Optimal design of timber-glass upgrade modules for vertical building extension from the viewpoints of energy efficiency and visual comfort

Abstract

In search of new approaches to building renovation, attempts have been made to design energy-efficient upgrade modules for the purpose of vertical extension of buildings. The design of such modules often fails to meet the requirements for visual comfort, which is important for the health and well-being of the occupants. Therefore, the aim of this study is to define an optimal upgrade module design by regarding not only energy efficiency but also visual comfort aspects. The goal of this study is the development of an optimization model, including the energy efficiency and daylight performances, within which optimal glazing shares of south oriented facades of timber-glass upgrade modules can be calculated, taking into account realistic architectural design and the discrete dimension of windows. Also, the possibility of defining optimal glazing shares of southerly oriented façades when placing the windows facing other cardinal directions is explored. Accordingly, a multi-parametric mixed-integer non-linear programming optimization, which included the development of an optimization model in which the total energy need represented the objective function that was subjected to the constraints of daylight performance to define an optimal glazing size, was performed. The results show that optimum design for timber-glass upgrade modules is a combination of glazing shares of between 25.0 and 30.0% for north- and east–west facing facades and between 20.0 and 30.0% for south-facing facades that offer daylight factors of between 2.0 and 3.0%. These findings apply to modules of comparable characteristics, in terms of size, climate conditions and thermal transmittance of building envelope.