Ventilation louvre hassles

I specified wooden louvre blades

This louvre window installation is described in this earlier post.

Photo of louvre for night purge

Louvre now fitted with glass blades

The automated louvre window that I specified for my system of summer cooling by nocturnal purge had wooden louvre blades of western red cedar 14 mm thick.
I specified wood because I preferred that this louvre should not be transparent, as I did not want to see through it and I did not want it to admit light. I took the risk that wooden blades might not seal as well as advertised.
Other posters on the ATA forum (see link below) doubted that the blades would seal effectively. They were right.

Failure of the wooden blades to seal

When the louvres were closed for the first time, there was clearly no seal at all. The rubber seals fastened to the blades failed to meet the matching blades, leaving gaps of up to 2 mm admitting daylight.

Attempts to rectify

I wrote a letter of complaint on 18/5/2016.
Rectification work on warranty first revealed faults in the gallery of gearing at the side of the window. However, when the gallery was replaced the gaps remained. The photo shows daylight visible on the right side through three of the gaps.

Photo evidence that louvre does not seal

Wooden louvres showing daylight

As the blades did not meet their specification, the company replaced them without charge. When these new blades did not seal any better, the company offered (on 10/10/2016) to replace them with aluminium blades, 6 mm thick. I reviewed the specifications of their blade options, and decided that this was not acceptable. The aluminium blades had little thermal resistance (U-value: 6.55). Glass blades 6 mm thick, with a low-e coating had much higher thermal resistance (U-value: 4.40), almost the same as the wooden blades (U-value: 4.39). The company agreed to provide these low-e glass blades. (In fact, this had been their original suggestion.)

Sealing of glass louvre blade gaps

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My Heat-control Courtyard

Photo of a small courtyard

A Heat-control Courtyard

I have added a courtyard to my high-mass solar-passive house to improve summer cooling and winter heating.

Photo of building materials

Courtyard Wall Panels and Gates

The courtyard extends 13 metres along the south wall of the house. It is completely enclosed by a wall of white-painted polystyrene sandwich panels 1.8 metres high, with two gates of the same material.

By September 2015 trenches had been dug for the courtyard foundation, and by December it was complete.

Photo of trenches dug for courtyard

Courtyard Trenches, West

Photo of trenches dug for courtyard

Courtyard Trenches, East

Operation

This house is in BCA Climate Zone 4: Hot dry summer, cool winter. For comfort, it must be made very much cooler in summer and very much warmer in winter. The courtyard was built to help to achieve both results without the use of heaters or coolers.
In summer, it should ensure a supply of very cool air at night. In this house, cool air is drawn in to replace warm air that flows out the clear-story windows by the stack effect, assisted by fans. By day, the courtyard walls also block some solar radiation.

Photo of courtyard from the west

The Courtyard Through The Western Gate

In winter, the white courtyard wall reflects sunshine north towards the house, and re-radiates heat lost from the house wall back towards it.

More

Much more detail is given in the page “A Heat-control Courtyard”. All photos on this topic are in a gallery in “House Photos – 2016”.

New Post on Wicket Gates

In August 2017 I added a new post about wicket gates that were added to the solid gates in the courtyard gateways.


To invite discussion of how courtyards can affect indoor and outdoor climate of houses, I opened a thread “Courtyards for Climate Control” on the forum of the Alternative Technology Association (ATA) based in Melbourne.

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.]

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

Installation

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. Continue reading

Managing my low-energy house: II. Features needing attention

Photo of clear-story area with winter sun and a fan

Clear-story fan set for winter

This post, and the companion post I. Features needing no attention were posted originally to a forum of the Alternative Technology Association (See Note below.)

My low-energy house at Manilla, NSW, maintains year-round comfort in a climate of daily and seasonal extremes. In the climate classification of the Building Code of Australia, it is in Zone 4: “Hot dry summer, cool winter”, along with Tamworth, Mildura and Kalgoorlie.
This house differs from most houses in relying on the design of the house to achieve comfort, with hardly any energy needed for heaters or coolers.
There is little artificial control: the “home automation system” consists only of timers set twice a year. Some of the comfort features call for daily action in certain seasons. However, these simple daily chores could have been avoided by small changes in the design. [But see “Note added 2016.”]

The success of the house in maintaining comfort in all seasons is shown by scatter-plots of daily indoor and outdoor maximum and minimum temperatures over a period of three years.

Features re-set twice a year

Dates for re-sets

For part of each year, the Manilla climate is too hot for comfort, and for the rest it is too cold. Some house features are re-set twice a year, making a “winter regimen” and a “summer regimen”. At first, I set the change-over dates near the equinoxes, 20th March and 22nd September. For simplicity I changed on 1st April and on 1st October. Later, I found it better to change on 1st March and 1st November, because the time when the climate is too hot is shorter than the time when it is too cold.

Motorized curtains

Curtains fitted to five north-facing windows, and a shutter fitted to a sun-porch window, should be opened to admit winter sun and closed at night to trap the heat. In summer they should be closed by day to keep out radiant heat and opened at night to allow heat to radiate out. The curtains and the shutter have motors controlled by a programmable timer (at lower right in the photo). In autumn (1st March), the timer is set to open at 07:40 and close at 17:20 daily. In spring (1st November) the timer is set to open at 18:00 and close at 06:00 (Standard Time).

Clear-story windows and fans

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