Ducted ventilation and air purification: HRV, ERV and ducted filters explained

What is ducted ventilation? Heat recovery ventilation explained

YourHome, the federal government's guide to sustainable homes, describes mechanical ventilation heat recovery as a total ventilation system for well-sealed homes. It draws in outdoor air, extracts humid indoor air, and uses a heat exchanger so the outgoing air warms or cools the incoming air. It supplies filtered outdoor air to living rooms and bedrooms while extracting air from bathrooms, kitchens and laundries.

The air is filtered as it enters and leaves, which YourHome notes is especially useful when pollution or pollen is high. The unit runs continuously at low speed, so the house gets a steady trickle of fresh air instead of an open window.

The hardware is a box in the roof or a cupboard with two fans, a heat exchanger core and filters. It connects to four ducts: fresh air in from outside, supply air to the rooms, extract air from the wet areas, and exhaust air out.

Heat recovery ventilation vs energy recovery ventilator: which suits your climate?

The difference is moisture. An HRV passes heat between the two airstreams. An energy recovery ventilator (ERV) passes heat and some moisture as well.

That makes an ERV worth a look in humid places such as Brisbane, the Gold Coast or the tropics, where it limits how much outdoor humidity comes in with the fresh air. An HRV suits cooler climates, where getting moisture out of the house in winter is the point. Your designer should choose based on the climate zone and how tight the house is.

Do 7-star homes need a whole house ventilation system?

The National Construction Code 2022 lifted the minimum thermal performance for new homes to the equivalent of 7 stars under NatHERS, plus a whole-of-home annual energy budget. The ABCB says the higher standard applies from 1 October 2023 in most states and territories. Check the date that applies where you are building.

Tighter, better insulated homes hold heat and moisture. The ABCB puts it plainly: well-sealed buildings with poor ventilation can have increased condensation risk, while buildings that are both well sealed and adequately ventilated manage condensation well. NCC 2022 added condensation rules for housing, including exhaust from kitchens, bathrooms and laundries discharging outdoors, a 10 minute run-on for exhaust fans in bathrooms without enough natural ventilation, and roof space ventilation in climate zones 6, 7 and 8.

The code sets those minimums. It doesn't require a heat recovery system in every 7-star home. YourHome notes some consensus that a home tested below 3 to 7 air changes per hour at 50 pascals (ACH50) definitely needs mechanical ventilation, and that some old houses leak at over 30. If your builder is chasing airtightness with a blower door test, ask what ventilation goes with it.

• New build aiming for high airtightness or Passive House: plan HRV or ERV from the start, with the ducts run before the plasterboard goes up.
• Standard 7-star build: good exhaust fans that vent outside may be enough; ask the designer about condensation risk in your climate zone.
• Older, leaky house: ventilation is rarely the problem. Sealing, insulation and a well-sized reverse cycle system usually come first.

Ducted air purifier options: return-air filters, electrostatic, UV and HEPA

If you have ducted reverse cycle and want cleaner air in every room, filtration at the return grille is the usual starting point. All the air comes back through it, so a better filter there treats every zone that's running. Our air purification guide covers what split systems do by comparison.

• Upgraded return-air filter: a pleated or higher-grade media filter in place of the standard mesh. The cheapest step, and easy to maintain.
• Filter box: a separate housing in the roof that holds a deeper filter, so it catches more without choking the airflow.
• Electrostatic filter: charged media that attracts fine particles. Some are washable. Ask how often it needs cleaning to keep working.
• UV lamp at the coil: aimed at mould and bacteria growing on the wet coil. It doesn't filter particles from the air.
• Maker add-ons: Mitsubishi Electric sells Plasma Quad Connect for selected ducted units, and Panasonic's NX Series ducted, launched in November 2025, has nanoe X built in, according to each maker.
• HEPA-grade: a true HEPA filter is dense. Most home ducted fans can't push enough air through one, so a ducted HEPA filter usually means a bypass unit with its own fan, or a high-grade filter short of HEPA.

The catch with any denser filter is airflow. The fan has to work harder, and a choked return means noisy vents and a system that struggles on hot days. Ask the installer to confirm the fan can handle the filter and to write the filter type and grade on the quote. The National Asthma Council's mould advice suggests high-efficiency filters, whether built into air conditioning, heat recovery ventilation or a purifier.

How ventilation works with ducted reverse cycle air conditioning

The two systems do different jobs. The ventilator changes the air. The ducted air conditioner heats and cools it. In most homes the HRV or ERV has its own small ducts to ceiling vents, separate from the air conditioning ducts, and the ducted system runs as normal.

Some designs feed the ventilator's fresh air into the ducted system's return instead. That can save duct work, but the two fans interact, so it needs careful design and matched controls. Ask whoever designs it to show where the fresh air enters and how the controls stop the systems fighting.

Humidity control stays with the air conditioner. In humid climates, dry mode and correct sizing do most of the work; see air conditioner vs dehumidifier. For the ducted side itself, including zoning and controllers, see our ducted air conditioning guide. To price both together, get up to three local quotes.

How much does a whole house ventilation system cost?

We haven't found an official or manufacturer source that publishes installed prices, so treat these as indicative bands only. The house, the roof space and whether it's a new build decide the number.

Retrofit is dearer because the ducts have to find a way through a finished house. If you're building, price ventilation with the ducted system at the design stage. Get up to three local quotes and compare what each includes: unit, duct runs, filters, controls and commissioning.

Installation and maintenance

Installation is mostly duct work. The unit goes in the roof or a service cupboard, with supply vents in bedrooms and living areas and extract points in the wet areas. After install, the system should be balanced so supply and extract airflows match. Ask for the commissioning figures in writing. Electrical work must be done by a licensed electrician, and any refrigerant work on the air conditioning side by an ARCtick-licensed technician; see ARCtick explained.

Maintenance is mainly filters. An HRV or ERV has filters on both airstreams, and they clog faster near busy roads or in pollen season. Follow the maker's schedule. For ducted air conditioning, YourHome recommends cleaning the ducts and air filters regularly, for example at the start of each heating or cooling season.

• Check and clean or replace ventilator filters on the maker's schedule, often every few months.
• Clean the ducted return-air filter at the start of each season.
• Keep outdoor intake and exhaust hoods clear of leaves and cobwebs.
• Book a service if airflow drops, vents whistle, or it smells musty.

Our quote checklist covers what else a ducted quote should list. When you're ready, get up to three local quotes.