Energy saving and thermal comfort interventions based on occupants’ needs: A students’ residence building case

Abstract

The existing residential building of the Technical University of Crete students has studied as well as the current indoor conditions and the occupants’ energy consumption behaviour and satisfaction, in order to identify the proper building interventions. The current energy performance of the building is poor like the majority of the old social buildings in Europe; in the social buildings in Greece, passive solar and cooling principles were not the main priority for the past architects and engineers.The survey highlighted problems such as insufficient lighting (20% use artificial lighting at noon in winter and 24% in the afternoon in summer) and thermal discomfort, especially in winter (only 17,65% were satisfied compared to 37,25% in summer). High values of humidity and insufficient ventilation were also observed.Five scenarios concerning the reduction of energy consumption were chosen towards a nearly zero energy building with a reasonable payback period. The annual dorm building energy consumption is about 70,1 kWh/m2. The first investigated scenario of thermal insulation on building envelope presents 10% savings leading to a reduced consumption of 63,1 kWh/m2, while correspondingly the green roof achieved an 1,7% reduction (68,9 kWh/m2), LED bulbs 14,6% reduction (59,9 kWh/m2) and substitution of windows 17,4% reduction on energy consumption (57,9 kWh/m2). The combination scenario includes all the above described interventions summing total savings up to 36% (44,9 kWh/m2).Given the newly reduced consumption, the installation of a self-producing PV plant was studied according to three alternative scenarios; achieving 50% of total electricity needs, 100% of total needs and optimal use of freely available roof space. The installation of a PV plant suitable for the available roof space achieved 62% savings compared to initial energy consumption, a very satisfactory result for the target of near-zero energy performance in the dormitory building.