Air conditioning
in Hillarys
A 30 square metre living room in Hillarys needs about 4.47kW, against 5.38kW for the same room in South Hedland, because Hillarys peaks at 37.1°C where South Hedland hits 42.5°C. Installed prices here run $1,400–$3,600 for splits.
Get Hillarys quotes
Up to 3 licensed installers who work your postcode. Free, no obligation.
Why Hillarys is different
Sizing advice written for "Perth" is written for an average that barely exists. Hillarys accumulates 165.6 cooling degree days a year and clears 35°C about 19.7 days. South Hedland, across Perth, accumulates 1395.7 and clears 35°C about 153 days — roughly a 8 times lighter cooling load. 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 Hillarys
| Room | Approx size | Cooling needed | Unit to look for |
|---|---|---|---|
| Bedroom | 12m² | 1.79kW | 2kW |
| Large bedroom or study | 18m² | 2.68kW | 2.5kW |
| Small living area | 25m² | 3.72kW | 3.5kW |
| Living room | 30m² | 4.47kW | 4.2kW |
| Open-plan living and dining | 45m² | 6.7kW | 7.1kW |
| Large open plan | 60m² | 8.93kW | 9.5kW |
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
Hillarys sits in the Western Power network area, where a residential flat rate currently runs about 33.2621c per kilowatt hour (Synergy Home Plan (A1)). On that rate, a typical 3.5kW split system used normally costs roughly $117 a year in cooling, against about $641 for the identical unit in South Hedland.
That figure starts from the appliance's registered energy rating data, then scales it by Hillarys's own cooling degree days against the reference site the rating uses (Richmond RAAF (067105), 113 degree days). Without that adjustment every suburb in the zone would show an identical number, which would tell you nothing.
What changes a quote in Hillarys
Salt air shortens outdoor unit life here
Hillarys sits about 1.6km from the coast, and salt-laden air attacks aluminium fins and steel casings far faster than it does inland. Ask what corrosion protection the outdoor unit carries and read the coastal terms in the manufacturer warranty, because several brands reduce or exclude cover within a set distance of surf. That clause is worth checking before you choose the unit rather than after.
Sizing for 37.1°C, not for the average
Hillarys reaches 37.1°C on its hottest days and clears 35°C about 19.7 days a year. Every system loses output as the outdoor temperature climbs, so a unit specified against the nominal rating will disappoint exactly when you need it. Ask what the unit actually delivers at 40°C rather than at its test conditions.
Ducted is genuinely viable here
89.7% of Hillarys 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
Hillarys has a median age of 40 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.
Installed prices
| System | Installed price | Suits |
|---|---|---|
| Small split (2.5kW) | $1,400–$2,250 | Bedrooms and studies |
| Large split (5-7kW) | $2,350–$3,600 | Living areas |
| Ducted, whole home | $9,000–$15,000 | Houses with roof access |
Perth pricing. See the full Perth cost guide for a breakdown by job, or the Western Australia rebate guide for discounts that come off these figures.
About Hillarys
Around 11,774 people live in Hillarys (estimated for 2025), across roughly 11,726 occupied dwellings. The housing mix is 1% apartments, 89.7% separate houses and 9.1% 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 Hillarys's.
Sources and data
- ABS Census 2021, dwelling structure and medians by postcode
- ABS Regional population 2024-25 (population estimate basis)
- Bureau of Meteorology, Climate Data Online
- Australian Building Codes Board climate zone map
- AIRAH FairAir cooling calculator (design condition methodology)
- Consumer Data Right energy plan data (network and tariffs)
- energyrating.gov.au product database (zoned energy rating 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 SWANBOURNE (009215). Nearest qualifying station (still reporting, 33.0 yr of record, 99% complete). SWANBOURNE (009215) is 16.3 km away, 0.7 km from the open coast against the suburb's 1.6 km, at 41 m against the suburb's 24 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.