Saturday, November 1, 2008

What you can not measure you can not control

Or, what you did not measure you cannot evaluate, the latest being my own adaptation of the quote. So, as I mentioned in the last post, I am in the process of insulating the attic. Yes, it is still not finished. It is a lot of work and dirty work as well, as it involves crawling in the floor to unaccessible corners to staple the stuff.
I am using a material called Xlmat which is a reflective barrier together with standard wool insulation. it is 3cm thick and composed of 17 layers of materials - reflective layers, plastics and wool. Although as far as I understood you cannot really give a R value to a reflective barrier, I think I read somewhere that this material is equivalent to a material with R=6 (SI).
Meanwhile I have been doing some logging of the temperatures inside and outside the attic - see previous post - so that, as the title indicates, I can control and evaluate the effectiveness of the insulation.
After having the logging on and off for some time, it happened that things were not always working fine, with the contacts and strange values were being read. So I decided to add a display to see what was going on. So I bough a one line, 16 characters LCD and plugged it to the Arduino. Here is my current setup.

AH! almost forgot: plugged the wires for the in and outside lm35 wrong, so in is out and out is in :)

It appears that the display has some particularities, which I will elaborate upon in the next posts. I'll post a graphic with the results soon...but I think there are so many factors in play that I might not be able to conclude anything...While I was preparing this post, I came across this other quote:

"measure what is measurable, make measurable what is not: - Galileo