EMPIRICAL VALIDATION OF BUILDING ENERGY SIMULATION PROGRAMS

The largest-ever exercise to validate dynamic thermal simulation progr ams (DSPs) of buildings has recently been completed, It involved 25 pr ogram/user combinations from Europe, the USA and Australia, and includ ed both commercial and public domain programs, Predictions were produc ed for three single zone test rooms in the UK. These had either a sing le-glazed or double-glazed south-facing window, or no window at all. I n one 10-day period the rooms were intermittently heated and in anothe r 10-day period they were unheated. The predictions of heating energy demands and air temperatures were compared. The observed interprogram variability was highly likely to be due to inherent differences betwee n the DSPs, rather than the way they were used. Predictions of the dif ference in performance of two rooms were no more consistent than predi ctions of the absolute performance of a single room, By comparing the predictions with the measurements and taking due account of experiment al uncertainty, the DSPs that are likely to contain significant intern al errors are distinguished from those which, in these tests, performe d much better. The likely sources of internal error are discussed. It is recommended that empirical validation exercises should consist of a n initial blind phase in which program users are unaware of the actual measured performance of the building, and then an open phase in which the measurements are made available. The work has produced five empir ical validation benchmarks, which have significant practical benefits for program users, vendors and potential purchasers. There is consider able scope for improving the predictive ability of DSPs and so suggest ions for further work are made. (C) 1997 Building Research Establishme nt. Published by Elsevier Science S.A.