Thermal Comfort, Control and Energy Use

Abstract

The theory of adaptive thermal comfort has radically changed our understanding of thermal comfort and its application in naturally ventilated and hence more sustainable buildings. Field studies have allowed to consider psychological and behavioural aspects, which were ignored in the traditional PMV/PPD model. The models derived from the adaptive theory (EN 15251 and ASHRAE-55) provide practitioners with a linear relationship relating indoor comfort temperatures with outdoor temperatures, which has the advantage of being easily understandable and applicable. However, a number of limitations exist in both the theory and application of the adaptive hypothesis. In this thesis, we identify these limitations and address them. Firstly, the current models reduce the adaptive hypothesis to a linear relationship between the indoor comfort temperatures and the outdoor temperatures, hence excluding all other variables. This seems to militate against the well-known physiological impacts of variables such as air humidity and air velocity. Using global thermal comfort field data, this thesis demonstrates for the first time that air humidity has a significant effect on occupant thermal perception. This result is then cast into a new model of adaptive comfort that allows practitioners to design naturally ventilated buildings in a variety of temperature-humidity contexts. Secondly, the traditional adaptive models claim validity over a wide range of geographic and climatic locations, included some from which no empirical data were derived, as well as applicability in a range of building categories (e.g. residential, educational) despite primarily being derived from office buildings. This thesis thus investigates whether the EN 15251 adaptive model, derived principally from data collected in non-UK office buildings, is able to predict thermal comfort of British residential occupants through comparison against field data collected in UK homes. Results demonstrate that the European adaptive model underestimates thermal discomfort of British residential occupants. Finally, this thesis investigates whether perception of control, which is known to affect the adaptive response of occupants, impacts the ability to drive behavioural change through occupant feedback – a major part of the smart meter roll-out across the world. Results from a field study demonstrate that real-time and context-aware feedback could contribute to an increase in occupant perceived environmental control while prompting lower heating energy behaviours.

Date of Award	10 Nov 2017
Original language	English
Awarding Institution	University of Bath
Supervisor	Sukumar Natarajan (Supervisor) & Ian Walker (Supervisor)