New York first passivhaus ...

Replies to This Discussion

Permalink Reply by John Snell on August 21, 2011 at 5:52pm

You should be skeptical, Davide!! Something is clearly not right. Windows are about 20% reflective but all of them at that angle could be reflecting the same cold sky.

 

I think the interior temperatures of the buildings were different. I have R=10 windows and even they are warmer than my R=45 walls!

As the image below shows, we can make windows appear pretty much an... Interior temps in this image were all the same; the difference is what is being reflected, cold sky (top), warm surroundings (bottom) or a mixed background (middle).

Permalink Reply by John Snell on August 21, 2011 at 5:55pm

Here is another image showing R=10 windows (Serious brand) on the right and conventional double-glazed, nitrogen-filled windows on the left (there is a screen on the right window of these). Interior temperatures are identical in both rooms.

Permalink Reply by Ed Minch on August 25, 2011 at 10:44am

John

Is the emissivity difference between the glass and the wall making a difference too?

Ed Minch

Permalink Reply by John Snell on August 25, 2011 at 12:28pm

It is certainly possible as I no longer have the exact specs for the older windows. My belief, however, is that exterior surfaces of both old and new glazings are uncoated so what we are seeing is related only to the difference in actual heat transfer.

For the other image (3 windows stacked), all three windows are identical. The difference in "apparent temperature" is entirely due to differences in the reflected background temperatures.