Outdoor testing, analysis and modelling of building components

In 1993 [1], a set of papers was presented on the theme of thermal experiments in outdoor test cells. In the intervening 13 years, there have been several advances in the test procedures, the analysis of the measured data to extract standard performance characteristics, and the link with modelling and simulation. The papers included in this special issue focus on developments made in a series of research projects funded by the Commission of the European Community, all of which have included a significant element of outdoor testing of building components. The arguments for using outdoor test cells are still relevant. High quality laboratory facilities exist for testing components (e.g. hot-box facilities for measuring thermal transmittance, spectrophotometric testing for optical properties of glazings, solar simulators and climatic chambers for testing the output from photovoltaic modules) that are accurate and repeatable. However, they tend to be steady-state tests and do not take into account the dynamically varying boundary conditions that the components are subjected to when used in the building envelope. The obvious solution is to test the components when mounted on a building in typical operational mode. However, in practice this has been shown to be highly complex - even in unoccupied buildings, it is difficult to measure all the required inputs (e.g. constructional details, air movement, heating and cooling system operation, and external climate) to the level required to get reliable estimates of component performance. Although some attempts have been made to measure in dedicated full-scale buildings (e.g. [2], [3] Swinton MC, Moussa H Marchand RG. Commissioning twin houses for assessing the performance of energy conserving technologies. Performance of exterior envelopes of whole buildings VIII integration of building envelopes, (NRCC-44995), Clearwater, FL, December 2001. p. 1-10.[3] and [4]), the results can still have significant uncertainties and/or the facilities are very expensive to construct and monitor.