Thermal comfort in non-uniform environments: real-time coupled CFD and human thermal-regulation modelling and validation
Francesco Babich, Loughborough University
Buildings contribute more greenhouse gas emissions than either the industrial or transportation sectors, primarily due to space cooling and heating energy use, driven by the basic human need for thermal comfort and good indoor air quality. There has been a proliferation of air-conditioning in both residential and commercial buildings, and this trend is likely to increase with global warming.
Although many previous projects have addressed aspects of thermal comfort, there are only a few studies focused on asymmetrical environments or transient conditions, such as those expected with mixed mode ventilation. Focusing on non-uniform thermal environments is important because the space conditioning systems that generate them are often likely to be less energy consuming than those which provide more homogeneous conditions.
The aim of the current research is to develop a better understanding of human thermal comfort in domestic buildings and to improve the capability of prediction of human thermal comfort in domestic buildings.
One main research hypothesis will be investigated, that thermal comfort in residential buildings characterised by asymmetrical environments or transient conditions can be effectively and efficiently predicted using suitable models.
This PhD project is linked with a wider research project that involves Loughborough University (UK), University of California Berkeley (USA), CEPT University Ahmedabad (India) and De Montfort University (UK), entitled “Reducing global energy use in buildings while improving occupant comfort and well-being: reversing the growing trend toward energy-intensive air-conditioning”. Its main investigators are Professor Cook and Professor Loveday.
An extensive literature review will be conducted in the early stage of this research to better define the knowledge gap to be addressed by the proposed project and also to acquire more and detailed information about the methodology that previous researchers have adopted. In order to achieve its aim, this research project will then follow four key stages of work.
Firstly, 5 to 20 UK households will be recruited to take part in a field study over both winter and summer. Physical measurements of air temperature, relative humidity and mean radiant temperature will be taken and, to assess thermal comfort, participants will be asked to complete a number of thermal comfort surveys to assess their perceived thermal comfort.
Secondly, a model of domestic mixed mode ventilation will be developed using both computational fluid dynamics (CFD) modelling and dynamic thermal modelling. An existing coupled model of indoor air flow and thermal comfort will be used to predict thermal comfort, airflows and indoor air quality. This model has been developed by Cropper et al (2010) and uses the IESD-Fiala model of human thermoregulation and a commercial CFD code. Dynamic thermal simulations will be performed for comparing the use of traditional air-conditioning with these less energy consuming techniques.
Thirdly, an environmental chamber will be used to validate the model developed in stage two. As a consequence, the second and the third stages are likely to be iterative in nature.
Finally, this research will have a wider application, expanding its impact beyond the UK. Indeed the model will be tested with data from both India and the USA. It will also be integrated with other low-energy techniques in other climates where appropriate
In general, it is intended that this research will lead to proposals for revisions to existing international standards concerning thermal comfort with the aim of reducing the use of energy-intensive air-conditioning, and promoting these innovative, lower energy approaches for heating, cooling and ventilation.
This poster gives an insight of my MRes project, which was about the performance of ventilation cooling towers in plus-energy houses.
At the “4th Masters Conference: People and Buildings”, the presentation by LoLo student Francesco Babich about his MRes project was voted the best joint presentation by the audience. The conference was held at Central House, The CASS, London on 19th September 2014.