A new Passivhaus municipal swimming pool for the City of Exeter
The building project is the design and build of a new state of the art indoor municipal pool facility in Exeter, including a main National/County standard swimming pool and a learners' pool with supporting facilities together with dry sports facilities. The project evaluated various design options for three potential sites in the centre of Exeter in relationship to climate change risks to inform the selection of the most appropriate site to locate a new state of the art Indoor Public Municipal Pool Facility for Exeter. Advantages and disadvantages with regards to thermal comfort, water management and impacts on construction under future climate scenarios have been analysed as part of this study.
The following key areas were assessed using IES dynamic modelling and the PHPP (Passive House Planning Package):
- Building Orientation
- Single sided ventilation vs. cross flow ventilation
- Construction strategies – heavy weight, medium weight, light weight
- Intelligent ventilation control – windows closing when external air temperature is hotter than inside
- Solar shading strategies
- Zoning to reduce internal gains and minimise energy losses
- The role mechanical ventilation heat recovery (MVHR) can play to support passive ventilation strategies in a mixed mode approach
- The role of MVHR coupled with ground cooling
The results from this study indicate that the wet areas of a pool require heating almost all year round even under future climate scenarios. Selecting a site and window design that enabled south facing orientation allowed for an optimum balance of heating and cooling requirements for current and also future climate scenarios. At the same time the relative humidity settles at around 65% in the pool hall offering dehumidification energy savings which result in lower air change rates, lower fan power, lower energy loads on evaporative cooling/ dehumidification systems and also generate considerable water savings. However, it is important that the optimum Relative Humidity (RH) is realised for both users’ comfort and to protect the fabric of the building. Thermal bridge free detailing further reduces the condensation risk and helps protect the building fabric.
The dry sports and admin areas are prone to overheating and benefit from a north facing orientation and thermal separation from the pool area through careful zoning and layout. Implementing cross ventilation and ground cooling further reduces the risk of overheating for these areas. The water consumption will be considerably reduced by implementing the low water use, filtration, water re-use strategies and strategies to reduce evaporation from pool water.
Incorporating Passivhaus principles results in approximately 5% cost increase when compared to 2010 building regulations envelope base case. It was found that the Passivhaus design saved £60,000 a year in energy for space heating alone, equivalent to a payback period of 10 years.
More up-to-date information and regular updates on this project can be found here.