An approach in architectural design of energy-efficient timber buildings with a focus on the optimal glazing size in the south-oriented façade

The current research presents an architectural design approach to determine an optimal proportion of the glazing areas in regard to energy-efficiency of prefabricated timber-frame buildings, with a special focus on the south-oriented glazing surfaces. A parametric analysis is performed on the variation of the glazing-to-wall area ratio (AGAW) from 0% to 80% for six different exterior wall elements with different thermal properties. Modifications are performed for the main cardinal directions, while a detailed analysis is carried out only for the south façade. The impact of the presented variable parameters on the energy demand for heating and cooling is analysed with the use of the PHPP software. A basic theoretical contribution of the present research is transformation of a complex energy related problem to only one single independent variable – that of thermal transmittance of the wall elements (Uwall-value), with a view to determining the optimal glazing area size (AGAWopt) for all contemporary prefabricated timber construction systems. The main aim of the current study is to offer architects a simple and useful shortcut to energy-efficient design of prefabricated timber-frame buildings. The use of mathematical linear interpolation is therefore presented as a simple method for predicting an approximate energy demand with respect to AGAW and Uwall-values.

► The presented approach enables a fast and simple pre-estimation of the energy load. ► The determination of a relation between the optimal glazing ratio and Uwall-value. ► The generalisation of parameters on Uwall-value as the only variable parameter. ► The presented generalisation is applicable to timber construction in general. ► Findings important for the renovation principles of the old timber-frame housing.