Thermal simulation of an attached sunspace and its experimental validation

Usual thermal-simulation models are not well suited for highly-glazed spaces, mainly due to the fact that they do not properly consider solar radiation distribution and reflection inside the sunspace. This paper deals with a new thermal-simulation model for an attached sunspace. The main characteristics of the mathematical model are explained. For the present model, special care is taken for the modelling of the internal long-wave radiation exchanges and solar radiation distribution within the sunspace. The validation of the model is made by comparing the calculated results and experimental data, obtained from a full-scale test facility, which is also described. Good agreement is obtained between numerical results and the experimental data. The mean difference between the peak calculated and measured air temperature at the center of the sunspace is equal to 2.4 degrees C. The differences between results of the model and measurements are about 11%, in terms of net energy supplied to the adjacent room by the sunspace. Moreover, a sensitivity analysis is made in order to determine which parameters of the model have the strongest influence on results. It is also explained why approximations normally used in common thermal simulation models, like distributing the transmitted beam solar radiation onto the interior surfaces by the view factor method, is not well suited for highly glazed spaces. This model is an appropriate tool for determining the energy savings attained through the construction of a sunspace attached to a dwelling. This model is therefore considered useful in helping architects to design solar passive housing. (c) 2006 Elsevier Ltd. All rights reserved.