NEW YORK, NY — Thermal bridging is a characteristic of some materials, such as steel studs, to transmit temperature differences through a wall assembly, short-circuiting the insulation that abuts it. The Consortium for Advanced Residential Buildings (CARB) uncovered such a thermal bridging problem in the design of Melrose Commons, a development of attached, three-family townhouses in the Bronx, New York.

The 90-unit project was established and is funded by the New York City Department of Housing Preservation and Development under its New Homes Program, and developed by the New York City Housing Partnership and the Seavey Organization.

A proprietary panelized concrete exterior wall system is being used instead of the block-and-plank townhouse construction used by Seavey in the past. The advantage of the new system is speed of construction, labor savings, and tightness of the envelope. CARB analyzed the exterior wall assembly for energy efficiency and discovered that the steel studs were permitting excessive heat loss through the wall. A more efficient assembly was developed to address the problem.

Originally, there was a 2-in. airspace behind the brick veneer, and R-11 batt insulation between the studs. This was changed to a 1-in. airspace and 1 in. of rigid insulation to significantly reduce the thermal bridging.

For the Melrose project, the New York State Energy Research and Development Authority (NYSERDA) contributed $1,500 toward each three-family home as part of the Energy Star™ Homes program.

Publication date: 01/21/2002