Is Your HVAC System Wasting Energy?

by Sheddy Bloggs | Aug 18, 2025 | Heating and Cooling, Weather & Climate | 0 comments

Heating and cooling account for a big chunk of your energy bill, especially in Australia’s crazy climate. Whether you’re running your air conditioner all summer or keeping warm during winter, your HVAC system is a big part of home comfort.

But what if it’s doing more harm than good to your wallet?

If your system is old, not maintained, or just not suited to your home anymore, it might be using more power than it needs to. Let’s break down the common signs of energy waste, what causes them, and how to fix or avoid them.

Signs Your HVAC System Might Be Wasting Energy

You don’t need to be a tech to notice something’s not quite right. Here are a few red flags to watch for:

Your energy bills have gone up
If you’ve noticed a steady increase in your power bill without any major changes in how you use your heating or cooling, your HVAC system is probably running inefficiently.
Some rooms are colder or warmer than others
Uneven temperatures around the house mean your system isn’t distributing air properly. This could be due to blocked vents, duct leaks, or poor system design.
Your system is always on
If your heating or cooling is always on, struggling to reach or maintain the set temperature, it might be too small for your home or losing efficiency with age.
The unit is making weird noises
Rattles, hisses, or buzzing sounds can mean parts are wearing out, which can impact energy use.
Your filters are dirty all the time
If you’re changing filters more than usual or they’re clogging quickly, the system is pulling in more dust than it should, making it work harder.

Common Causes of HVAC Energy Waste

Even new systems can waste energy if they’re not set up or maintained properly. Here’s what to look out for:

1. Poor Maintenance

HVAC systems need regular attention. Dirty filters, clogged coils and neglected components make the unit work harder. And that means more electricity for the same result, or worse performance.

What to do:
Check and clean your filters monthly, especially in high-use seasons. “Schedule professional servicing: a comprehensive servicing by a certified technician should be scheduled at least once a year. This professional can thoroughly check the refrigerant levels, inspect for leaks, and make sure all electrical components are working correctly,” recommends afterhoursairconditioning.com.au. They’ll also inspect ductwork and tune up other parts to keep your system running at its best.

2. Leaky Ducts

Leaky ducts are a silent energy killer. Warm or cool air escapes into walls or the roof space before it even reaches the rooms you’re trying to heat or cool. This is especially common in older homes.

What to do:
A duct pressure test can help identify leaks. Sealing and insulating ducts can greatly reduce energy loss, especially in homes with ducted reverse-cycle air conditioning.

3. Outdated System

HVAC technology has come a long way. Systems that are more than 10 or 15 years old simply aren’t as efficient as newer models. They may also rely on older refrigerants, which are not only less eco-friendly but also more expensive to replace.

What to do:
If your unit is nearing the end of its life or needs frequent repairs, upgrading to an energy-efficient model might save you money in the long run. Look for systems with a high star rating under Australia’s Energy Rating Label program.

4. Poorly Sized System

A unit that’s too small for your home will run constantly without ever really getting the job done. A unit that’s too big will cycle on and off frequently, which can wear it out faster and waste energy in short bursts.

What to do:
A professional load calculation takes into account your home’s size, insulation, layout and location to find the right system size. Don’t just guess.

5. Inefficient Thermostat Use

Even a perfectly installed system can waste energy if it’s being controlled poorly. Setting the thermostat too low in summer or too high in winter makes the system work overtime.

What to do:
Set your thermostat to around 24–25°C in summer and 18–20°C in winter. Each degree cooler in summer can increase running costs by around 10%. Consider a programmable thermostat or a smart system that adjusts when you’re out of the house.

Seasonal Factors in Australia

The Australian climate isn’t one-size-fits-all, and that means heating and cooling needs are different from place to place. For example:

Melbourne or Hobart, heating is the main concern, and older systems can eat through electricity during long winters.
Perth or Adelaide, you might use more cooling, especially during heatwaves.
Queensland or the Top End, humidity control is a big part of keeping homes comfortable and efficient.That’s why you need to choose and maintain a system that suits your house and your local climate.

How to Improve HVAC Efficiency Without Replacing the Whole System

You don’t have to buy a new unit to stop wasting energy. Try these first:

Insulate and seal your home
Good insulation keeps warm or cool air in, reducing the load on your HVAC. Weatherstrip doors and windows too.
Use ceiling fans
Fans circulate air, making your home feel cooler or warmer without turning up the system.
Close off unused rooms
If you’re not using a room, there’s no need to cool or heat it. Shut the door and close the vent if your system allows.
Let the sun help
In winter, open curtains during the day to let the sun warm your home. In summer, use blinds or awnings to block out the sun.