Melbourne has a bit of a reputation for having unpredictable weather, but the real story is its ridiculously variable weather. The Bureau of Meteorology has data showing off how often the city goes from sizzling hot to seaside cold in just 48 hours, a swing that just doesn’t happen with the same regularity anywhere else in major Aussie cities. A system that just keeps on truckin’ in Sydney’s more steady climate or Perth’s dry summer heat isn’t going to automatically cut it in Melbourne, and understanding why that is and what it means for our homes is important for making smart decisions about heating and cooling.
Heating Gets a Raw Deal Every Year
It’s easy to assume we worry most about cooling in Australia, and Victorian government energy consumption data is there to tell us that’s a pretty bad assumption. In actual fact, space heating accounts for the biggest chunk of household energy use in Victoria, beating out cooling, even with our increasingly scorched summers. Most people will tell you to just get a Melbourne heating and cooling system that performs well in summer and it’ll be fine, but the truth is, it’s covering about half of what it’s actually going to be doing all year round.
Reverse cycle tech is the way to go. Unlike traditional heating systems, which burn fuel or whack on the electric element to kick out some heat, it just moves thermal energy around, grabs some heat from outside air in winter and reverses the process in summer. Current models of these systems are super efficient even at outdoor temperatures as low as 15 below, which covers Melbourne’s winters with plenty of room to spare.
What a System that’s a Bit Too Small Actually Does to a Home?
A system that’s installed too small doesn’t just underperform on the really bad days; it’s going to run flat out at full capacity all the time without actually getting the place to the right temperature. And that means it’s going to gobble up more electricity than a correctly sized system would at a much more reasonable level of operation, around 70 to 80 per cent During Melbourne’s killer heatwaves, which the Bureau of Meteorology records as averaging between 8 to 10 days above 35 degrees in the metropolitan area each year, a system that’s undersized is basically just drowning in its own sweat.
The compressor takes the real hit, in the end. Running flat out for too long just kills it, and that means your system lifespan will be shortened by years and years. So, the long-term investment where the money either pays off or quietly drains away is getting the system right, and that means proper capacity specification calculated from actual floor area, ceiling height, insulation quality, and the way the house is laid out in terms of windows and the like.
Period Housing and the Thermal Performance Problem
A lot of Melbourne’s inner-suburb housing stock is from before 1970, back in the day when insulation was just not a thing to think about. Victorian terraces, Edwardian bungalows, and interwar homes just lose conditioned air like nobody’s business in a way that modern construction just doesn’t. The system’s got to work a whole lot harder to get the house to the right temperature, which means it costs more to run. Now, the duct installation can be a lot easier with those big ceiling voids that are often found in older homes, but the problem is the house itself: single-brick walls, uninsulated ceilings, and all those big old windows just work against the system’s efficiency. A correctly sized system in a poorly insulated old home is going to cost more to run than the exact same system in a modern home that’s well-insulated, even if the two houses are the same size.
Zoning Changes the Discussion on the Cost of Operation
Without zoning, the operation of the ducted system conditions all parts of the house at once. With zoning, the separate zones are either switched on or turned off separately, thus only those zones that are used get the air conditioning. A family that spends the night in the bedroom zone and uses the living area zones only during the day can turn off all other unused zones completely.
The payback on zoned versus non-zoned ducted installation in Melbourne weather is around two to four years considering the average usage of houses. For homes in which different zones are used at different times of the day, zoning is not a luxury but an appropriate way of installing the air conditioner.
Why Split Systems Can’t Get Any Better in Melbourne?
A split system does a great job in cooling one zone. This is enough in case of a small studio apartment or a single open space. But if you have several rooms with different temperatures in a house, the only way a split system does this is to cool one room and leave the rest of the rooms at their ambient temperature. The only way to deal with it is to have a few split systems that run independently of each other with their own cost of energy, maintenance and installation. Having three split systems in a three-bedroom house in Melbourne will cost more than installing a zoned ducted installation.
Melbourne weather requires an installation of the system adjusted to all possible conditions and not only the extreme ones. Adjusting the system is much cheaper if done before the installation.
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