Sensitivity analysis and validation of buildings' thermal models using adjoint-code method

The objective of this study is to present a validation method for simulatio n codes describing thermal behavior of buildings. Beginning with the classi cal form of comparison of theoretical and experimental results, it is propo sed to improve the procedure by calculating the degree of uncertainty assoc iated with the theoretical results. It can be shown that uncertainties asso ciated with code input data, that is, the simulation parameters, propagate through the calculation and generate a range of uncertainty in the results. After describing the problem and objectives of the study, the computation code analysis will be presented. This concerns use of the CA-SIS (Condition nement d'Air-Simulation de Systemes) code, and employs the TRNSYS calculati on environment. Experimental validation studies for the evaluation of this code have been carried out using ETNA (Essais Thermiques Naturels ou Artifi ciels) cells, which have been constructed and are maintained at a site near Paris. These cells and experimental procedures are described. To determine ranges of uncertainty in the numerical results, a sensitivity analysis is first carried out by an "adjoint" method. This method and the relationship linking the uncertainty to calculated sensitivities is presented. Notably, it can be demonstrated that the adjoint method simplifies the calculation o f uncertainties. The results presented focus on the cell air temperature. T he experimental air temperature evolves during the climatic heating sequenc e within the range of uncertainty of the theoretical results. It can be ded uced that the first step of validation being reached, the developer of CA-S IS code can discuss the complete validation for this configuration. The hig h sensitivity of the internal air temperature to the parameter of heating p ower shows the limitation of isothermal air volume hypothesis. From this it can be concluded that it is necessary to improve the numerical modeling of the injection heating power. (C) 2000 Elsevier Science S.A. All rights res erved.