Letter to the Editor: Missing from much discussion of energy efficient housing is the answer to a simple question – how much extra will this energy efficient home actually cost? This is odd because Australia has a crisis in housing costs – the average price has just passed $1M. Any design method that further increases the cost of building a new home simply makes that approach irrelevant to the vast majority.
Passivhaus, Structural Insulated Panel (SIP), Cross-Laminated Timber (CLT) – all cost more than typical Australian house construction. To put that another way, many people promoting energy-efficient housing are catering only for the rich. However, this appears to be rarely stated.
Passivhaus proponents, for example, often talk about minimal cost increase – e.g. 7 per cent. However, when the construction approach is examined in detail (i.e. Passivhaus-specific walls, floors, ceiling, windows and external doors), the extra materials are included (e.g. insulation and a mechanical ventilating system), and Passivhaus architecture, testing and accreditation are added, that percentage increase doesn’t appear possible.
In fact, it appears it is a 7 per cent cost increase over an architect designed, premium house – not a normal Australian home.
One major Australian Passivhaus builder lists the cost of building their last 18 Passivhaus at $6153 sq m. This site suggests the average cost of building an Australian home is $1,800 – $4,500 sq m. If we take a middle figure of $3150 per square metre, that makes a Passivhaus from that company very close to double the price of a normal Australian house.
Even if we work from the other end and look at the likely cost of each of those Passivhaus specific construction techniques and other costs, we still end up with a 50 per cent, or thereabouts, premium over a normal Australian house.
I haven’t done the calculations for SIP and CLT – but the fact that it’s nearly impossible to get a simple answer to the question, “How much more will this cost than a normal Australian home?” is the giveaway.
However, there is an approach to energy efficient housing that costs no more than a standard, current build Australian house.
That approach is to use passive solar design principles. It is also the approach recommended by the Federal and State governments for all southern states.
Window size and position, insulation, shading and internal thermal mass are the fundamentals. And none of these needs to add any cost at all. No higher material costs, no non standard construction, no need for specialised (and expensive) tradespeople.
Those promoting energy efficient housing need to be far more upfront about the costs of their approach. If you are promoting energy efficient house designs that suit only the rich, just say so.
Julian Edgar
Dalton, NSW