BSER&T Special Issue, March 2015: Overheating and indoor air quality
Increasing temperatures caused by climate change and intense urbanisation are already causing problems of overheating and reduced indoor air quality (IAQ) in some buildings, especially during the warmer periods of the year. Such problem will potentially intensify in the future, especially in cities where conventional cooling measures such as shading and opening windows would be insufficient given the levels of pollution, noise and security concerns. There is a need to consider the effects that highly insulated and airtight spaces will have on IAQ and thermal comfort as current focus in buildings is on their winter performance in order to reduce heat losses.
The current issue of Building Services Engineering Research and Technology journal was commissioned by the Adaptation and Resilience in the Context of Change (ARCC) Network (http://www.arcc-network.org.uk/) with the aim to present the latest research on overheating and IAQ risks in buildings. There are nine papers published in the SI looking at different aspects of the issue for various building types, including homes, hospitals, schools and offices. There are several key messages highlighted by all papers, useful for both industry and policy professionals.
Unintended consequences of energy efficiency; reducing infiltration rates without an appropriate, ventilation strategy could have a negative effect on thermal comfort and IAQ. On the other hand increased ventilation in highly polluted areas, such as urban centres, could cause health problems to occupants. The research highlights the complexity of achieving healthy indoor environments while at the same time meeting energy efficiency targets. Ventilation is central to a healthy indoor environment, but careful consideration is needed – optimal ventilation rates will vary by building type, occupancy and type of use, location, orientation, etc.
Future performance of buildings; indoor thermal comfort and IAQ will diminish in the future unless building design practices address the issue now. Furthermore, not planning for future overheating could lead to a new energy gap. The UK will need to adapt to a changing electricity demand for cooling in the future, as more buildings, especially in the southern regions, will require some type of mechanical cooling by the 2050s.
Recommendations for addressing the issue; most of the research presented at the SI examined various solutions and strategies to tackle overheating and IAQ, and the consistent message is that at some point in the future, no passive and/or occupant behaviour measure will be sufficient to provide an acceptable indoor environment, even for buildings that are now performing well. The studies that looked at both thermal comfort and IAQ agree that the interrelationship between indoor temperatures, IAQ and energy consumption will result in trade-offs when interventions are considered, and they have highlighted the need to investigate strategies in order to fully understand the unintended consequences.
The above key messages are highlighting the importance of considering occupant comfort, health and well-being as a priority in the design of buildings. In order to achieve this, a holistic approach to performance analysis needs to be implemented where indoor thermal comfort and air quality are investigated throughout the year.
Written by Dr Anastasia Mylona, Research Manager, CIBSE
For more information download the Overheating and Indoor Air Quality journal, free to CIBSE members.