Reducing your air conditioning energy bills
Once air conditioning is installed, the biggest factor in your ongoing bill isn't the unit's rated efficiency but how it's actually used day to day. We're asked regularly by both homeowners and business clients how to bring running costs down without replacing perfectly good equipment, and the honest answer is that a handful of habits and a bit of routine maintenance usually make far more difference than people expect.
This guide covers the practical changes worth making first, before you consider anything more drastic like replacing units or renegotiating your energy tariff.
Get the target temperature right
Every degree you set below around 22 to 24 degrees Celsius in cooling mode increases running cost noticeably, because the unit has to work harder to maintain a bigger gap between indoor and outdoor temperature. A commonly used guideline is to set cooling around 6 to 8 degrees below the outdoor temperature rather than chasing an arbitrarily low number, which keeps the room comfortable without unnecessary compressor strain.
The same principle applies in reverse for heating mode in cooler months. Setting heating a few degrees lower than you might with a boiler, and allowing the room to settle there, avoids the unit constantly overshooting and cycling.
Use zoning and scheduling properly
If you have multiple indoor units on a multi-split or ducted system, only running the zones actually in use is one of the simplest savings available. Cooling an empty meeting room or spare bedroom all day for no reason is a common and entirely avoidable cost in both homes and offices.
Most modern controllers, whether wall-mounted, app-based or building management systems in commercial premises, allow scheduling so units switch off overnight or outside working hours automatically. Setting this up once removes the reliance on someone remembering to turn units off manually, which in practice rarely happens consistently.
Don't fight the building
Air conditioning has to work far harder in a room with direct afternoon sun through unshaded glazing, or with doors and windows left open while it's running. Closing blinds during the hottest part of the day, keeping external doors shut, and sealing obvious draughts around older windows all reduce the load the system has to overcome.
In commercial premises this is particularly relevant for shop fronts and restaurants where doors are propped open for customer flow. It's worth weighing the comfort and running cost impact against the benefit of an open entrance, especially during peak summer weeks.
Keep maintenance up to date
- Dirty filters restrict airflow and force the unit to run longer to achieve the same cooling, increasing electricity use noticeably over a season.
- A dirty outdoor coil struggling to reject heat makes the whole system less efficient, even if the indoor unit looks clean.
- Low refrigerant charge from a slow leak reduces capacity and efficiency long before the unit stops cooling altogether, so it can go unnoticed for months.
- An annual service catches most of these issues before they show up as a higher bill or a breakdown.
Consider your electricity tariff and time of use
If you're on a time-of-use tariff, or considering one, shifting heavier cooling or heating demand away from peak pricing periods where practical can reduce cost even with identical total energy use. This matters more for commercial premises with predictable operating hours than for homes, but it's worth checking your tariff structure against how your system actually runs through the day.
When it's worth a proper review
If you've tackled settings, zoning and maintenance and bills are still higher than expected, it's usually worth having an engineer look at whether the system was sized and commissioned correctly in the first place, since an oversized or badly set up unit will never run efficiently no matter how carefully it's used. Get in touch for a free quote and we can review your current setup and recommend where the real savings are, rather than guessing.
FAQs
Common questions
What temperature should I set air conditioning to for the lowest running cost?
Around 6 to 8 degrees below outdoor temperature for cooling is a sensible guideline, rather than a fixed number, since it limits how hard the unit has to work.
Does turning air conditioning off and on repeatedly save energy?
Not usually. Letting the unit run on a schedule or modulate via its own controls is generally more efficient than manual on-off cycling, especially with inverter units.
How much does a dirty filter actually affect running costs?
It varies with use, but restricted airflow makes the unit run longer for the same result, and it's one of the most common avoidable causes of higher bills we see.
Is it worth closing internal doors while air conditioning is running?
Yes, keeping the cooled or heated space smaller and more contained reduces the volume the unit has to condition, which helps efficiency.
Can a maintenance contract help reduce bills?
Yes, regular servicing keeps filters, coils and refrigerant charge in good order, which are the main maintenance-related causes of rising running costs.
Will replacing an old unit with a new one always cut my bills?
Often, if the old unit is genuinely inefficient or oversized, but it's worth checking usage habits and maintenance first, since those changes are free and sometimes deliver most of the saving.
Keep reading
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Air conditioning lifespan and replacement planning
Knowing roughly when a system will need replacing lets you budget properly instead of facing an unplanned failure and an emergency decision.
System & comparison guides
Heating with air conditioning in winter
Most modern air conditioning units heat as well as they cool, and for many rooms that heat is cheaper to run than it looks.
Fault & symptom guides
Air conditioning troubleshooting checklist
A handful of simple checks can rule out the easy causes before you book an engineer, and a clear symptom guide tells you roughly what you're dealing with.
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