The document summarizes research on highly insulating windows conducted by the Windows and Daylighting Research Group at Lawrence Berkeley National Laboratory. The group consists of 10-15 researchers dedicated to improving window performance. Key areas of focus include developing triple glazings, improving frame performance, and testing low-e storm windows as a cost-effective way to increase insulation. Preliminary estimates show low-e storm windows can reduce whole home heating energy use by 19-27% over a winter season with a payback period of 3-5 years depending on the home.