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Maverick NYC mechanical systems designer Henry Gifford has long been a critic of LEED, arguing that it encourages the wrong things, and doesn't go far enough to ensure that certified buildings really save energy or provide good air quality. I have great respect for Gifford and the work he does to design and commission low-energy buildings with great ventilation on very tight budgets. Unlike too many practicing engineers, he knows exactly how much energy his buildings are using.

In this final installment about insulation we'll take a look at the family of rigid boardstock materials. Unlike fiberous or spray-foam insulation that is installed in wall or ceiling cavities between the studs, rafters, or joists, boardstock insulation is applied either on the interior or exterior surface, spanning across the framing.

"Water shortages are expected to become more and more common in the coming decades. A 2003 report by the U.S. General Accounting Office reported that 36 states are likely to experience water shortages by 2013."

"Water use in and around buildings, from both public water supplies and well water, accounts for about 47 billion gallons (180 billion l) per day, or 12% of U.S. water use...

In recent columns, we've looked at cellulose insulation as well as fiberglass and other batt insulation The other option for filling wall and ceiling cavities is foam insulation that is sprayed into the cavity. There are several such materials that are used for this application, all installed by professional insulation contractors.