The average Tasmanian four person home consumes a whopping 8813 kWh a sq m on average. The national average is 5915 kWh a sq m.

UPDATED: The European Union has mandated that all new buildings be NZEBs from the 31st of December 2020. But look at how Aussie’s energy consumption compares. Here’s a hint: not good.

Unlike our Australian system where building codes and standards are modified and in some cases ignored by state governments at their leisure, the EU sets concrete goals that more often than not include hefty fines if their directive is not adhered to.

The latest initiative is the NZEB compliance

With a break from tradition the EU has allowed each member state to determine its own definition and benchmarks on how it will be achieved but it has not relinquished control.

For instance the EU has recommended that member countries in the Oceanic Zone, like Ireland, should consume a maximum of 50-60 kWh per square metres per year of primary energy use for housing while generating 35 kWh per sq m per year of on-site renewables.

For non domestic users, those figures are 85-100kWh per sq m per year with 45 kWh per sq m per year of renewables.

Before you grab your calculators to draw a comparison remember we are talking primary energy not end-use energy.

 Conversion rate or energy losses is broadly accepted at a factor of 3.3  So two thirds of the original potential energy is lost in conversion to end use, or by the time it gets to your house.

So, to put these into perspective:

  • The Irish residential cap of 50-60 kWh per sq m per annum equates to 15.5-18.2 kWh per sq m end use energy per annum.
  • Considering an average Australian home as about 250 sq m. Our annual consumption of end use energy, should be between 3875 kWh and 4550 kWh if equated to the Irish target.

In Australia our national average annual end use energy consumption is  5915 kWh (according to ACIL Allen Consulting AER electricity distribution data).

This puts us well above the markers suggested by the EU.

By way of fair comparison let’s consider an Australian climate comparable to Ireland.  Tasmania is as close as you’ll get. Tasmania’s energy use for the average home is a whopping 8813 kWh. Surely, we can do better!

The EU has focused on airtightness as a key pathway to achieving NZEB. The TGL in Ireland, our equivalent is Section J, has an upper limit of air lost through the building fabric of 5 cubic metres an hour per sq m. per annum

This is down on the 7 cubic metres per hour per sq m set in 2011.

To put this in context our NatHERS modelling tool, which sets the benchmark for our energy efficient homes, assumes an air tightness of between 12 and 15 air changes an hour. That’s higher than the 2005 level in Ireland.

Additionally, under the EU directive  it will be mandated that every new, single dwelling home and apartment , must have a blower door test performed with both pressurised and depressurised testing conducted.

The Irish path to today’s performance

Test results for homes undergoing blower door testing in Ireland

  • 2005: 11.8 cubic metre an hour per sq m
  • 2017: 3.66 cubic metre/h  per sq m
  • 2019: 2.85 cubic metre/h  per sq m

This stellar improvement was a result of a committed Industry and a phased introduction.

Why do we need to have air tightness down at these levels?

Wherever you are in Australia you are either heating or cooling your home for at least 50 per cent of the year. You are pumping energy and money into your home to maintain a pleasant temperature only to find that 12-15 times an hour, most of that air is bringing comfort to the birds in the trees.

It is leaking like the proverbial sieve. There is a huge opportunity for Australian construction to push forward with a fabric first approach. Simply put we need to make sure out outer walls, ceiling and floor are well constructed with low leakage to contain the conditioned air and the energy bills.

There is a sizable body of evidence to show that homes performing in the 5m3/hr/m2 sector have better indoor air quality (significantly reducing smoke infiltration) and dramatically reduce the risk of dampness and mould given that the mechanical system can guarantee a consistent level of quality, humidity controlled air, when the house is closed up.

Finally, that damp air is prevented from getting into your structure and rotting it over time. It’s a no brainer.

The Australian Building Industry has to start driving change and hence control its introduction to a sensible pace.

We must break the shackles of the “it’s not broken so we don’t need to fix it” attitude. This innovation will pay dividends for the rest of the life of the home through healthier indoor environments and lower energy bills.

Show me how a granite bench top or a steam oven can offer the same gain. It is acceptable to add cost to a home if you are doing it for the right reasons.

The market understands what, healthy internal environments, comfort and return on investment means, and are willing to pay a small amount to reach it.

John Moynihan is a director of Ecolateral and Air Tightness Testing Services Australia (ATTSA), a member of the Australian Passive House Association and a Level 2 Accredited ATTMA certified Air Tester.

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  1. Very interesting article! We will only get energy efficient homes when we keep air infiltration as low as possible. Good for the pocket and good for comfort.