---
title: "What Is Heat Recovery Ventilation, and Does an Australian Home Need It?"
date: 2026-09-06T16:30:00+10:00
author: Darren Burch
canonical_url: "https://sogeo.com.au/blog/what-is-heat-recovery-ventilation-australian-homes"
section: Pages
---
![Stiebel Eltron LWZ 180 heat recovery ventilation unit installed in a hallway cupboard with ducts running up from the top of the unit]()

#  What Is Heat Recovery Ventilation, and Does an Australian Home Need It? 

Heat recovery ventilation brings a continuous supply of filtered fresh air into a home and recovers most of the heat from the stale air it removes. Here is how an HRV system works, how it differs from ERV, what it costs to run, and when a well sealed Australian home needs one.

 

 

 

 **Short version first.** A heat recovery ventilation (HRV) system is balanced mechanical ventilation. One fan continuously extracts stale, humid air from the kitchen, bathrooms and laundry. A second fan supplies filtered fresh air to the bedrooms and living areas. On the way past each other the two air streams pass through a heat exchanger that transfers most of the heat from the outgoing air into the incoming air, without the two streams ever mixing. The result is fresh air all day, every day, without throwing away the heat you paid for. In a modern, well sealed home it is the missing piece. In a draughty older home it is usually not the first thing to fix.

## What a heat recovery ventilation system actually does

An HRV system has five parts: a supply fan, an extract fan, a heat exchanger core, filters on both air streams, and ductwork that reaches every room. The extract ducts pull air from the wet and smelly rooms, the supply ducts deliver fresh air to the rooms where people spend their time, and the unit sits in a cupboard, a roof space or a plant room with a drain for the condensate that forms when warm, humid indoor air meets the cold core in winter.

![Heat recovery ventilator diagram: fresh air in, stale air out, with a filter, fan and heat exchanger in between](https://sogeo.com.au/uploads/general/heat-recovery-ventilation-diagram.png)

The word balanced matters. The system moves the same volume of air in as it takes out, so the home is never under pressure or suction, doors do not slam, and there is no draught. It runs continuously at a low speed that you will not hear, with a boost setting for cooking or a houseful of guests. Because the heat exchanger recovers most of the energy in the outgoing air, the incoming fresh air arrives already close to room temperature. Depending on the unit, a good heat exchanger recovers somewhere between 75 and 90 percent of that heat.

## Why sealed homes need it

For most of the last century Australian homes ventilated themselves by accident, through gaps around windows, floorboards, downlights and unsealed wall cavities. That leakage wasted heat, but it also kept the air fresh. New homes are built differently. A home built to current energy standards is far more airtight, and a home built to a passive house standard is sealed deliberately. Seal a home properly and the leakage that used to ventilate it is gone, so the moisture from showers, cooking and breathing has nowhere to go. The symptoms are familiar: condensation streaming down winter windows, mould in the corners of bedrooms and wardrobes, a stale feeling in the morning, and carbon dioxide levels that leave people foggy.

Opening windows fixes the air quality and destroys the heating bill. Heat recovery ventilation fixes the air quality while keeping the heat in, which is why it is standard in high performance homes in Europe and increasingly specified on Australian new builds and major renovations. The filters are a bonus that owners in Melbourne notice quickly: pollen, dust and bushfire smoke stay outside.

 

 

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 ![Cutaway of a two storey home with a heat recovery ventilation unit in the roof space, extract ducts from the bathroom, kitchen and laundry, and fresh air supply ducts to the bedrooms and living room]() 

 

### Where HRV earns its keep: the Coimadai result

Ventilation that gives heat back is part of why a geothermal home measured a SCOP of 8.1.

Terry and Lynne Lefoe’s new build in Coimadai runs geothermal underfloor heating and cooling alongside a heat recovery ventilation system, and the system as a whole measured a seasonal coefficient of performance of 8.1, the highest of any project SóGeo has published. The ventilation is part of that number. On a well sealed home, the HRV unit recovers the heat that would otherwise leave with the exhaust air, so the heating load the heat pump has to meet is smaller. A smaller load means the inverter compressor spends more of its life at part load, which is where heat pumps are most efficient. The [Coimadai case study](/case-studies/case-study-sogeo-revolutionised-home-comfort-in-coimadai-victoria) has the full picture.

That is the way to think about HRV: it is not a heater and not a cooler, it is the thing that stops a good heating and cooling system from working harder than it needs to.

 

 

 ## HRV or ERV: which one for an Australian climate?

You will see two abbreviations. A heat recovery ventilator (HRV) transfers heat only. An energy recovery ventilator (ERV) uses a core that transfers moisture as well as heat, so in summer it keeps some of the outdoor humidity out, and in a dry heated winter interior it keeps some of the indoor moisture in. In the United Kingdom and Europe the same equipment is often called MVHR, mechanical ventilation with heat recovery, which is why that term turns up in Australian searches too.

For Melbourne and most of southern Victoria, where winters are cool and dry and the main job is recovering heat and getting rid of excess moisture, HRV is the usual choice. Humid coastal and northern climates lean toward ERV. The right answer is a design decision based on the climate, the home and how it is heated and cooled, not a preference for one box over another.

## What it costs to run

Very little. The fans in a residential HRV unit draw tens of watts on their normal setting, comparable to a handful of LED lights, and the heat they recover is worth far more than the electricity they use. The ongoing cost that owners forget is the filters, which need changing once or twice a year depending on the air outside. Skip the filters and the airflow falls, the core clogs and the recovery drops, so treat them like the oil in a car.

## What it costs to install

The unit is the smaller part of the price. The ductwork, the plant space and the access to run ducts to every room drive the cost, which is why a new build or a major renovation is the cheapest time to add HRV and a finished single storey home on a slab can be the hardest. Ask any installer for a design, not a unit price: a system with undersized or badly routed ducts will be noisy, out of balance and unable to recover what the brochure promises. SóGeo quotes ventilation from the drawings alongside the heating and cooling design.

## Does your home need it?

Heat recovery ventilation earns its place when several of these are true:

- You are building new, or renovating to a high energy rating, and the home will be sealed properly.
- You already see condensation on winter windows or mould in wet areas and bedrooms.
- Someone in the house has asthma or allergies, or you keep the windows shut for noise, security or bushfire smoke.
- The home runs on a heat pump, geothermal or air source, where every kilowatt of avoided heating load shows up on the bill.

It earns its place less on a draughty period home that has never been sealed. Fix the leakage first, because an HRV system cannot recover heat that is escaping through the floorboards. Once the envelope is tight, ventilation becomes the next step rather than an afterthought.

## How SóGeo approaches ventilation

We install a range of heat recovery ventilation units and select the unit to suit the home’s size, layout and climate rather than fitting one brand to everything. Ventilation is designed alongside the heating and cooling, so the duct routes, the plant space and the heat load are considered together from the first site visit, the same way we design a geothermal or hydronic system to the home rather than to a catalogue. The result is fresh air you never think about and a heating system that works less for the same comfort. Our [heat recovery ventilation service](/heat-recovery-ventilation) covers HRV on its own or as part of a heating and cooling project.

*SóGeo designs and installs heat recovery ventilation alongside geothermal and hydronic heating and cooling across Melbourne and regional Victoria. If your project is sealed, or about to be, ventilation belongs in the design conversation.* [*Talk to SóGeo about ventilation for your home*](/contact-us)*. Choosing the rest of the system:* [*geothermal heating and cooling systems in Australia*](/blog/geothermal-heating-and-cooling-systems-australia-guide)*.*

 

 

  ## Common questions about heat recovery ventilation

  ### What is the difference between HRV and ERV?

 ➕ HRV recovers heat only. ERV recovers heat and transfers some moisture between the air streams, which helps in humid summers and very dry winter interiors. Melbourne homes mostly suit HRV; humid climates lean toward ERV.

   ### Does heat recovery ventilation heat or cool the house?

 ➕ No. It ventilates. It reduces the heating and cooling load by recovering energy from the outgoing air, so the heating and cooling system works less, but it is not a substitute for either.

   ### How much heat does an HRV system recover?

 ➕ Depending on the unit and the conditions, a good heat exchanger recovers between 75 and 90 percent of the heat in the outgoing air.

   ### Can heat recovery ventilation be retrofitted?

 ➕ Often, yes, where there is roof space, a subfloor or a ceiling void to run ducts through. Access decides the cost more than anything else, and a renovation that already has ceilings open is the ideal moment.

   ### Does HRV stop condensation and mould?

 ➕ Continuous extraction from wet areas and a constant supply of dry, filtered fresh air removes the moisture that condensation and mould feed on. On a sealed home it is the most effective fix there is.

  

 

  

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