Evaporative cooling and refrigerated air conditioning solve the same problem — reducing indoor temperatures on hot Melbourne days — through fundamentally different processes. For Melbourne homeowners choosing a system or deciding whether to replace an existing evaporative cooler, the comparison comes down to running costs, humidity performance, air quality, and how your specific home is built. This guide covers each factor with Melbourne-specific detail.
How the Two Systems Work
Evaporative cooling
An evaporative cooler draws hot outside air through water-saturated pads. Evaporation removes heat from the air and lowers its temperature by 8 to 14°C under ideal conditions. The system runs continuously on outside air — it does not recirculate indoor air and requires windows to be open to allow the high air volume to exit. The only energy input is the fan motor and small circulating pump — typically 250 to 600 watts total for a residential system.
Refrigerated air conditioning
A refrigerated system (split system or ducted reverse cycle) uses a sealed refrigerant circuit with a compressor, condenser coil, and evaporator coil to extract heat from indoor air and reject it outside. The system recirculates indoor air — it does not need windows open and can cool regardless of outside humidity. The compressor is the dominant power draw, typically 1,500 to 5,000 watts for residential systems. Modern inverter systems modulate the compressor to match load, improving efficiency at part capacity.
Running Costs in Melbourne
Running cost is the most significant practical difference for Melbourne homeowners. Using Melbourne’s average residential electricity rate of approximately 30 cents per kWh in 2025:
| System | Typical Power Draw | 8-hr Run Cost | 60-day Season Cost |
|---|---|---|---|
| Evaporative cooler (residential) | 300–600 W | $0.72–$1.44 | $43–$87 |
| Ducted refrigerated (medium home) | 3,000–5,000 W | $7.20–$12.00 | $432–$720 |
| Split system (single room) | 800–2,000 W | $1.92–$4.80 | $115–$288 |
Over a Melbourne cooling season, a household running an evaporative cooler instead of ducted refrigerated air conditioning saves approximately $400 to $700 in electricity costs. Annual maintenance (service, pads, winterising) runs $930 to $1,460 per year — more than the refrigerated system’s filter-only maintenance, though the evaporative system’s much lower installation cost typically offsets this over its service life. Evaporative coolers also use water — typically 8 to 25 litres per hour — adding approximately $15 to $40 per season at Melbourne’s water rates.
Melbourne Climate Suitability
Melbourne’s climate creates a clear seasonal picture for both systems. The city’s hottest days arrive on dry northerly winds from interior Victoria with relative humidity of 15 to 25 per cent — ideal evaporative cooling conditions. The Melbourne cool change — the southerly wind shift that follows extreme heat events — brings more humid air (50 to 75 per cent relative humidity) where evaporative cooling is less effective. However, the temperature itself drops with a cool change, so cooling demand is also reduced.
The overall picture: for the typical Melbourne established home, evaporative cooling provides adequate comfort on approximately 80 to 90 per cent of summer cooling days at a fraction of the running cost of refrigerated cooling.
Melbourne’s established 1950s to 1980s brick homes in the eastern, south-eastern, and northern suburbs — Doncaster, Glen Waverley, Ringwood, Frankston, Reservoir, Greensborough — have the ceiling heights and openable windows that suit evaporative cooling well. Newer sealed townhouses and apartments in inner Melbourne are better suited to refrigerated systems.
Installation Costs Compared
For Melbourne homes that already have ductwork from a previous evaporative cooler, replacement installation is significantly cheaper than installing a new refrigerated ducted system. A Brivis or Seeley/Breezair evaporative replacement unit into an existing duct system costs approximately $1,500 to $3,000 installed. A new ducted reverse cycle system requires refrigerant piping, outdoor unit installation, and new ductwork — typically $5,000 to $12,000 for a medium Melbourne home.
For new installations with no existing ductwork, a new evaporative cooler with duct installation for a medium Melbourne brick home costs $3,000 to $5,000. Ducted reverse cycle for the same home: $8,000 to $15,000. A high-wall split system for a single room can be installed for $1,200 to $2,500.
Air Quality and Ventilation
Evaporative cooling continuously flushes indoor air with fresh outside air — typically achieving two to three complete air changes per hour in a well-ventilated Melbourne home. This keeps CO levels low in occupied rooms and removes cooking odours and other indoor pollutants. The main air quality limitation is that outside air quality determines inside air quality — on high-smoke days (Melbourne’s occasional bushfire smoke events in January and February) or high-pollen spring days (November to December for grass pollen), the evaporative cooler introduces these particles.
Refrigerated systems recirculate indoor air through a filter. Higher-grade filters (MERV 11+ or HEPA-rated) can significantly reduce indoor pollen and particulate levels — important for Melbourne households during the severe spring pollen season. On smoke days or high-pollen days, closing the home and running a refrigerated system with a quality filter is the preferred approach.
Which System Suits Your Melbourne Home
Evaporative cooling suits
- 1950s to 1980s brick homes in Melbourne’s eastern, south-eastern, and northern suburbs — Box Hill, Doncaster, Ringwood, Croydon, Frankston, Greensborough, Reservoir
- Victorian and Edwardian homes with high ceilings and multiple openable windows — Carlton, Brunswick, Fitzroy North, Northcote
- Households primarily concerned with summer cooling rather than year-round conditioning
- Homes already with existing evaporative duct infrastructure
- Households with high electricity costs seeking the lowest running cost option
Refrigerated cooling suits
- Newer sealed townhouses and apartments in inner Melbourne, Richmond, Fitzroy, South Yarra, and other inner suburbs
- Households that need year-round heating and cooling in one system (reverse cycle)
- Households with pollen allergy or asthma sufferers who benefit from filtered recirculated air on high-pollen days
- Homes on the Melbourne bay coast (Port Melbourne, Williamstown, Brighton) where summer humidity reduces evaporative cooling effectiveness
Many Melbourne homes use both: an evaporative cooler for the majority of summer cooling at low running cost, and a split system in the main living area for the minority of high-humidity days and for winter heating. See our evaporative cooler running costs guide for a detailed Melbourne cost model.