Yeah and no eaves on a lot of them. It is ridiculous, there should be a law to prevent dark roofs, and make new houses have eaves and a rainwater tank.
But the pollies would rather put up the cost of power and water whilst whinging we use too much

It's absolutely mindboggling, I just can't figure it out.
It's such a basic, obvious factor. You only have to have owned a light and dark coloured car to know the difference.
A friend of my wife's had her dark roof replaced with a light one late last year, she says the use of their airconditioner has dropped considerably since.

There was a letter to the editor of our local rag, some idiot reckoned a black roof made sense in Perth because heating bills out weighed cooling. What he didn't consider is a black roof also radiates the heat away at night.

It makes a lot more sense, to have a light roof well insulated, and get winter sun thru North facing windows with enough overhang so summer sun doesn't get in. Combined with flow thru ventilation so the seabreeze and easterly can cool the place at night.

whirlybirds are the answer to getting heat out of loft.

insulation can make a house warmer in summer if house has a large window facing the sun.

If you remove the trees that cool the earth and replace them BLACK roads that get very hot at times.... so maybe its the BLACK roads that have been some of the cause of global warming?...

It is covered by law now. Vol 2 of the BCA part 3 is quite specific about the insulation value required for a roof. Its fairly recent stuff though.

You can still have your black roof but the overall insulation must comply with a prescribed minimum.

good to hear the words of the wise.

computer models calculate heat gain and loss these days and colour of roof is taken into account. it's a system that needs to be looked at.

NotWal said...

It is covered by law now. Vol 2 of the BCA part 3 is quite specific about the insulation value required for a roof. Its fairly recent stuff though.

You can still have your black roof but the overall insulation must comply with a prescribed minimum.

Yep kind of a messed up country we are in. In Queensland it is actually against the law to leave your car if the window is wound down more than 5cm. Yet you dont have to have double glazing, eaves, insulated roof and as you say; can have a black roof! I think we should all be allowed to live in tree houses and wear sarongs in public... (ok, part of that post is serious, part is me enjoying the end of the day)

OK I'll bite. Why would you want a black roof? (a part of the house that most people living in the house hardly ever see anyway)

Gestalt said...

hi herry,

>>>>
i think the idea of light colours and large overhangs is over rated. it's such a small part of things and in the end will leave you with a building that potentially is very cool but will freeze you in winter.
>>>>>

This is crap gesty! it's a simple matter of getting the angle of the house right. Minimising east and west windows, to stop summer sun, getting the overhang right for the north facing windows, and you have 0 sun heating in summer and plenty of sun heating in winter.
Agreed if the overhang is too large you loose winter warming, but that is only on the North faces. East and West should be huge if there are big windows. Or external shutters, internals don't do anywahere near as good a job at reducing heat intake.
This house, is around 10deg cooler than outside in summer, and 10 - 15 deg warmer than outside in winter.
apart from the sun and the seabreeze, the only form of heating, is what comes from ordinary kitchen appliances,
the only cooling overhead fans.
People vistiting often comment how warm it is in winter, & how cool it is in summer.

whats crap, the idea that light colours and large overhangs are over rated.

or the idea that large overhangs and light roof will keep a houses temp down and help make it an ice box in winter?

i have a house, with no overhangs, no awnings, full height eastern glass, a black roof and it works better than any other house in the street.

unlike all of the other houses i don't have ac or heaters and don't need them but my house apparently breaks all of the rules.

why does it work,

good cross ventilation, orientation, lightweight upstairs hi mass downstairs and curtains.

decrepit said...

Gestalt said...

hi herry,

>>>>
i think the idea of light colours and large overhangs is over rated. it's such a small part of things and in the end will leave you with a building that potentially is very cool but will freeze you in winter.
>>>>>

This is crap gesty! it's a simple matter of getting the angle of the house right. Minimising east and west windows, to stop summer sun, getting the overhang right for the north facing windows, and you have 0 sun heating in summer and plenty of sun heating in winter.
Agreed if the overhang is too large you loose winter warming, but that is only on the North faces. East and West should be huge if there are big windows. Or external shutters, internals don't do anywahere near as good a job at reducing heat intake.
This house, is around 10deg cooler than outside in summer, and 10 - 15 deg warmer than outside in winter.
apart from the sun and the seabreeze, the only form of heating, is what comes from ordinary kitchen appliances,
the only cooling overhead fans.
People vistiting often comment how warm it is in winter, & how cool it is in summer.

cisco said...

Herry said...
We have a 2000L rainwater tank that is plumbed through to our toilets and washing machine.

Why would you do that?? I would use a quality filter for that water and drink it and use the government supplied water for flushing and washing.

Haha!! that's exactly what we do! Unfortunately at this time of the year we have to switch back to mains, you can really tell the difference! Rain water tastes great!

ok, feel free to drink all of the pollution in the first 20lt or so of water out of your gutters.

Gestalt said...

ok, feel free to drink all of the pollution in the first 20lt or so of water out of your gutters.

It would actually come out of the tank not the gutters and for the end of long dry spells there are diverters to manage the initial pollutants.

Gestalt said...

you mean like a FIRST FLUSH SYSTEM!

that's free thinking for you.

Well I am sorry for not being up to date with the latest trade jargon. What is a stud?? Animal vegetable or mineral?? Could be all of the above. Think about it.

Touche I believe.

brucey65........Your 1st answer is correct but your 2nd answer is a load of BS & i would be very interested to find out where u got your facts from .. PLEASE EXPLAIN ?

ok ,i will have a go.

i do believe insulation[in summer] can in a few rare cases can make a house warmer.

20/25 years ago i got into a arguement with my dad over this subject.

a few years later,i read somewhere, think it was in readers digest of experiment to see just how effective insulation was at helping to keep a house cool.

to my surprise, i was partly correct.

finding was insulation is effective at reducing heat in house.

however, in house with many large windows exposed to sunlight, the finding was the house can become warmer with insulation fitted!

heat enters easily thru window and is trapped by insulation in loft from escaping.

makes sense to me.

a greenhouse with insulation fitted to roof could possibly make greenhouse warmer.[if greenhouse had a tiled roof]

for the vast majority of houses, 99 plus percent, i agree insulation is effective.

i do believe whirlybirds are a cheap, effective way of reducing heat by around a couple of degrees in summer.

was in a loft once in summer, i opened up a few tiles and temp in loft dropped maybe 5 to 10 degree centigrade.

this opened my eyes to how effective whirlybirds can be.

not too sure about winter though.