In this master’s thesis I explore the effects of green roof systems on a building’s energy efficiency and thermal response. I wanted to determine the effect of installing a green roof on a multi-storey apartment building in Ljubljana as part of an energy efficiency renovation, to determine the effect of different variations of green roof and thermal insulation on the building’s energy needs. To that end I created a model of the building using the Design Builder software, complete with characteristics and schedules of the systems, materials, furniture, users and the building’s location. I wanted the model to be able to produce an accurate estimation of the building’s energy needs. Within that model I then defined sixteen different combinations of the building’s envelope; I combined a bare envelope, without green roof systems or thermal insulation with three different green roofs and thermal insulation in three different thicknesses. I ran an analysis of energy needs for the otherwise identical building models with different envelopes, determining the energy needs for heating and cooling for each individual envelope variation for the whole year, and separately for hot and cold parts of the year, for the entire building as well as for individual storeys. The thesis includes the definitions of the building and greenery systems, analyses of energy needs for each envelope variant, a discussion on the effects of different green roof variants, thermal insulation and the combination of both on a building’s energy needs. The results have shown, that the use of a green roof as an energy-reducing measure is most effective in the non-insulated variants of the building envelope. The effectiveness of the green roof as a measure to reduce energy needs decreases with increasing thickness of conventional thermal insulation. The most effective variant reduced energy needs for heating and cooling by as much as 52,16 %, with the effects of the greenery itself ranging from 20 % for buildings without thermal insulation to about 1,5 % for buildings with green roofs and thermal insulation.
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