Those who have watched in bemusement the large numbers of new homes with black roofs and no eaves might be interested in some recent research.
This research has found that our 6 Star regulations are doing a good job of reducing winter heating energy use. But the way some designers use the rating tools may be making summer performance worse.
Basically, it’s possible in most locations to meet the 6 Star regulations with measures that improve winter performance. But this means homes can still let in summer sun and their improved insulation means they can behave like solar ovens, cooking their occupants.
This can be relatively easily fixed by installing effective summer shading and also looking at orientation and areas of glazing.
Summer overheating is not benign. Analysis of outcomes during the very hot week preceding Melbourne’s 2009 Black Saturday fires showed that, just as extreme hot weather drives big peaks in cooling energy demand, it causes other peaks, too (see here).
Twice as many people died from the heat in the days leading up to the fires as died in the fires. 374 people died, 62% more than in the same period the year before, many of them elderly.
Pressures on health services peaked. There was a 46% increase in ambulance callouts, with a 34-fold increase in heat-related conditions. Hospital emergency departments saw a 12% increase in demand, with an eight- fold increase in heat-related problems. There was almost a three-fold increase in patients dead on arrival.
RMIT research (a 2016 PhD by Niki Willand based on detailed analysis of a CSIRO eld study), found the analysed 5 and 6 Star-rated homes were hotter than 4 Star ones on average, and had higher cooling energy use.
This is due to the ‘solar oven’ effect. A 6 Star house can be designed to work well all year round, but winter performance dominates the rating rules.
None of the costs and human impacts of these statistics have been factored into national building code considerations. Indeed, it seems there will be no major changes to the regulations until at least 2022.
There is a glimmer of hope, though. The Victorian government’s new apartment planning guidelines include reasonably strong summer cooling energy limits (see www.bit. ly/VGAPG17) as well as the annual energy limits. These will force designers of apartment buildings to rethink their approach. Let’s hope this spreads to all new homes.
Source: This was first published in ReNew (Alternative Technology Association). Reproduced with permission of the author.
