A hot roof heats up the inside of the house or building.

Think of your roof as a stove top or frypan with you in the pan or pot above the gas flame or heat source.  For the building the heat source is the sun.

To cool your house you can cool your roof.

A question just into my email reminded me of the roof as frypan and this is the houseowner’s problem:

‘Hello Michael

I am hoping that you can advise me of the beats way to address the removal of heat from the roof cavity of my two storey terrace house. In summer the upstairs area gets extremely hot and we end up running fans and ceiling fans in  the night. I am looking to reduce the heat build up in the ceiling cavity as well as increasing the flow of air in the house.

I have looked at various options for the removal of hot air in the roof cavity and lacking any knowledge of the various models I am seeking your opinion. The basic whirly gig versus solar operated systems ???

Re air flow we were thinking to place a skylight with an opening window upstairs thinking that this may increase the flow of air in the house.

My home is free standing on one side which receives all the afternoon heat. I was looking at adding either canvas or wooden window awnings to the windows on  that side of the house.

What is your opinion?? Any other suggestions?

Thanks

Anonymous”

Options include:

Cool roof:

• Pale roofing designed to cool a building: eg  http://sustainability.bluescopesteel.com.au/cool-roofs

Cool roof paint:

•  Paint designed to reflect heat; some paints are clear and can go over dark roofing such as red and green tiles and other paints have pale colours; eg  http://www.dulux.com.au/specifier/our-brands/dulux-acratex/infracool

Exhaust fans:

• A wide range of fans are available from many suppliers; some are powered by electricity (which can be solar powered), some are turned by the wind itself;  eg  http://www.edmonds.com.au/Products/Residential/Sub-Floor-Ventilation/ecoFAN.aspx

Insulation:

• A range of insulation products go below the roof; they can be pink batts (I rarely use these as they lose efficiency, take up too much room, and don’t work well in winter); reflective, insulated materials – of these the one I think is outstanding  due to its thinness, high efficiency, and capacity to cool the building in summer and to keep it warm in winter is this product: Polyair Performa - http://www.reflectiveinsulation.com.au/

The area around your building will usually cause the temperature around your building to be 2 to 6 degrees hotter than it need be; black roads, no trees and dark roofs heat our cities up – for an explanation and solutions see my book, Sustainable Food, or another blog here.

There are other ways to cool your house and they’re listed in my other book, Sustainable House.

The most cost effective way to cool the side of a building is to grow plants about 150 to 250 cm off the side of it.

If you can get a constant stream of air rising from the bottom to the top of the house or through it the moving air will cool your flesh; this only works if the outside air is cooler than the inside air.  That’s why our cities will only stay liveable, and will get cooler, if we build cool roads with pale road materials and plant cooling trees in them; for an example of a pop up cool median strip see the blog about ecopops where pop up garden designed to go in the middle of a road, car park or beside a dark surface to cool it can drop temperatures there by a couple of degrees the moment they’re installed.

Good luck,

Michael