Outside the wall

Dan and Sarala’s blog from Hohhot

Our windows got replaced

24 Oct 2014

The notice went up in August: our apartment complex would be undergoing renovation to improve thermal efficiency. Work crews would be replacing everyone’s windows and adding insulation to the walls and roofs. Apparently all we had to do was stay home to unlock the door.

We knew our turn was coming up soon when these stacks of new glass panes showed up in front of our building:

The window changeover took about a day. First a crew came to remove the old windows, which involved scoring the glass panes, carefully breaking out the pieces, and carrying them down six flights of stairs in a cardboard box. Then they sawed the metal frames into pieces with a grinder and yanked them out of the wall with a crowbar (below left):

The right-hand picture above shows the new window frame being installed. There’s no glass in it at this point, they are just stapling the empty frame in place. In fact, several hours passed between them removing the old glass and installing the new glass. During this period it got incredibly windy in the apartment:

An architect acquaintance back in Seattle explained to Dan (while they were looking at Hohhot on Google Earth) that these buildings are probably designed to promote cross-breezes: they’re long rectangles with the long sides facing roughly north and south, and each unit has windows on both sides. The sun heats up the south wall, creating a temperature gradient, so as soon as you open the windows there’s a breeze, regardless of whether it’s actually windy outside.

Well, compared with opening the windows in the normal way, having all the glass removed multiplies the open surface area by about six. The wind speed reflected this on some level.

They finished the install by midafternoon. The new windows are better insulated both thermally and acoustically, and also clearer to look through. Here are before and after shots (reusing a photo from an earlier post). You can see that the old version had two separate sets of single-paned windows, instead of one set of double-paned:

Though it only took one day to do our apartment and the 17 others in our column, the window-changing process for the entire complex has taken about two months. Here’s a small fraction of the ocean of broken glass littering our neighborhood, which is getting carted away trikeload by trikeload:

At the same time, a different construction crew has been adding a layer of styrofoam insulation to the outside walls. This process has also been very interesting to watch, so we’ll probably post about that soon.

By the way, we’ve never personally experienced a window replacement in the US, so we’ll leave any comparisons up to you.