CSR House Keeps Its Cool On Hottest Day On Record

Scott Clarkson, Project Manager, CSR Innovation discusses how the House’s new data will influence Australian construction trends

Planning and building any house requires seemingly endless drawing, designing and sourcing materials before any construction actually starts.

So it’s no surprise building a state-of-the-art 8-Star house, like CSR House in Western Sydney, required such an enormous amount of research, planning and analysis to ensure that all the energy and sustainability outcomes were achieved in a cost-effective manner.

"The challenge we faced was not insignificant," says Scott Clarkson, CSR’s Project Manager – Innovation.

"We had to figure out a way to make 7-Star and 8-Star housing affordable and accessible to the mainstream market. From start to finish, we knew that all of our calculations of cost versus performance would come under intense scrutiny and would need to be reproduced for the mainstream market."


The heating and cooling performance of CSR House, including its thermal stability, is indeed impressive. During testing conducted on a cold winter morning in June 2012, the internal temperature of the house never dropped below 16 degrees, despite the fact that the outside temperature was 1.2 degrees and the heating had been turned off for almost a month. A number of factors were found to have contributed:

  • Connectivity to the concrete slab: To help maintain a stable temperature, the interior of the house is coupled to the concrete with floor tiling on the lower level, and an internal skin of face bricks in a feature wall. As a result, the slab temperature throughout winter remained stable at or around 17 degrees.
  • High levels of insulation and Low e double glazing cut heat loss through conduction and radiant heat gain in summer.
  • Air control and controllable ventilation help prevent cold air leaking into the house. Quality construction techniques encourage natural ventilation while maintaining internal thermal comfort.
  • Passive solar design allows the house to trap radiant heat from the sun during the winter months, providing natural “free” heating that is absorbed into the internal thermal mass.

Conversely, in summer when the outside temperature topped 40 degrees Celsius the internal temperature remained steady at around 27 degrees, without air conditioning.

When The Mercury Hit 45 Degrees Celsius, The Interior Of CSR House Remained 15 To 16 Degrees Cooler Than The Outside Temperature

Even on Sydney’s hottest day on record - January 18, 2013 - when the mercury hit 45 degrees Celsius, the interior of CSR House remained 15 to 16 degrees cooler than the outside temperature. When the ceiling fan cooling effect (or physiological cooling) is factored in, the “feels like” temperature was approximately 26 degrees.

NOTE: The above data was collected when the CSR House was operating in “Free Running” mode, i.e. with NO heating or cooling systems operating.

Further research

CSR is continuing to collect data from CSR House. Further findings will be discussed in future editions of Building Knowledge, including:

  • A comparison of the thermal heat flow (bridging) performance of a 90 x 45mm timber stud, in comparison with a 90mm light gauge steel stud and R 2.7 insulation
  • A review of the seasonal soil temperature and moisture variations below ground (0.5 m and 1.0 m deep) at various locations around the house
  • What does comfort really mean? Is it just temperature and humidity, or do other factors come into play? We look at acoustics, radiant heat, natural light and air quality
  • How much energy is actually required throughout the year to keep the CSR House within the comfort zone?
  • What do government workers, PhD students, school children and building designers have in common?
  • The four keys to reducing energy use in your home, office or workshop

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