The operation of a typical indoor swimming pool is very energy intensive. Previous studies have shown that high quality thermal building envelopes, i.e., with high levels of insulation and airtightness, make it possible to rethink conventional ventilation concepts. Due to the reduced condensation risk in and on envelopes of high thermal quality, ventilation design can be optimized for indoor air quality rather than for averting condensation on the facade. This work investigates different air distribution concepts for an existing swimming pool via computational fluid dynamics (CFD) simulations to evaluate their ventilation efficiency. To reduce modelling and computational resources, the velocity and turbulence fields produced by the swirl-diffusers are determined in a set of separate CFD simulations and incorporated into the swimming pool models. The results show that the ventilation efficiency in the examined swimming pool could potentially be improved with various alternative air distribution concepts, therefore improving the indoor air quality. Although the results seem plausible and compare well with the limited measurement data of air humidity, a more formal experimental validation is still needed before generalizing recommendations.

This paper reports the results of an interview survey conducted among different stakeholders involved in design, installation and operation of residential ventilation in seven European countries. In total 44 interviews were performed. The results provide a valuable snapshot of current practices and insights into potential barriers and challenges regarding installation of mechanical ventilation in low-energy residences to maintain high indoor air quality (IAQ). The results show that mechanical ventilation with heat recovery is becoming a common choice in new low energy residences in Europe. However, there are countries that apply airing or other types of ventilation such as mechanical exhaust or natural ventilation due to tradition, national legislation, climatic conditions and/or cost reasons. Demand-controlled ventilation (DCV) is often allowed or even recommended in standards, but rarely implemented in practice, except for exhaust-only humidity-based DCV in France and Belgium. The main barriers against mechanical ventilation seem to be high capital cost, space requirements and duct routing. The respondents commonly reported problems resulting from poor construction, lack of commissioning and/or maintenance. The main needs to be identified in the survey were more legislative pushes including more flexibility in legislation, a coordinated approach to energy efficiency and IAQ, and control mechanisms to ensure good implementation and operation.