Sensitivity analysis concerning the design of the building envelope and the HVAC system of apartment buildings

The technology of today could halve the building energy consumption, which stands for 40% of Europe's total energy consumption (Elmroth, A. 2006). This would imply lower operating costs but also contribute towards a better environment. This report attempts to give a general and lucid picture on how different designs of the building envelope and HVAC systems affects the energy consumtion in an apartment building with tenant-ownership. The analysis also includes environmental aspects and economy in a lifecycle perspective. By simulating an apartment building in the computer program IDA Climate and Energy and studying each individual alternation of the building separately it was possible to show the effect in energy consumtion versus a standard case. Examples of studied factors are insulation thickness, windows, thermal bridges and user behaviour. Sensitivity analysis of other affecting factors has also been performed. The HVAC system and source of energy for heating are important factors for how the energy consumtion affects the environment. This study compares different alternatives to show how they affect the environment regarding global warming, particle emissions, photochemical ozone formation, acidification and euthrophication. The environmental study gives the building's environmental influence during one year. An economical analysis of different investment alternatives for reducing the reference building's energy consumtion and environmental influence have also been made. This study analyses which of the alternatives that is he most profitable in a life cycle cost perspective. The simulation results show that windows are the most important factor in the building envelope in an energy perspective. Changing windows can save up to 9 kWh (m2 . year)comparing to the reference building. But changing windows is not motivated in an econimical perspective according to the LCC analysis. The most important HVAC-factor in an energy perspective is the usage of the heat recovery of the exhaust air which in this study would save 27 kWh (m2 . year). Other important factors for reducing energy consumption are indoor air temperature, ventilation system design and actual hot water usage