Colac 3250Climate zone 6 · Powercor

Air conditioning
in Colac

A 30 square metre living room in Colac needs about 3.99kW, against 3.11kW for the same room in Portland, because Colac peaks at 34.3°C where Portland hits 29.1°C. Installed prices here run $1,450–$3,700 for splits.

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Why Colac is different

Sizing advice written for "Melbourne" is written for an average that barely exists. Colac accumulates 34.4 cooling degree days a year and clears 35°C about 8.5 days. Portland, across Melbourne, accumulates 10.1 and clears 35°C about 2.5 days — roughly 3 times the cooling demand. That is why the same room needs a different size unit depending which suburb it sits in, and why a number quoted for the metro average will be wrong for most addresses in it.

What size you need in Colac

Room	Approx size	Cooling needed	Unit to look for
Bedroom	12m²	1.6kW	2kW
Large bedroom or study	18m²	2.4kW	2.5kW
Small living area	25m²	3.33kW	3.5kW
Living room	30m²	3.99kW	4.2kW
Open-plan living and dining	45m²	5.99kW	6kW
Large open plan	60m²	7.98kW	8kW

Sizing follows the design criterion AIRAH uses in its FairAir calculator: the 3pm outdoor temperature exceeded on no more than 10 days a year. We compute that figure for each suburb from Bureau of Meteorology daily records, then split the cooling load into a component that scales with how far the design temperature sits above 24C and a component from sun and internal heat that barely varies by location. That 50/50 split is our assumption, not AIRAH's. Treat the result as a starting point for a quote, not a substitute for an installer measuring your rooms.

What it costs to run here

Colac sits in the Powercor network area, where a residential flat rate currently runs about 28.22c per kilowatt hour (AGL Residential Standing Offer). On that rate, a typical 3.5kW split system used normally costs roughly $43 a year in cooling, against about $6 for the identical unit in Portland.

That figure comes from the energy rating scheme's own registered consumption figures, measured across three Australian reference climates and fitted to Colac's 34.4 cooling degree days: about 111.4 kilowatt hours a year regardless of climate, plus 1.16 per degree day, then charged at the local tariff. The fixed part matters, because a running air conditioner draws power for standby and part-load cycling even where there is barely any cooling to do — which is why the mildest suburbs still cost something rather than nothing.

Watch the peak window.

On a time-of-use plan in this network, electricity between 15:00 to 21:00 costs about 40.4c against 23.65c off-peak. Cooling the house hard through that window is where summer bills actually get away from people. Pre-cooling before it starts costs noticeably less.

Local factors

What changes a quote in Colac

You probably need less than you think

Colac accumulates only 34.4 cooling degree days a year and clears 35°C about 8.5 days. Oversizing is the common and expensive mistake here: too much capacity short-cycles, dehumidifies poorly and costs more upfront and to run. If an installer quotes a size up without measuring the room, ask them to justify it.

Winter matters as much as summer

With 1805 heating degree days and July mornings averaging 5.4°C, a reverse-cycle system in Colac earns its keep for heating at least as much as cooling. Ask for the heating output at low ambient temperature rather than the nominal kW, because that figure is what determines whether it copes on the coldest mornings.

Ducted is genuinely viable here

88.1% of Colac dwellings are separate houses, most with accessible roof space, which makes ducted a real option rather than a stretch. The check that matters is roof cavity height and insulation condition, and any installer can confirm both in a five-minute inspection before quoting.

Established housing, check the switchboard

Colac has a median age of 42 and correspondingly older housing stock. The thing that catches people out is electrical: an older switchboard may not have a spare circuit for a large system, and that upgrade is legitimate money rather than an upsell. Ask for it to be itemised separately in the quote so you can compare like with like.

The peak window costs real money here

On a Powercor time-of-use plan, electricity runs about 40.4 cents during the peak window (15:00 to 21:00) against 23.65 cents off-peak, close to double. Cooling the house hard through that window is where summer bills get away from people in Colac. Pre-cooling before it starts costs noticeably less for the same comfort.

Installed prices

System	Installed price	Suits
Small split (2.5kW)	$1,450–$2,300	Bedrooms and studies
Large split (5-7kW)	$2,400–$3,700	Living areas
Ducted, whole home	$8,000–$16,000	Houses with roof access

Melbourne pricing. See the full Melbourne cost guide for a breakdown by job, or the Victoria rebate guide for discounts that come off these figures.

About Colac

Around 9,141 people live in Colac (estimated for 2025), across roughly 5,127 occupied dwellings. The housing mix is 0% apartments, 88.1% separate houses and 10.7% semi-detached or townhouses, which is what drives most of the practical differences in getting a system installed here.

Nearby suburbs

Climate, network tariffs and housing stock shift across a metro, so the sizing and running costs on these pages differ from Colac's.

Sources and data

Based on Australian Bureau of Statistics data. Source: ABS, Census of Population and Housing 2021 and Regional population 2024-25, licensed under CC BY 4.0. Climate data: Bureau of Meteorology, licensed under CC BY 4.0. Climate zones: Australian Building Codes Board. Tariffs: Consumer Data Right energy plan data. Appliance energy data: energyrating.gov.au (E3 Program).

Population is an estimate derived from the 2021 Census count scaled by regional growth to 2025, not an official count. Climate figures come from COLAC (MOUNT GELLIBRAND) (090035). Nearest qualifying station (still reporting, 26.2 yr of record, 99% complete). COLAC (MOUNT GELLIBRAND) (090035) is 21.6 km away, 34.8 km from the open coast against the suburb's 40.8 km, at 261 m against the suburb's 137 m. Stations are ranked on distance plus penalties for differing coastal exposure, elevation, NCC climate zone, record length and marine (sand-spit or island) siting.

Air conditioning in Colac: questions

What size air conditioner do I need in Colac?

For a typical 30 square metre living room in Colac, about 3.99kW, which in practice means a 4.2kW unit. Bedrooms usually land around 2kW. That comes from Colac's design temperature of 34.3°C, against 29.1°C in Portland, which is why the same room needs a different size in each. Any installer should still measure the room, since orientation, glazing and insulation move the answer.

What does it cost to run air conditioning in Colac?

Roughly $21 a year in cooling for a typical 3.5kW split used normally, on Powercor network rates of about 28.22 cents a kilowatt hour. That figure starts from the appliance's registered energy rating and is then scaled by Colac's own cooling degree days against the reference site the rating uses, because without that adjustment every suburb in the zone would show an identical number. If you are on a time-of-use plan, the peak window is where summer bills actually get away from people.

Can I get ducted air conditioning in Colac?

Usually yes. 88.1% of Colac dwellings are separate houses, and most have the roof access ducted needs. The practical checks are cavity height, insulation condition and whether your switchboard can carry the load, all of which an installer confirms on a short site visit before quoting.

When is the cheapest time to install in Colac?

The shoulder seasons, and in Colac that means autumn or early spring. Demand here peaks twice, for cooling in summer and heating in winter, so the quiet windows sit between them. Quoting in a quiet window gets sharper prices and avoids the queue that forms after the first extreme day of either season.

Air conditioning in Colac