One of the major determinants of a homes ability to maintain a temperature is its air tightness. We all know about opening our windows at night during summer and closing them in the morning.
What happens during winter?
What about winter where we want to stop cold draughts?
A well built home, with windows and doors that are properly sealed reduces the amount of air leaving or entering your home during the times you want it to maintain a temperature. That’s why we blower door test our homes to ensure that it seals correctly.
What is a blower door Test?
The house is either pressurised or setup as a vacuum using a fan unit with all the windows, doors and vents closed.
The fan then measures the volume change between the inside and outside are to ascertain a qauntity of air changes per hour.
It’s such an important issue the CSIRO studied homes all over Australia to find out just how well (and how poorly they performed). Below are some notes from the report we thought you might be interested in.
They Discovered
The National Average Air Changes per Hour is 17.7
The Average in Adelaide is 8.5!
CSIRO report extract:page 13:It is interesting to note that some of the houses tested used uPVC window frames.
These frames usually have built‐in sealing systems to provide a tight seal between the window frame and the house frame.
Houses with aluminium or timber frames were found to have a broad range of results, but apart from one outlier, houses with uPVC window frames recorded much lower air change rates than most other houses.
Page 40:Houses with aluminium or timber frames have a broad range of results while houses with uPVC window frames recorded much lower air change rates than most other houses.
Here is a general comment about the quality of build, which is noted as higher for architect designed homes (page 13):Adelaide and Hobart houses recorded results significantly lower than all of the other cities tested.
On average, Adelaide and Hobart houses had an ACH@50Pa of 8.5 and 7.9 respectively, whereas the next closest average was for Canberra at 14.1 ACH@50Pa.
The reason for this significant difference was not clear and additional investigation and data analysis was undertaken of the Adelaide houses as a case study to try and determine a factor or factors that may be responsible.
Building materials and practices were investigated and discussions had with builders,
The reason for this significant difference was not clear and additional investigation and data analysis was undertaken of the Adelaide houses as a case study to try and determine a factor or factors that may be responsible.
Building materials and practices were investigated and discussions had with builders, architects and developers.
Overall no specific differences from common building practice could be identified, but a higher than usual proportion of architect and custom designed houses in both the Adelaide and Hobart cohort lead to the conclusion that greater attention to build quality had occurred and this had resulted in better than average test results.
