Louvre window for summer nights

Photo of an opened louvre window

The louvre opened

A daily chore in summer

My high-mass solar-passive house keeps me comfortable through the year with very little attention. I have detailed the actions I must take in this post. Being in BCA Climate Zone 4 “Hot dry summer, cool winter”, I have a summer regimen to keep the house cool, and a winter regimen to keep it warm. Most actions are required only twice a year: to change over from one regimen to the other. However, one action is required daily throughout the hot season: I must open doors each evening to admit cool air, then close them again in the morning. At night, air is drawn through the house and out the clearstory windows by the stack effect, assisted by fans at the windows. Warm air in the house is purged by the flow of cold night air, which continues to cool the mass of the house until sunrise.

My louvre vent project

[Photos, with descriptions, may be seen in carousel view here.]

Subsequently, I had to have the wooden louvre blades replaced with glass ones, as I describe in a later post.


I have put into effect a long-standing project to avoid the daily chore of opening and closing doors. I bought a motorized louvre window (Breezway Altair Powerlouvre Innoscreen) to let in the night air.

Photo of a programmable time clock

Louvre Time Clock

It is controlled by a programmable electric time clock (Hager EG203E) that will open the louvre at 21:00 and close it at 07:00 daily through the hot season. In the cold season the louvre will remain closed, with the motor control turned off.



The louvre closed

The louvre closed

The louvre is installed low in a wall on the colder south side of the house. It is near the back door that I have been opening and closing up to now. It was difficult to find a place to fit it.

I thought of fitting a motorized louvre in the back door itself. This would have been awkward and expensive. Doubly so, because the back door opens into the laundry, which forms an air-lock, and the inner laundry door would also have needed a motorized louvre.
The kitchen was the only suitable room to admit the cooling air. Of course, it is almost completely lined with benches and cupboards. Eventually, I found a place for the louvre, and had a hole cut in the wall for it.

Wall hole for a louvre

Louvre aperture from outdoors

Wall hole for louvre

Louvre aperture from indoors






The place I chose is partly behind the refrigerator.

Photo of louvre, cover panel, and fridge

Louvre behind fridge

That appliance, which gets warm as it cools the food, will get the first benefit of the in-flowing cool night air.
It may seem foolish to “waste” the cooling breeze on the refrigerator rather than directing it to the house and its occupants. I don’t think it matters: the refrigerator will be cooled one way or another. The louvre is only partly behind the refrigerator. It is partly behind a recess 220 mm wide that houses a curtain for closing off the kitchen from the dining room. In the cold season, the curtain will often be in its recess, adding to the insulation in the louvre area.


Photo of fridge and curtain

A curtain hides the louvre

In the hot season, the curtain can be looped back at the other end of its track (as can be seen in the photo “Louvre aperture from outdoors”).
I have reduced the barrier posed by the refrigerator by moving it 130 mm further out from the wall, and by raising it 80 mm on rails.





Louvre indoor view

Louvre indoor view

Wooden louvre cover panel

Louvre cover panel

The wooden louvre blades are in the plane of the cladding of the wall of the house. To add a second layer of insulation, I have had a wooden cover-panel made to slide into the gap in the inner wall-board. This panel will be in place only during the cold season, when the louvre is kept closed.


The louvre with its automatic control has been installed. I have learnt how to program the time clock, and to use the electronic over-ride system.
Unfortunately, the work, begun in the new year, was not completed before the weather turned cold.The louvre will not have to operate before November.

Subsequently, I had to have the wooden louvre blades replaced with glass ones, as I describe in a later post.

Monitoring performance

My daily reading of max/min thermometers will continue, with extra sensors indoors and outdoors near the louvre.
Details of changes in the daily cycle may show up when I do an occasional “blitz”, reading a number of thermometers about 15 times in each day.

NOTE: The uses of louvre windows

Louvre windows are popular in hot humid climates, where heat discomfort, due more to high humidity than to very high temperature, persists day and night. Louvres, which have a larger area of opening than other windows, freely admit breezes to cool people in the house.
Louvre windows have not been popular in my climate where summers are very hot and dry. Here, daytime breezes are too hot, and must be kept out. Louvres could be opened at night to let in cool air if they were fitted. They seldom were, because most louvres would not keep the house cool when they were closed. They conducted heat freely (high U-value), and leaked hot air in large amounts.

Recently, manufacturers have claimed that their louvres “…seal tightly to give the best performance possible…”. If that is true, then louvre windows can play a part in the design of low energy houses for places with hot dry summers. They can be opened automatically on summer nights to purge the house of hot air. At all other times they can be kept closed to seal the house against outside air that is too hot or too cold.

For use only for ventilation at night, louvres need not have transparent blades. Wooden ones provide more insulation than any kind of glass.

However,I found that the wooden louvres supplied were not satisfactory, and had to be replaced with glass ones, as I describe in a later post.

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