Abstract
Purpose: The purpose of this study was to examine the energy savings by replacing windows from existing 2-glazed windows to a new 3-glazed windows for a specific apartment in a specific apartment building in Botkyrka. In the major renovation project, no consideration was given to windows which are an important part of the building in terms of energy. Method: The method was to study the home and the associated floor plan was carried out to get an idea of the different orientation of the windows, but also to perform measurements. It formed the basis for the energy calculations that were made to analyse the energy use for the need of heating. And with that calculate the energy use for heating for each month for an entire year with the existing 2-glazed window and then compared with the energy use for the 3-glazed window. Results: The result shows an energy saving of 17%. That result is judged to be quite typical for apartment buildings from the million program. Conslusions: The conclusion that can be drawn from the work of this project is that the investment is profitable as it is compared with the annual savings for energy use for heating. It is the replacement of old windows that actually have a remaining life. In practice, it is difficult to do so with good profitability because a very large investment must "pay" a rather limited annual saving.
Keywords: windows, energy efficiency, energy use and heating.