An actuarial method has been developed for determining energy savings from retrofits from energy use data for a number of buildings. This method should be contrasted with the traditional method of using pre- and post-retrofit data on the same building. The actuarial approach derives, from a database, probability density functions (PDFs) for energy savings from retrofits by creating peer groups for the user's pre/post buildings. From the energy use distribution of the two groups, the savings PDF is derived. This provides the basis for engineering analysis as well as financial risk analysis, leading to investment decisions. Several technical issues are addressed: the savings PDF is obtained from the pre- and post-PDF through a convolution. Smoothing using kernel density estimation is applied to make the PDF more realistic. The number of buildings in a peer group can be increased through a neighborhood methodology. Correlations between pre- and post-buildings are addressed to improve the savings PDF. Sample size effects are addressed through the Kolmogorov-Smirnov tests and quantile-quantile plots.