Breeze Paths for Summer Cooling

As part of the concept design process it is important to know from whence your summer breezes blow, so that you can make sure your floorplan incorporates the openings in such a way that these potentially cooling breezes are encouraged to blow through the structure.  Local and historical knowledge of the area in summer is preferable, but failing that the Bureau of Metereology has created wind roses for its weather stations across Australia. 

Click through to your local site on the following map (www.bom.gov.au/climate/map/climate_avgs/clim_avg1.shtml), download the 3pm summer wind rose, and use it to mark up on your block which way the prevailing breeze blows.  Your floorplan and window layout should then, as much as possible, align to allow the prevailing breezes through the structure.  The basic rule of thumb is that the exit window should be 20% bigger than the entrance window, and the flow should be as straight as possible without intricate passageways to negotiate.  This works well in Melbourne that has regular summer sea breezes from the south, and where you want bigger windows to the north for thermal gain.  Casement windows can be very useful, as not only do they open 100%, but they can also placed on the sides of the house, hinged towards the prevailing breeze to scoop it in as it goes past.

Moving air can also give an approximate 3 degrees of cooling effect as it goes across the skin evaporating off the moisture.  So even if the breeze is the same air temperature outside and in, having good breeze paths through the house will be beneficial.  This is why ceiling fans are also so useful.

It is also worth checking if there are any summer night time prevailing breezes, as opening windows and bringing in the night air, will passively cool the house over the course of a summers night, ready to close windows the next morning ready for the next hot day. This ability to purge the heat is particularly vital for houses with higher thermal mass.

And on those still nights, cooling airflows can still be induced  by including clerestory or high windows, and popped ceilings.  See Clerestories.