A New Experiment and Modelling Work to Jointly Identify the Building Envelope’s Thermal Parameters and a Physical Solar Aperture

Abstract

Co-heating tests have been used by many researchers for the characterisation of the heat loss coefficient (HLC) of building envelopes. Measurements may be analysed through static, transient or dynamic approaches. A reliable identification of the HLC is obtained by the joint identification of multiple parameters including the solar aperture. The solar gains continuously depend on the relative position of the sun with regard to the building’s glazed components and on the type of emitted radiation, ranging from diffuse (overcast sky) to beam (clear sky). However in state-of-the-art static co-heating tests, only the daily mean solar radiation is analysed, leading to the identification of a static solar aperture (A_w). Practitioners then have to rely on several weeks of continuous measurements under representative but not extreme weather conditions to derive regression lines with acceptable correlation coefficients between the daily means of the measured variables. Finally, the obtained results do not allow performing dynamic predictions since the model is static. This paper first explains the advantages of the newly developed experimental protocol itself, compared to other dynamic tests recently applied in situ. It also presents a new methodology to better take the solar gains into account during the dynamic analysis of a short experiment. The proposed methodology jointly enables a more accurate identification of the general heat loss characteristics of the building and of a physically-interpretable and climate-independent solar aperture. It can be seen as the equivalent total solar transmission coefficient of the envelope under normal incidence, multiplied by the total glazed surface of the whole building envelope, and is denoted as gA _eq,tot,⊥ (replaces A_w). The proposed method can be applied to characterize the static energy performance of the building and also to predict (or even control) the energy consumption under specific weather forecasts or normalized conditions.

Lethé, G. (2015) A new experiment and modelling work to jointly identify the building envelope’s thermal parameters and a physical solar aperture In; Gorse, C and Dastbaz, M (Eds.) International SEEDS Conference ,17–18 September 2015, Leeds Beckett University UK, Sustainable Ecological Engineering Design for Society.