OptiMiser recently integrated the latest database of 30-year weather normals from NOAA's National Climactic Data Center. This data set covers the three decades from 1980 to 2010, replacing the weather from the oldest decade of the 1970s with the decade of the 2000s. This is important because the 2000s reflected recent warming trends and averaged 1.5 degrees warmer than the 1970s. This increased the overall averages for the 30-year period by about 0.5 degrees. It is important for auditors to be aware that if the warming trend continues, estimates based on the 30-year averages are still likely to under-predict future cooling loads and over-predict future heating loads on average. However, the increased variability brought on by climate change will likely mean that year-by-year and region-by-region, the differences between actual yearly loads and those predicted by the 30-year normals will become increasingly variable.
