Building Energy Efficiency Program is an integral part of energy efficiency section of the Center for Energy Efficiency and Renewable Energy. CEERE's close relationship with the University of Massachusetts and the experience and university roots of the CEERE staff provide it with a unique opportunity to administer successful research programs in building energy efficiency. CEERE staff has extensive experience in areas of thermal performance of building envelopes and fenestration systems, simulation of energy use in buildings, energy audits, building commissioning and retro-commissioning, among other things. The following areas are subject of current research: