The ABCB has released proposed energy efficiency changes to be included in the National Construction Code 2022.
The plan is for Class 1 and 2 buildings to increase from 6 stars to 7 stars, under the NATHERS rating scheme. This is despite the fact that the government’s own numbers show that the costs considerably outweigh the benefits; the net cost in Queensland would be about $201.9 million per annum.
Builders who have sought to apply the new requirements on their own projects are reporting price increases in the order of $20,000 per house.
Since 2010, the Queensland Development Code (QDC) has allowed optional credits for an outdoor living area/ ceiling fan and photovoltaic solar to meet the 6 star energy efficiency requirement. The QDC also provides reduced glazing requirements and an exemption for insulation under suspended floors in climate zones 1 and 2.
The Queensland Government, in seeking to deliver on their commitment to net zero emissions, they have committed to moving up to 7 stars and removing the QDC nominal credits and exemptions for glazing and suspended floor.
The proposed changes are based on assumption that a house is a “closed box” to be air-conditioned.
In Queensland, we are concerned that these new rules will force designers, architects and builders to move away from designs that connect to the outside (a key feature of most Queensland homes) and in doing so force those building or buying new homes to incur the unreasonable cost of double glazed and tinted glass windows. There will also be increased insulation requirements requiring some homes to expand the wall stud width from 90 mm to 140 mm, reducing the useable area of the house and increasing the cost to build.
The new regulations will lead to requirements for the sub-floor on platform houses (Queenslanders) to be enclosed and/or insulated. Queenslanders are built to allow cross ventilation to cool the house overnight. Enclosing and insulating the subfloor prevents this and can also cause condensation issues and degradation of the subfloor structure. It will also leave these houses less resilient to flooding.
Increased requirements for eave overhangs will prevent many two-storey dwellings being sited on small lots with a knock effect on land affordability.
The new requirements will also limit consumer choice by restricting building design layouts and imposing restrictions on wall and roof colours across Queensland’s climate zones.
In summary, adopting the narrow “closed box” approach will add costs without maximising the opportunity to reduce emissions and have a detrimental effect on traditional Queensland designs.
There are better ways to achieve more energy efficient houses and keep the desirable elements of designs that are quintessentially suited to our climate in Queensland. These can include:
- Maximising good passive design. A house that is well ventilated, appropriately shaded and orientated correctly will be more comfortable without needing to resort to extensive insulation, double glazing or air-conditioning. Having access to a block rating tool for residential developments will improve the interaction between the land development and building design and better enable good passive design.
- Empowering homeowners to make decisions on investments in renewable stored power (PV and batteries) to build a home that is not dependent on energy from the grid. A whole-of-house rating tool will help serve this purpose and is expected to be available for all climate zones by 2025.
These options should be explored and the energy efficiency changes delayed until NCC 2025 so they can be done right.
Energy saving and emissions reduction are essential as we progress towards a zero carbon future. The answer, however, is not increasing the building shell by requiring extra insulation and tinted or double glazing. The goal can be meet by many different paths and our challenge now is to find the way forward that will result in liveable, affordable homes for all Queenslanders.
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