Massachusetts is leading the way to more efficient buildings with the inclusion of continuous air barrier systems in its new Commercial Energy Code, a trend that is expected to spread throughout the Northeastern United States in the near future.The state is the first jurisdiction to mandate air barrier systems in non-residential construction. The new Commercial Energy Code conforms to the U.S. Department of Energy’s (DOE’s) program goals to reduce building energy consumption by 25 percent by the year 2010, and 50 percent by 2020. Air barrier systems will play an important role in meeting the DOE goals. The code is the culmination of nearly three years of work.Air barrier requirements appear in section 1304.3 Air Leakage of 780 CMR, Chapter 13. “1304.3.1 Air Barriers: The building envelope shall be designed and constructed with a continuous air barrier to control air leakage into, or out of, the conditioned space.” The code stipulates the following characteristics for the air barrier:Continuous, with all joints made air-tight.Air permeability of less than 0.004 cfm/ft2 under a pressure differential of 0.3 in. water (1.57 psf).Capable of withstanding positive and negative combined design wind, fan, and stack pressures on the envelope without damage or displacement.Will not transfer wind load to the structure.Durable and maintainable.Joined in air-tight and flexible manner to the air barrier material of adjacent systems, allowing for relative movement of systems.Connection to be made between: foundations and walls; walls and windows or doors; different wall systems; wall and roof; wall and roof over unconditioned space; walls, floor, and roof across construction, control, and expansion joints; and walls, floors, and roof to utility, pipe, and duct penetrations.One of the materials that meets – and in some cases exceeds – these requirements is Spray Polyurethane Foam (SPF). Many people are familiar with SPF roofing systems, but they don’t know that SPF is a two-component product that is manufactured on-site but engineered on the molecular level to optimize performance for a specific application.SPF has a closed cell rigid formulation that creates an effective air barrier, as well as providing the highest level of thermal insulation. Usually, additional vapor barrier protection is not necessary.SPF air barriers offer peak wind load resistance; seamless, monolithic construction; and almost zero air permeability. SPF conforms to unusual shapes and is rigid, self-supporting, and fully self-adhering. Installation is performed in a single operation for lower labor costs and does not require fasteners, gluing, or torches.Buildings professionals have successfully used SPF air barriers for more than 10 years on all types of industrial, commercial, and industrial buildings, both low- and high-rise. Typical applications include cavity walls, pre-cast concrete walls, curtainwall, and IPS walls.Currently the product manager for BASF’s Spray Foam Group (www.basf.com/spray), Wyandotte, MI, Tom Harris has worked for 20 years in the polyurethane systems business. He represents BASF as a founding member of the Air Barrier Association of America.