Building Performance - Methods for Improved Prediction and Verification of Energy Use and Indoor Climate

Detta är en avhandling från Byggnadsfysik LTH, Lunds Tekniska Högskola

Sammanfattning: Reducing CO2 emissions is one of the most important goals in Europe as well as the rest of the world. To reach that goal, the use of energy must be reduced. Thus, the building industry is facing a great challenge. Not only energy efficiency but also sustainability is desirable in the building stock. This thesis presents and suggests methods that can be used to improve prediction and verification of building performance regarding energy use and indoor climate. Predictions of energy use and indoor climate generally do not agree with results from measurements in buildings during operation. These discrepancies are counter-productive to the implementation of energy-efficiency and sustainability measures. This thesis addresses these issues and suggests viable partial-solutions to the problems encountered. This research project has measured several energy use and indoor climate related parameters in multi-family buildings in Sweden. The monitoring was frequent, at least once per hour, and the measurements lasted at least one year, which makes it possible to present reference data for the measured parameters and their variations on different time scales and during different conditions. Based on the analysis of the measurements, several methods offering partial-solutions on different levels to the addressed problems have been developed. Examples of these methods are: • A method to assess useful solar heat gains in actual buildings during operation. • A method to assess window airing and air leakage in actual buildings during operation. • A method to assess occupancy level in actual buildings during operation. • Methods to generate hourly input data on hygrothermal conditions that take into account both outdoor conditions and user behaviour. • A method to make meteorological corrections to energy use that takes into account several outdoor climate parameters and the characteristics of the building concerned. The methods aim to describe reality more accurately and can be applied to predictions and verifications. The methods are fully developed and ready to use in practice. These methods together with the discussion and argumentation in this thesis provide the building sector with useful and positivistic recommendations. If these are used, it is believed that it will be possible to increase the quality of predictions and verifications, and agreement between them, as well as to provide buildings displaying increased sustainability, with low energy use and good indoor climate.