A cooling system should make a hot day easier to manage, not create an unwelcome surprise on your energy bill. Knowing how to lower cooling bills starts with understanding where electricity is being wasted: through an inefficient setting, a poorly maintained unit, heat entering the building, or an air conditioning system that is no longer right for the space.
For homeowners, landlords and business owners, the aim is not to switch the air conditioning off and put up with uncomfortable rooms. It is to achieve dependable comfort with less wasted energy. The following practical steps can make a meaningful difference, particularly during prolonged warm spells.
Set a realistic temperature
Turning the thermostat down to its lowest setting will not cool a room faster. It simply tells the system to run for longer, which can increase running costs and place more strain on the equipment.
As a general guide, a setting around 23-25°C is comfortable for many homes and workplaces in summer. The right temperature depends on the room, how much sunlight it receives, the number of people using it and personal preference. A server room, busy shop or south-facing office may have different requirements from a bedroom or lounge.
Try increasing your usual setting by one degree and see whether comfort changes. Even a small adjustment can reduce the amount of time the system needs to run. Avoid large temperature swings too. Bringing a building back from a very high indoor temperature usually costs more than maintaining a sensible, steady setting.
Use timers and controls properly
Air conditioning is most efficient when it cools occupied spaces at the right time. Running a system all day in an empty property, or overnight in an unused office, is an avoidable expense.
Use timers, schedules or smart controls to start cooling shortly before people arrive and reduce output when rooms are vacant. At home, this may mean cooling bedrooms before bedtime rather than leaving the unit on from mid-afternoon. In a workplace, separate zones can prevent one thermostat from controlling areas with very different heat loads.
Do not set schedules too tightly during a heatwave. Buildings retain heat, particularly those with large windows or flat roofs, and the system may need a little time to bring the temperature down. A qualified engineer can help configure controls around how your property is actually used, rather than relying on a one-size-fits-all programme.
Keep filters, coils and drains clean
A blocked filter restricts airflow. When airflow falls, the unit must work harder to deliver the same cooling, using more energy and increasing the risk of faults. Dirty filters can also affect indoor air quality, allowing dust and other airborne particles to circulate around the room.
Check washable or replaceable filters in line with the manufacturer’s guidance, and more often in properties with pets, high footfall or dusty working environments. A filter may look harmlessly grey but still be restricting performance.
Professional servicing goes further than a filter check. An engineer can inspect the indoor and outdoor coils, condensate drain, fan operation, electrical connections and refrigerant performance. These are the details that help a system run safely, efficiently and reliably when it is needed most. Regular servicing is usually less disruptive and less costly than dealing with a breakdown in the middle of summer.
Stop heat before it reaches the room
Air conditioning has to remove the heat that enters your building. Reducing that heat gain is one of the most effective ways to lower cooling bills, especially in sun-facing rooms.
Close blinds, curtains or shutters before direct sunlight reaches the glass. Light-coloured linings and reflective window coverings can help reduce solar heat, while external shading is often even more effective where suitable. Keep windows and external doors closed while the air conditioning is operating. It is easy to overlook a door left open in a shop, reception area or kitchen, but it can make the system run continuously.
Look for smaller sources of heat as well. Computers, printers, lighting, cooking equipment and refrigeration can all raise indoor temperatures. Switching off unused equipment and choosing efficient lighting can reduce the cooling demand, particularly in compact offices and commercial premises.
Use fans to support, not replace, cooling
Ceiling fans and portable fans do not lower the room temperature, but they improve air movement and make occupants feel cooler. This means you may be able to raise the air conditioning set point slightly while maintaining comfort.
Fans work best when people are in the room. There is little benefit in leaving them running in an empty space, as their motors produce a small amount of heat and consume electricity. In bedrooms and living areas, a quiet fan used alongside a moderate air conditioning setting can be a practical way to reduce running costs.
Check whether your system is the right size
An air conditioning unit that is too small may run almost constantly on hot days without achieving the desired temperature. One that is too large can cool a room quickly but cycle on and off too often, reducing efficiency and sometimes leaving the air feeling clammy.
Correct sizing is about more than floor area. A proper assessment considers ceiling height, insulation, glazing, orientation, occupancy, appliances and how the rooms are used. This is especially important when converting a loft, extending a property, changing an office layout or fitting out a retail unit.
Older equipment can also become less economical to run, even when it still appears to work. Modern inverter-driven systems adjust their output to match demand rather than repeatedly switching at full power. An upgrade is not always the right answer, particularly if a repair and service will restore performance. However, where a system is ageing, unreliable or poorly matched to the space, replacement can offer lower energy use, quieter operation and more consistent year-round comfort through heat pump capability.
Protect the outdoor unit
The outdoor unit needs clear airflow to release heat effectively. Leaves, soil, garden furniture, stored stock or overgrown planting can restrict it, forcing the system to work harder and potentially increasing electricity use.
Keep the area around the unit clear and avoid placing items directly against it. Some shade can help in very sunny locations, but do not build an enclosure or cover that blocks ventilation. The unit must remain accessible for safe inspection and maintenance.
If you notice unusual noise, reduced cooling, water leaks indoors, ice forming on pipework or a sharp rise in energy use, arrange a professional check rather than continuing to run the system. Small faults can become larger and more expensive when left untreated.
Choose habits that reduce demand
The most economical cooling is the cooling you do not need. Opening windows early in the morning, when outdoor air is cooler, can help remove overnight heat before closing the property up for the day. Once temperatures rise outside, close windows and use shading to retain the cooler indoor air.
For businesses, simple staff guidance can make a real difference. Agree who controls thermostats, remind teams to close doors, and avoid competing heating and cooling in different zones. For landlords, providing clear operating instructions helps tenants use the system efficiently and reduces avoidable call-outs.
It is also worth reviewing energy bills against previous periods. A gradual rise may reflect hotter weather, but it can also point to a clogged filter, a control issue or declining system performance. Addressing the cause early protects both comfort and equipment lifespan.
When professional advice is worthwhile
If your system is running for long periods, failing to cool evenly or costing noticeably more than before, a service visit can provide clarity. A qualified engineer can assess performance, identify maintenance needs and advise whether adjustments, repairs or a more efficient replacement would offer the best value.
Walsh Air Conditioning provides tailored support for homes and businesses, with qualified engineers, transparent fixed-price quotations and ongoing care options designed to keep climate-control systems dependable throughout the year. The right advice should leave you with a clear picture of the work required, the likely costs and the benefits you can expect.
Lower bills are often the result of several small improvements rather than one dramatic change. Start with the thermostat, filters and shading, then arrange a professional assessment if performance still does not feel right. A well-maintained, correctly controlled system should deliver cool, comfortable rooms without working harder than it needs to.