On Design Principles and Calculation Methods Related to Energy Performance of Buildings in Finland

OF DOCTORAL DISSERTATION HELSINKI UNIVERSITY OF TECHNOLOGY P.O. BOX 1000, FI-02015 TKK http://www.tkk.fi Author Juha Jokisalo Name of the dissertation On design principles and calculation methods related to energy performance of buildings in Finland Manuscript submitted 20.5.2008 Manuscript revised 11.9.2008 Date of the defence 28.11.2008 Monograph Article dissertation (summary + original articles) Faculty Faculty of Engineering and Architecture Department Department of Energy Technology Field of research HVAC-technology Reviewers Professor Antero Aittomäki, Tampere University of Technology, Finland Professor Li Shao, De Montfort University, UK Opponents Professor Li Shao and D.Sc. (Tech.) Pekka Tuomaala, VTT, Finland Supervisor Professor Kai Sirén, Helsinki University of Technology, Finland Instructor Docent, D.Sc. (Tech.) Jarek Kurnitski, Helsinki University of Technology, Finland Abstract The EU has set the energy performance directive for buildings (2002/91/EC) in order to decrease CO2 emissions by increasing the energy performance of buildings. This directive states that the energy efficiency of buildings has to be calculated in the member states. The main objective of this thesis is to support the implementation process of this directive in Finland. This thesis focuses on the adaptation and development of simplified calculation methods related to the energy performance of buildings and on the development of design principles in order to improve the energy performance of buildings. The energy performance of buildings depends on several factors that are related to building fabric, HVAC systems, indoor and outdoor climate and behaviour of occupants. In this thesis, the studied factors are balanced ventilation system, electrically heated windows, thermal inertia of building structures and infiltration of building envelope. The effect of these factors on energy performance of buildings was studied mostly using a dynamic simulation tool IDA-ICE. In order to calculate the energy efficiency of buildings, calculation methods are needed that are sufficiently applicable and accurate. The monthly utilisation factor heat demand calculation method EN ISO 13790 can be calibrated for Finland regarding the effect of thermal inertia of building structures. The calibrated monthly method can be used for residential buildings, but should not be used for office buildings in Finland. Therefore, more-detailed dynamic methods should be used in the calculation of the energy performance of office buildings. Infiltration rate depends on several factors and calculation methods that are not able to take these factors into account explicitly should be adapted at a national level. The simple adapted infiltration model that was developed in this study, can be used to approximate the average infiltration rate of detached houses in Finland. But, dynamic building simulation with a multizone infiltration modelling is a reasonable choice for detailed infiltration and energy performance analyses.