A Mobile Facility for Measuring Net Energy Performance of Windows and Skylights

A Mobile Window Thermal Test (MoWiTT) Facility is being built at Lawrence Berkeley Laboratory in order to use direct measurement to verify predictions of the net energy performance of fenestration systems and other complex elements of the building envelope. It consists of one or more wheeled modules together with an instrumentation van. Each module contains two room-sized (2.4m x 3.lm x 2.4m) guarded calorimeters, each capable of accurately measuring the net energy flow through a sample under all conditions of solar gain. Expected performance of the facility is calculated using the program BLAST. We conclude that it provides a much more accurate measuring capability than the passive cell commonly in use.