Your HVAC System Is the Faucet; The Building Envelope Is the Cup
Last Saturday, I was doing some stuff around the house, and my wife had the radio tuned into one of those home repair talk shows. I don't listen to those shows much because they usually say something that drives me crazy. They do seem to be getting better, though, and what I heard last Saturday indicates that a little bit of building science and house-as-a-system thinking may be making its way out into the trenches.
Anyway, the host of the show was talking to his guest (an HVAC contractor, I believe) and threw out a metaphor that I'd never heard before. Here's my paraphrased version of what he said:
"Your heating and cooilng system is the faucet. Insulation is the cup. If your insulation isn't adequate, a lot of that heating and cooling you're providing will leak out."
I thought it was brilliant! The only problem is that he caught only the insulation part of the building envelope and didn't mention the air barrier, which is a hugely important part of the cup. Still, it's a great metaphor with the substitution of 'building envelope' for 'insulation.'
Building Science 101
More Insulation or High Efficiency Heating & Cooling System?
An Incomplete Building Envelope Doesn't Work
Photo by SMercury98 from flickr.com, used under a Creative Commons license.