Toward Accurate Prediction of Comparative Fenestration Performance

The importance of going beyond laboratory measurements to prediction of field performance of fenestration systems is noted. The current state of the art in energy prediction related to fenestrations is discussed; a critique of the ASHRAE U-value is presented, and current questions about film coefficients are put into context. Ambiguities in the modeling of complex glazing systems are pointed out. Several questions about the convective processes in simple enclosures are raised, and the importance and uncertainty of solar gain calculations is underlined. It is concluded that accurate field measurements are needed to inform the predictive enterprise. A facility to make these measurements is described and current progress on calibrating this facility is presented.