Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
As a result of high energy use in buildings, the rules for energy conservation has, since 2006, become stricter in Sweden. Today, it must be verified that buildings meet the requirements of specific energy consumption (energy consumption per square meter heated floor area), with a calculation of the energy performance in a simulation program and by measuring the energy performance when the building is done. This in addition to the requirement that the average coefficient of thermal transmittance and the installed electrical power, for electrically heated buildings, must be calculated at the design stage. It is, however, often noted that the result of the calculations and measurements differ from each other, and that the measured values often are higher than those calculated. In collaboration with NCC and Mälardalens University, an investigation was made in which the calculated and measured values of energy were examined for a number of apartment buildings, schools and sports halls, to identify causes of difference, and to identify priority areas of work within, above all , energy simulation and energy follow-ups. It turned out that the difference is largely influenced by the type of the building, as it differed between apartment buildings, schools and sports halls. In addition, the amount of window area turned out to have impact on the results, as it allows for more airing, which is a factor that is very difficult to anticipate for the simulations. The windows ability to let in sunlight is another factor that is hard to anticipate. Furthermore, it was discovered that the standard values for the assumed energy consumption for domestic hot water is often too high. In some cases the assumed heated floor area and the assumed outdoor climate data differed between calculations and measurements. It also happens that heat losses from culvert pipes to the ground is not taken into account when calculations are done. As for priority areas of work, judging by the results of this work, better behavior related input data and standard values for, above all, energy consumption for hot water needs to be developed. There has to be more diligence when ensuring that there are same conditions for calculations and measurements, and this could mean that those who perform the calculation may need to be assigned more responsibility over the measuring work. In addition, the follow-up work must be envisaged in the long term, which means that the number of registers should be sufficient to distinguish the different parameters, that consumes energy, apart to make it possible to learn from the over-/underestimation, and base future input and standard values on it. This may mean that the simulation-/measure-work should not be limited only to comply with applicable laws, but it should be ensured that follow-up work can be done in such a way that it helps to improve the future work of simulations and measurements of energy use in buildings.
Specifik energianvändning, energiprestanda, energisimulering, energiuppföljning, BBR