With New York City’s 80×50 initiative to reduce greenhouse gas (GHG) emissions 80 percent by 2050, the stakes are high for the city to adopt progressively more stringent energy codes. Similarly, the Sustainable DC Plan professes the lofty goal of making the nation’s capital “the greenest, healthiest, and most livable city in the nation.”
Insulation manufacturers have devised numerous ways to improve the thermal performance of their products. Adding carbon or alumina particles to expanded polystyrene (EPS) increases infrared reflectance, and hence boosts R-value. For buildings that need heat stopped during the day and released at night, there are phase-change materials.
Many designers and specifiers understand controlling air, vapor, and thermal transfer helps mitigate moisture problems within the building envelope. Moisture accumulation is a performance adversary that can lead to structural deterioration, finish damage, organic growth, and reduced building longevity.
Masonry materials and wall systems, with their inherent thermal mass characteristics, provide designers with many options to achieve energy-efficient designs. This article illustrates examples of wall configurations that exceed national building code requirements and high-performance standards, taking into account factors like increased R-values for non-mass opaque walls (prescriptive design), continuous insulation, requirements for R-value reductions caused by thermal bridging, mandatory continuous air barriers, and options for building energy design.
Both conductive heat transfer and air leakage through the building enclosure have been identified as obstacles to truly energy efficient buildings. This article delves into the necessity for proper detailing of both continuous insulation and fluid-applied air barriers, pointing out the difficulties in avoiding pitfalls such as thermal bridging in wall assemblies. It also explores why more insulation is not necessarily a means to increase energy efficiency.