New homes which are built throughout Australia will need to meet 7-star energy efficiency standards if proposed changes to the nation’s building code are adopted.

And household equipment such as air-conditioning, hot water systems, lighting and swimming pool and spa pumps will need to meet an overall ‘budget’ in terms of energy consumption.

The Australian Building Codes Board has released the second and final stage of its public comment draft for the 2022 edition of the National Construction Code (NCC 2022).

(Released in May, the first stage quantified a range of performance requirements and outlined new requirements for accessible housing, egress in childcare centres and primary schools, bushfire protection and lead levels in plumbing products.)

The most important change in the second stage involves new provisions which will ensure that homes and apartments which are constructed under NCC 2022 or later met new and more stringent performance requirements relating to energy efficiency.

Whilst amendments to performance requirements to reflect this were included in the first stage of consultation, the second stage features detailed changes to deemed-to-satisfy provisions. These aim to ensure that homes which are constructed using DTS provisions actually deliver upon the new and more stringent performance requirements which were included in the first stage of the consultation.

In terms of the building’s fabric, the DTS provisions have been updated to ensure that any new homes or apartments which are constructed under DTS provisions meet an energy performance level which is equivalent to 7 stars under the NatHERS energy rating system.

This represents a one-star increase when compared with the previous situation where dwellings were only required to achieve 6-star heating and cooling load limits.

In addition, the new version of the Code will also adopt a holistic approach in relation to the energy performance of key household appliances such as air-conditioning, hot water systems, lighting and swimming pool and spa pumps.

In the case of Class 1 buildings (detached homes and units), this budget is based on a level of stringency which is equivalent to 70 percent of the annual energy use of the following benchmark appliances:

• a 4.5-star heat pump for heating and cooling, rated under the 2012 Greenhouse and Energy Minimum Standards (GEMS) determination
• a 5-star instantaneous gas water heater, rated under the 2017 GEMS determination; and
• a lighting power density of 4 W/m2.

According to the ABCB, this approach is considered to be holistic in nature as well as being flexible as it enables trading between the efficiency of various pieces of equipment to achieve an overall energy use budget across the equipment as a whole.

For the purpose of meeting this budget, the new rules will enable any energy which is generated through on-site renewables to be offset against that which is generated by the equipment.

In the case of sole occupancy units in Class 2 buildings (apartments) and Class 4 parts of buildings, a lower level of stringency will be applied.

For these buildings, the budget will be based on a benchmark of 100 percent of the energy usage of the benchmark appliances referred to above.

According to the ABCB, this lower level of stringency which will be applied to Class 2 and Class 4 buildings is appropriate in light of the difficulty associated with installing on-site renewable energy systems on these buildings.

If accepted, the above changes will represent the first stringency increase for residential buildings under the Code since 2010.

The changes are also in line with the Trajectory for Low Energy Buildings agreed to by energy ministers in 2019.

This trajectory aims to set a long-term pathway toward zero carbon buildings in Australia.

As part of that agreement, ministers determined that a stringency increase would be applied to commercial buildings in the 2019 update of the Code and to residential buildings in the 2022 update.

Other amendments which are contained in the final stage of the public comment draft include:

• a new set of Deemed-to-Satisfy elemental provisions for Class 2 buildings
• new provisions designed to allow easy retrofit of on-site renewables and electric vehicle charging equipment for Class 2 to 9 buildings, and
• enhanced condensation management provisions, including additional ventilation and wall vapour permeability requirements.

Green building lobby groups welcomed the changes.

“More energy efficient houses provide a win-win-win opportunity in terms of jobs, energy savings and emission reduction and are essential as we progress towards a zero-carbon future,” Australian Sustainable Built Environment Council President, Professor Ken Maher AO said.

“Australia’s homeowners and tenants need certainty that they are gaining the health, comfort, efficiency and environmental benefits that they could reasonably expect.”