Improving the ventilation in passive house swimming pool: A case study of Åfjord swimming pool

The importance of satisfactory air quality and thermal comfort are continuous scientific research regarding energy efficiency and health in swimming pool. Thisstudy aims to improve the ventilation efficiency in passive house swimming pools with respect to the air quality for swimmers and thermal comfort. Numerical simulations are performed with computational fluid dynamics CFD methodology for this. The CFD model in this work is based on the swimming pool under construction (Åfjord swimming pool) located in centeral Norway. Multi-component compressible Navier-Stokes system of equations together with turbulence models are solved for this. The evaporation of water from the pool surface are modelled based on the ASHRAE Shah phenomenological model. The multi-component gas mixture consists of water vapour, chlorine and air. Surface to surface radiation models are also considered to include the effects of radiation inside the swimming pool. Five different ventilation strategies are investigated e.g., mixing ventilation (MV), mixing ventilation-displacement ventilation (MV-DV), and three more displacement ventilation (DV4, DV5 and DV7) cases with different air change per hour (ACH). These three cases are considered as conventional DV strategies in swimming pool. The results confirm that the MV case can be a highly recommended option to use in Åfjord swimming pool. For this case, due to the indicator for air quality with local mean age of air (LMA) there are no stagnant air regions inside the swimming pool. Also, due to the air exchange efficiency indicator (ACE) this system exchange the air similar to "piston mode" ventilation. Furthermore, the air quality in the swimming pool is clearly improved and there is no sign observed for condensation risk. The thermal comfort is considered as accepted. Worthy reduction in operation expenses is strongly expected for this system. The analysis of MVDV case reveals that, it is highly recommended to use especially during the winter time when the heat demand is high. This system shows the best performance in order to reduce the chlorine concentration near and above the water bath. This system exchange the air with intermediate efficiency similar to "fully mixing" ventilation according to the ACE measurements. It also shows good thermal comfort due to stable air temperature, low air velocity and good air humidity level. In case of DV, we found a poor performance to reduce the chlorine concentration swimming breathing zone. Furthermore, It can also be concluded that, the chlorine concentration reduction is negligible with the increase in ACH for DV cases with conventional strategies