The project aim was to develop knowledge about the energy performance of different door solutions. The door types that we have focused on are automatic sliding doors and revolving doors. Losses through a door depend on its U-value, infiltration leakage through the seal when closed and unintended air exchange when the door is open and in use. It is the last factor, the unintended air exchange when in use, which is mostly addressed in this report and it is also the most significant part when it comes to energy losses through entrance doors.

To achieve environmental targets, energy use in buildings must be reduced. There is a gap regarding knowledge about the energy losses through the entrances and how it affects the total energy use of the building. The problems regarding entrances are neglected in calculations of low energy buildings, even though they in many cases may have a large impact on the energy use. Meanwhile, the unintended air exchange through the doors is a parameter that has a large uncertainty and that is difficult to predict in energy calculations. To achieve a better accuracy in calculated energy performance, better methods and estimations regarding the unintentional air exchange through the entrances is needed.

In the project we measured air exchange rates through a revolving door and investigated the effect of temperature difference and door rotation speed in our laboratory, based on a reduced scale revolving door with the scaling 1:2.  Both temperature measurements and tracer gas measurements were performed, and the temperature measurements gave more stable results. The measured air exchange rate was affected more by the door rotation speed than the temperature difference, within the measuring ranges that was tested.

Further, we have also analyzed and applied existing calculation models for entrance doors. Calculations for estimating the energy losses for a door was made for a simple case study of an office building in Gothenburg, based on a number of different calculation models for sliding doors and revolving doors. The calculation results for this specific study show that the revolving door can prevent up to 60-90% of the losses compared to a sliding door depending on which air flow scenario, i.e., single sided- or cross ventilation, is considered for the sliding door. Better knowledge is needed to understand the actual air flow profile of real cases when the sliding door is installed in a building. Furthermore, additional studies are needed for the revolving door to ensure the results from this study by e.g., extended laboratory measurements and also field tests. Also, how other parameters such as wind (magnitude, direction and incidence angle) and door usage affecting air exchange through a revolving door is needed to be investigated further. Next step to develop a reliable model for revolving doors is to repeat the measurements performed in this project on a full scale revolving door and with a larger test range.