This presentation describes the results of a parametric analysis that was performed to assess the effects of increasing roof insulation and changes in roof membrane absorptivity and emissivity on the accumulation of snow on roofs. Melting of snow is sensitive to changes in temperature and the amount of solar radiation. Structural failures due to excess snow load frequently occur due to the accumulation of snow from multiple events rather than a single snow event. Reduced heat loss due to building energy efficiency improvements mandated by energy codes reduces the duration when snowmelt may occur and snow from subsequent storm events is more likely to accumulate before it completely melts.
Improving the energy efficiency of buildings has been a significant goal for many decades and has provided significant cost savings to building owners and reduces our reliance on non-renewable energy. Low-slope roofs have traditionally consisted of ballasted systems, built-up membranes, and other dark-colored membranes, sometimes with little underlying insulation. For new construction, energy code changes have increased the required thermal resistance of roof insulation and more frequently, roofs are light-colored, even in northern climates. Similarly, existing buildings subject to roof membrane replacement are often required to add insulation prior to installing the new roof membrane. The effect of building code changes for roof insulation requirements on design snow loads are discussed.