Parametric study of a cost-optimal, energy efficient office building in Serbia

Recent building regulations in Serbia prescribe the design of highly insulated, airtight buildings with low U-value glazing. Serbia has continental climate with hot summers, so that for office buildings, whose internal gains are higher from the presence of people, computer systems and lighting, this means that far more focus has to be put on cooling demands than on heating demands. This shift toward cooling is studied here through exhaustive simulation of combinations of selected passive solar design parameters for a model of an office building in Belgrade. Design parameters include glazing type, window-to-wall ratio of façades, presence of exterior shading and U-value of opaque envelope components. Optimal variants of the model have been determined with respect to construction cost and heating, cooling and lighting energy use. Results reveal that exterior shading, which has to sustain occasional strong winds in Belgrade, is too expensive to appear in cost-optimal solutions. Hot summers of Belgrade climate imply that cost-optimal solutions have close-to-minimal window-to-wall ratio at the southern façade and significantly larger window-to-wall ratio at the northern façade. Results further show that glazing in cost-optimal solutions has to have small U-value and medium solar heat gain coefficient, although specific choices of optimal glazing type, as well as thermal insulation level, depend on future electricity prices. The case study is repeated for climates of Frankfurt and Stockholm as well, which yield similar results with respect to glazing type and the absence of exterior shading, but with different patterns of window-to-wall ratios at the southern and northern façades.