New houses in Western Australia are being constructed below the minimum energy performance rating for Australian homes.

While WA sticks to the minimum six-star NatHERS requirement like other areas, the standard can be the focus of a deemed to satisfy method, and this inspires a trend to take advantage of loopholes in the system. The result is a collection of houses with an equivalent energy rating as low as two stars NatHERS.

The abuse of the alternative solution to tick off energy performance, titled the verification using a reference building (VURB) method, results in the house not needing a NatHERS star rating.

Western Australian eco-effective architect Sid Thoo states that by utilising this method, it can seem feasible to build a compliant structure with no cavity wall insulation nor thermally efficient windows.

While the reference building method has been discovered to be misused in other regions of Australia, Thoo states it’s frequent in his native state.

He states that the issue originates from WA’s home building market being occupied by some influential building firms that would prefer to keep building cavity brick houses with minimal insulation even if it produces higher energy bills for customers.

This is coupled by the presence of some rogue energy assessors that are more interested in money than quality, and may be too quick to sign off on the design.

Using info from the CSIRO, about 80 per cent of houses in 2016-2018 constructed in WA are finished using VURB or Non Accredited Energy Assessors. That means 20 per cent utilise the NatHERS pathway.

The verification utilising a reference building (VURB) compliance pathway was meant as a true alternative to the energy rating technique. It depends on the building of a reference building that has been modelled to adhere to the elemental “deemed to satisfy” provisions of the building code, with a design given the go ahead when theoretical energy use for the planned building is the same or lower than the benchmark energy heating/cooling loads of the reference building.

The issue is that it’s feasible to mock up a deliberately inefficient reference building that renders the planned design seem “better” by comparison.

In the 2019 update of the National Construction Code, the Australian Building Codes Board did away with these loopholes. The update was adopted by all states and territories in 2019 with the exception of WA, which lengthened the transition period to permit the previous version to be utilised until 1 May 2021.

Thoo remains worried that problem assessors are seeking other weaknesses in the system so builders won’t be prompted to enhance the thermal performance of their structures.

Others believe that performance solutions will replace VURB as a continuing loophole in WA to supply houses below the minimum 6 star standard.

A spokesperson of DMIRS, the agency who educates industry professionals on these issues, states the department is relaying new energy efficiency standards and rules to builders, developers and energy assessors.

The department is also looking at strategies to elevate public awareness and comprehension of this subject, so they will know that their home is fully and truly energy efficient.

The WA branch of the Urban Development Institute of Australia (UDIA), an industry group for the development industry, praises the impending update to the NCC that aims to accomplish improved energy efficiency in the building stock.

Source: The Fifth Estate