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ERV Heating and cooling ventilation for 7+ Star builds

22 Dec
ERV Heating and cooling ventilation for 7+ Star builds
Air Conditioning


If you're looking to build a home with energy efficiency higher than a normal 6 star home, we suggest you consider Energy Recovery Ventilation (ERV) coupled with some small heating/cooling input such as a reverse cycle air conditioner.

Whilst hydronic heating and cooling is luxuriant and comfortable, when you move to a 7 star design, your heating and cooling requirement becomes a lot less, obviating the need for substantial heating and cooling systems.

It is very difficult to achieve a completely passive home given the extremes of hot or cold weather in southern, inland or alpine locations of Australia, and with more extremes expected with global warming. However, a ducted ERV system will give you comfort all year round including those extreme weather days (hot or cold). These systems provide both energy efficiency and comfort.

If you are looking to go off-grid, then it is worth considering a 7+ star home design, air conditioned with a ducted ERV system with very little energy requirement plus a small heating/cooling appliance such as a reverse cycle air conditioner.

The ERV system can bring in outside air when it is opportune to do so. In summer, the overnight temperature may be around 22-24 degrees before soaring into the thirties again during the day. The ERV system will ensure the house starts the day at the optimal temperature by drawing in this optimal outside air, then the superior house design, being very well insulated and air tight, will maintain this temperature through the day with possibly no additional input from the air conditioner.


An ERV system preserves the humidity inside your home and is a better choice for southern, inland or alpine areas. To be comfortable, the humidity inside your home needs to be in the Goldilocks zone, not too dry and not too wet. 

Heat Recovery Ventilation (HRV) is similar to ERV but will reduce the humidity of the air inside your home and this may not be the best option if you live in an area where the humidity is usually low. 

Both ERV and HRV systems bring fresh outside air into your home and exhaust stale air out whilst recovering heating or cooling energy from the stale exhaust air.


Because you are setting up a ducted system, the cost of laying out the ducting is similar to that of a ducted air conditioner. However, you don’t usually need to run a ducted air conditioner as well. You can place an indoor unit in the main living room and the cooling or heating from there can be distributed around your home through the ERV system. In terms of budget, you are looking at around $20k supplied and installed for a 200m2 home plus the air tightness test and the air conditioner, depending on build complexity. Hydrosol can provide an indicative quote for you: 


If you proceed with an ERV system, you will need to make sure your home is sufficiently air tight, otherwise the ERV system will not work effectively. Your air tight house will still breathe via the ERV system, so it always feels fresh and airy. 


Your house design is the first and most critical aspect for an ERV system including orientation, shading, insulations levels and air tightness in the building fabric. Getting these things right can reduce your heating and cooling costs. It could be 5 times more efficient than a ‘’leaky’’ home.


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