Post-occupancy evaluation of a recent energy efficient office building : FA 1 Environmentally friendly concrete : SP Insulating and energy preserving concrete

This report is a post-occupancy evaluation of a recent energy efficient building. The building is located in Professor Brochs gate 2, in the city of Trondheim, the third largest Norwegian municipality. The building was erected in 2008-2009 and got partially moved in during September 2009. The building owner, KLP Eiendom, wanted to build an energy efficient office building. A target of 86 kWh/m²·yr for delivered energy (all electrical appliances included) was defined during the design stage. Among all energy efficient measures that have been taken, one consists of using fair-faced concrete ceilings instead of suspended ceilings to take advantage of the concrete’s thermal inertia. The objective of the postoccupancy evaluation is to verify the energy target, to quantify the users’ satisfaction rating and to get feedback on the use of fair-faced concrete ceilings. Real conditions for operation differ often from the ones defined during the design stage. In our case, the main difference concerns the occupancy level of the whole building. The office building was put to use in September 2009 but wasn’t rent in its entirety at that time. Some areas get rent in the course of 2010, others are not moved in yet. The real demand for delivered energy is then difficult to compare with the target, but is definitely lower than in newly built office buildings without focus on energy efficiency. There is no use of local cooling in the office areas of the building. The temperature isn’t experienced too hot during summer, showing than carefully designed internal gains and controlled solar gains can be eliminated by ventilation cooling. The users’ survey shows that a majority of the respondents experience too low indoor air temperature during summer. The users judge favourably the design of the ceiling, with fair-faced concrete slab and hanging acoustic insulation panels. After only 16 months of occupancy and a regular moving in of new tenants, the technical installations are not optimal operated yet, especially those producing cooling and distributing heating.