comfortable. Improving insulation and sealing reduces the load on every system.
3. Temperature settings
Setting the temperature too low uses more energy without cooling the room any faster. Raising the cooling set point by a degree or two, to 25–27°C, reduces running costs noticeably.
4. Maintenance and cleaning
Dirty filters, clogged coils and blocked vents restrict airflow and reduce efficiency. Regular cleaning and servicing keep the system running as it was designed to.
5. Outdoor conditions
Extreme heat and humidity increase the load. Shading the outdoor unit (without blocking its airflow), shading west-facing windows, and correct sizing and insulation all help reduce the effect.
How can you improve your air conditioner’s energy efficiency?
Service the system regularly, upgrade old equipment to a high-star-rated inverter model, improve insulation and sealing, use timers or smart controls, use natural ventilation and shading, and cool only the rooms you use with zoning or separate split systems.
1. Schedule regular maintenance
A service should include cleaning coils, cleaning or replacing filters, checking refrigerant and electrical connections, and checking fans and drains. It keeps the system at its rated performance and catches faults early. See air conditioning maintenance.
2. Upgrade to high-efficiency equipment
If your system is old, consider replacing it with a modern inverter model. Ignore US terms such as Energy Star and SEER; in Australia, compare the star ratings on the Zoned Energy Rating Label, which shows separate cooling and heating stars and estimated yearly energy use for hot, average and cold zones. More stars means lower running costs. See air conditioning replacements.
3. Improve insulation and air sealing
Top up ceiling insulation, seal gaps around doors and windows, and make sure ducts in the roof space are sealed and insulated. On new ducted installs we offer an R1.5 ducting upgrade. Read about proper air duct design and maintenance.
4. Use programmable or smart controls
Timers, schedules and app control let you cool the house for when you are home and ease off when you are not or are asleep. See the benefits of smart thermostats.
5. Use natural ventilation and shading
Open up the house to sea breezes on mild days and evenings and use ceiling fans. On hot days, close blinds, curtains or external shades on sunny windows, especially to the west, to block heat before it gets in.
6. Consider zoning and split systems
Zoning on a ducted system, or separate split systems in the rooms you use most, cool only the spaces that need it, rather than the whole house. That avoids paying to cool empty rooms.
Which technologies save the most energy?
Inverter (variable-speed) compressors, smart controls and zoning, reverse-cycle heat pump technology and, in some homes, energy recovery ventilation all reduce energy use. Pairing your system with rooftop solar also cuts the cost of running it during the day.
1. Variable-speed (inverter) compressors
Inverter compressors adjust their speed to match demand, holding temperatures steadily and using less power once the room is comfortable. They are standard in current systems from the major brands.
2. Smart controls
Smart controllers add remote access, schedules, zone control and usage information, which make efficient habits easy. For ducted systems, AirTouch 5 adds temperature control for each zone.
3. Heat pump (reverse-cycle) technology
Reverse-cycle air conditioners are heat pumps. They move heat rather than generate it, delivering efficient cooling in summer and efficient heating in winter from the same system.
4. Energy recovery ventilation (ERV)
ERV systems bring in fresh air while exchanging heat and moisture with the outgoing air, so you get ventilation without throwing away as much of the energy you used to cool the house. They are more common in commercial buildings and very airtight homes.
What is the bottom line?
Maximising your air conditioner’s efficiency is good for your budget and the environment. Get the size right, keep heat out, use sensible settings and zoning, maintain the system, and choose efficient equipment when you upgrade. If you have solar, run cooling while the sun is up. For help with any of these, get in touch.