The Pears Report: Summertime, and the living ain’t easy

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With summer approaching, there’s a flurry of activity to ensure reliable energy generation under peak loads.

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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.

 

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10 Comments
  1. juxx0r 1 year ago

    I did my own thermal balance to determine my heating and cooling needs. It was readily apparent that to improve the star rating i would have had to make the building worse. That is to improve it in summer would make it far worse in winter. That wasn’t a compromise that i was willing to make. So now i officially have a 7 star house that will perform like a 9 star house when operated correctly.

  2. Joe 1 year ago

    New housing estates with shiny new homes with black rooves sitting on a block with no green ‘soft’ yard area and all surrounded by black bitumen roads. Favourite game is…spot the tree. Just genius.

    • hugh spencer 1 year ago

      Sorry .. what is a “tree” .. curious, just asking

    • Colin Edwards 1 year ago

      It’s not just in new housing estates. In inner suburb Subiaco in WA, old two-bedroom houses are being replaced with black-roofed eave-less McMansions that cover most of the block..

  3. Rod 1 year ago

    Bemusement or incredulity.
    I can’t believe there are that many stupid people in the Country that think a black roof is a good idea. The 3 poorly built and badly orientated row houses next to me have black tin roofs and no sisalation under the roof. And they mounted their heat pump ac on the roof! Facepalm.

    • Ian 1 year ago

      Should be a law on architectural stupidity.
      Solar panels could provide some shading benefit in addition to the electricity…. Along with a mortgage paid off sooner by having solar pv.
      When will we have government for the people?

      • Rod 1 year ago

        Not sure you can blame Architects. Most of these dwellings would have the colours and other finishes decided by the builder/developer. The owner (assuming they are involved from the start) should be calling the shots.

        Agree re the shading value of PV. When we installed our second array (which along with a Solar HWS covers most of our North roof) we noticed a drop in heat entering the building in Summer. Maybe that is the answer. More solar panels 😉

  4. Les Johnston 1 year ago

    Why is the black roof eve-less syndrome dominant in Australia? Air conditioning cooling loads calculations have not changed in 50 years. Why did the fake claims of the energy rating system not be revealed? Just like the halogen downlight, the sooner the fad is buried, the carbon footprint will be reduced. There is hope.

  5. George Darroch 1 year ago

    More people die in the Australian winter from cold, however.

    We need far better insulation for both seasons, and we need it now. It’s not good enough. Some of us shivver, and some of us die.

  6. solarguy 1 year ago

    We have been building energy inefficient shit boxes in this country for way to long. Changes to the National Building Code need to be made very soon!

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