Passive Solar Stages a Comeback
Others say that solar is dead, but Harris Hyman is convinced it's on the rebound. Energy-efficient window glazings are mak- ing the difference, he says.
The Case of the Disappearing R-Value
Manufacturers have long claimed that the higher R-value of urethane and polyisocyanurate more than compensates for their higher cost. But research now indicates that even the so-called "aged" R-value of these products is lower than previously believ