Are Australian houses built for extreme cold?

Much of southeastern Australia is experiencing one of the coldest starts to winter in decades, with maximum temperatures in several cities remaining below 15C since early June. With many Australians raising their thermostats, there has been a corresponding increase in demand for electricity, leading to an energy supply crisis.

So, are Australian homes built to withstand extreme cold? Not exactly! Adrian Barnett, associate professor of public health at the Queensland University of Technology, described Australian homes as ‘glorified tents’ when he explained why more Australians died from the cold rather than the heat for which the country is known.

“Perhaps the poor insulation in our cooler-climate homes is a result of being on a hot-weather-dominated continent, where airflow and large windows make sense,” says Dr. Chris Jensen , Lecturer in Construction Management at the Melbourne School of Design, Faculty of Architecture, Construction and Urban Planning, University of Melbourne.

Australia was quite behind the regulatory game when it came to the design and construction of energy-efficient homes. The National Home Energy Rating System, also known as NatHERS, which measures a home’s energy efficiency, was first introduced in 1993 and adopted nationwide in 2003. houses and apartments are rated and rated from 0 to 10 stars based on energy performance, where a 0 star rating means that the building envelope does virtually nothing to provide protection from heat or cold, while a home rated 10 stars may not need artificial cooling or heating all year round.

Since 2011, new homes across Australia have required a minimum performance of 6 stars to comply with National Construction Code (NCC) energy efficiency requirements.

However, a study conducted for the Australian Greenhouse Office in 2005 found that Australia’s minimum 5-star standards were actually about 2 stars below equivalent standards in the UK, US and Canada.

Worse still, a significant part of Australia’s building stock is old, built before the introduction of minimum energy efficiency requirements. These homes typically have single-glazed windows, leaky building envelopes with poor airtightness, and minimal wall and roof insulation, all of which contribute to reduced energy performance and higher energy bills. high.

The average Australian home has a 1.8 star rating, meaning it takes a lot more energy to heat or cool the home compared to a 6 star or 10 star home. How much more? The annual energy consumption of a 200m² 2-star house in Melbourne would be around $4964, while a 6-star house of the same size would see an annual bill of $1474 and a 10-star house barely $26.

High energy costs also lead to ‘energy poverty’, particularly among vulnerable sections of the Australian population, with one in four households reducing their energy consumption, especially during hot summers and cold winters. A UNSW study of low-income households in New South Wales, covering 100 social housing units in the Greater Sydney area, found that the minimum indoor air temperature was around 5°C in winter (2018) and the maximum indoor air temperature was 39.8°C in summer (2019).

With open plans and large windows to allow cool air circulation and cross ventilation, Australian homes are designed to embrace the warm, sunny weather. The same characteristics impact the energy performance of the house during the cold season.

In addition, 80% of all new homes are designed and built only to the minimum 6-star requirement, which means that these buildings cannot provide the energy performance required to ensure thermal comfort for residents throughout the life of the building. ‘year.

So what is the solution ?

For existing homes, especially those built before 2003, a complete renovation is recommended to prevent heat loss and create an airtight building envelope. Remedies include sealing gaps around windows and doors; sealing ducts; and wall, roof and basement insulation. Solutions that would require significant investment include replacing existing heating and cooling systems with more efficient units; and replacing single-glazed windows with double- or triple-glazed units.

Additionally, increasing the minimum energy efficiency requirement from the current 6 stars would ensure that new homes will provide occupants with superior energy performance and year-round thermal comfort. However, homeowners should talk to their architects and builders about building their homes to deliver superior energy performance rather than agreeing to mandatory minimum requirements.

“The principles of passive design and construction work both ways – by making your home better insulated to keep heat in during the winter, you are also making it more efficient at keeping cool in the summer, especially if exertion is made to better shade windows and other glazed surfaces,” says Dr. Jensen.

Picture: istockphoto.com

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