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The Phase-change Revolution Optimizing metal roofing and wall systems with advancing technology by David A. Brown, PE Photo © Fabral THE CUSTODIAN AT ASHEBORO CHURCH OF GOD (NORTH CAROLINA) HAD A WELL-WORN ROUTINE DURING SUMMER MONTHS. EVERY SATURDAY, HE WOULD TURN ON THE CHURCH’S AIR- CONDITIONING (AC) AT 3 P.M. TO ENSURE THE SPACE WAS COOL AND COMFORTABLE FOR MORNING SERVICE THE NEXT DAY. THE 1115-M 2 (12,000-SF) BUILDING NEEDED AN 18-HOUR COOL-DOWN TIME. In a time where sensitivity to environmental impacts is growing and utility bills are rising, this is unacceptable. Buildings demand reliable, high- thermal performance envelope solutions that: • drive energy-efficiency; • prevent heat loss; • eliminate thermal bridging; and • control solar gain over its operating lifetime. These performance criteria are key factors in minimizing energy running costs and reducing carbon emissions, while maximizing property value and lease-out opportunity. When evaluating a solution for the Asheboro church’s re-roofing application, the construction team was faced with these performance objectives. In June 2011, after investigating new innovations in sustainable technology, the team opted for phase-change materials (PCMs). A ‘roof hugger’ technique—a sub-purlin system that fits on existing metal panels, supports new panels, and can be configured to add insulation— was used for metal-over-metal re-roofing. The new panels were seamlessly integrated with sheets of a plant-based compound that absorbs heat 60 the construction specifier | april 2013 CS_April2013.indd 60 3/14/13 11:49:37 AM