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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