CSIRO: Australian homes performing better than ever

New research from the CSIRO has revealed new Australian homes are up to 50 per cent more airtight than those tested in 2015. 

The CSIRO says this is good news for homeowners, as houses and apartments that meet recommended airtightness levels are more comfortable, cheaper to heat and cool, and could also have healthier indoor air quality if the right ventilation system is in place. 

Airtightness minimises unintended air movements within a building, preventing outdoor air from entering and indoor air from escaping.  

Poor airtightness can cause draughts, increasing energy bills by up to 20 per cent. Conversely, homes that are too airtight without controlled ventilation can lead to condensation, mould and health issues for residents such as headaches and nausea from higher carbon dioxide and monoxide levels.

The test

Researchers tested a total of 233 apartments and detached houses built in the last four years in Melbourne, Sydney Canberra, Brisbane and Adelaide. Homes specially designed for airtightness were excluded. 

While the research results were positive and compare well to standards in other countries like the UK, the study found room for improvement. 

Senior experimental scientist and project lead Michael Ambrose says the research used a blower door test to identify the leakage rate and determine where leakages occur.  

“Leakages were found in most new homes, mainly from bathroom fans, sliding doors and poor or missing door seals,” Ambrose says. 

“Some other homes, particularly apartments, were found to be extremely airtight, which can result in issues impacting building performance and resident health, if controlled ventilation is not included. 

“Fortunately, there are simple and affordable ways to rectify these issues and preventative measures that can be implemented during construction.”

Recommendations

The report outlines a range of recommendations for Australian building codes to address common airtightness issues, including: 

• establishing airtightness standards in the National Construction Code (NCC)  
• requiring controlled ventilation in new buildings – particularly apartments – to reduce indoor pollutants and moisture 
• making air barriers such as building wraps mandatory in all new residences  
• providing on-site training and educational resources to connect builders with cost-effective solutions that improve building performance.

The study, funded by the Department of Climate Change, Energy, the Environment and Water found that actual airtightness levels were closely aligned with those assumed by the Nationwide House Energy Rating Scheme (NatHERS), which provides an energy efficiency star rating for residential buildings. 

“This provides us with strong confidence that NatHERS is accurately predicting airtightness within specified levels,” Ambrose says. 

“We see value in displaying airtightness values on NatHERS certificates and noting the impact on the star rating. 

“But overall, our research found that new Australian homes are performing better than ever before.”

Catch it at HVAC24

Ambrose will present the team’s findings at AIRAH’s 2024 HVAC Innovation Conference (HVAC24), which will be held at Hotel Grand Chancellor Brisbane from 12–13 September. His presentation – “Air tightness of new Australian dwellings” – will take place at 11am on the first day of the conference.

You can register for the conference via the HVAC24 website.