Monday, 11 July 2011

Windows going in

They were starting to load the windows from their storage half an hour away in Hotaka at 8:30 and supposed to arrive at the site around 10. Kentaro from Wuerth turned up around 10:30 to show them how to use the compriband.

I heard the crane go past my house at 8.30. Presumably they can only hire cranes for whole days. Crane drivers must be used to sitting in the cabs for hours waiting for something to happen. Perhaps a career worth considering, although it may be a bit late for me to switch.

The windows started arriving after 11:30, which did not surprise me. Kentaro had another appointment later, so could only comfortably stay till 12:00. In the end he stayed a bit longer and showed them how to install the compriband around one of the smaller windows. He reassured me later that he made his next appointment on time. It's a shame that most of the time he was here was spent waiting and listening to my rants on energy efficiency and its enemies in the Japanse building industry, rather than watching and advising on the application of his product.

As of the morning, nobody seemed to know how the large fixed upstairs windows were going to be installed. The fixed windows are triply tricky because they are going upstairs, they are heavy because the glass cannot be removed from them, and they cannot be fixed to the pillars in the same way as the other windows, from inside the frame.  The moving windows can be taken out of the frames and screws put through the frame into the pillars on each side. Small strips of wood and a crowbar are used to adjust the windows when they are installed, and a spirit level to check they are horizontal and vertical. This makes a big difference to windows that swing open, and in the case of the concertina door, another adjustment is needed for each wing of the window. Yesterday I spoke over the telephone to  the manager of Pazen, the German manufacturers. He plans to be in Japan in September and offered to make final adjustments then.  

In the case of the fixed windows, obviously the glass cannot be opened and removed, so the frames must be fixed from the outside. As this is impossible, or at least very difficult with the wall construction and 120 mm thick pillars, they are using metal strips, which they first screwed onto the window, then after putting the window into the building, screwed onto the pillars. 

Just as I could have predicted that the windows would have arrived an hour and a half late, I should also have been able to predict that they would try to get these difficult windows in as quickly as they could, while the crane was still there, with decisions made on the site, and an attitude of "it'll be right". Although I shouldn't have been surprised, I was shocked to see that the three south-facing upstairs windows had all been installed when I got back from teaching my afternoon lessons a couple of hours later.

When I first saw these metal strips sticking out beside the windows, they started ringing alarm bells as thermal bridges. Especially these ones, on the opening window upstairs on the South East. Obviously the assembled window is heavy, and they wanted to get it in when the crane was there, but each glazed wing could be removed, and the three parts could be lifted and put into place. In this case the metal strips are unnecessary. I spoke to the window importer who did not seem terribly interested in thermal bridges. I also contacted someone at Passive House Institue in Germany who seemed much more interested, although has not got back to me yet. I've since calculated them at 0.0009 W/K per strip. 

The manager of Pazen in Germany was also interested but seemed confident the thermal bridge effects were negligible. He was more concerned that the window in this picture was moving, and so did not need to be fixed with steel strips. He had sent the right number of steel strips for the two fixed windows, so he was worried that we hadn't used enough on the big heavy fixed windows to keep them in the house.

In the case of the large window in the middle, the metal strips have been screwed onto the frame after the compriband was added. This means that the compriband has not been able to expand to fill the gap between frame and wall, doing its job of insulator and airtightener. You can see a bit of daylight. If we can see daylight, the air will be able to see daylight too, and the airtightness will drop. I need to find out what they are going to do about this. The carpenter and site foreman seem to think the job is done. The architect thinks that they have been temporarily put into place and will all be reinstalled. The insulation and airtighntess contractors are on site at the moment, and I think airtightness issues are in their ballpark. Perhaps they will be going around with a needle later checking the corners.

The smaller window to the west (on the right looking out of the house) seems to be fitted correctly, at least if we can really ignore the steel strip thermal bridge effect, and if two strips on each side is going to hold it in place.

So that's one out of three. 

The house feels really good with windows, and it may make it a bit cooler over the summer, but with the vapour barrier almost completed, they will have to keep the windows open to avoid suffocation.