Recently, U.S. Lawrence Berkeley National Laboratory and Brazil’s Federal University of Santa Catarina released the result of their joint research and announced that the researchers have developed a portable window energy measuring device which can assess the energy performance of windows without removing them from the building site. The new energy meter is the approximate size of a shoe box and can be easily attached to the surface of the window glazing. The instrument automatically calculates and assesses the overall energy efficiency performance of a window by measuring the thermal and optical properties of windows in the field. It’s easy to carry and install, producing highly accurate readings. The Energy Department estimates that the amount of energy lost annually through windows in the United States corresponds to approximately $40 billion. When incorporated with international energy standards, the new instrument will facilitate building energy efficiency rating, energy auditing along with other standardized assessment procedures.