Thermal comfort in UK Homes: how suitable is the PMV approach as a prediction tool?

This thesis presents a body of work conducted in the field of domestic thermal comfort. The aim of this research was to determine the suitability of the Predicted Mean Vote (PMV) index in homes within the UK. Two field studies were conducted with a sample of participants living in owner occupied properties in a UK city (London) and a UK provincial town (Loughborough). Research findings indicate that the PMV is indeed a good predictor of thermal sensation in homes when conditions are steady state and people are engaged in near-sedentary activities. When conditions are not steady state and people are engaged in a variety of household activities, the accuracy of the PMV index can be improved by using a metabolic rate coefficient of 1.7. Further research work is required to ascertain this and likewise the range of applicability of the Adaptive Model

Project CALEBRE: Consumer Appealing Low Energy technologies for Building REtrofitting: a summary of the project and its findings

Project CALEBRE ‘Consumer-Appealing Low Energy technologies for Building REtrofitting’ (October 2008 – April 2013) was a £2 million E.ON / RCUK-funded research project comprising a partnership of six leading UK universities, and supported by a Project Advisory Board. Our aim was to contribute to addressing the challenge of reducing UK domestic energy demand and carbon emissions. With our focus largely on solid-wall, ‘hard to heat, hard to treat’ dwellings, we investigated a selection of current, medium and longer-term technologies for domestic energy efficiency refurbishment, with householder perspectives at the heart of our thinking. We approached this from a multi-disciplinary perspective, encompassing a range of techniques that included laboratory testing, simulation modelling, test house field trials and user engagement methods

Measured winter and spring-time indoor temperatures in UK homes over the period 1969-2010: A review and synthesis

This paper presents a review and synthesis of average winter and spring-time indoor temperatures in UK homes measured over the period 1969-2010. Analysis of measured temperatures in a sample of solid wall dwellings in the UK, conducted as part of the CALEBRE research project, is included. The review suggests that, for periods when occupation was likely, there has been little or no increase in winter and spring-time average living room temperatures over the last 40 years, with average recorded living room temperatures having been historically lower than the WHO-recommended value of 21. °C. Correspondingly, for periods of likely occupation, average bedroom temperatures appear to have increased. Compared with non-domestic buildings, there have been fewer investigations of domestic thermal comfort, either in the UK or elsewhere, and hence the paper also calls for further detailed investigations of domestic indoor temperatures during occupied hours together with thermal comfort evaluations in order to better understand domestic thermal environments. Based on suggestions from the limited range of studies available to date, living room temperatures may need to be maintained within the range 20-22. °C for thermal satisfaction, though this requires confirmation through further research. The study also emphasises that improving the energy efficiency of homes should be the primary means to effect any increases in indoor temperatures that are deemed essential. Considerations for future policy are discussed. © 2013 Elsevier Ltd

Identifying a suitable method for studying thermal comfort in people’s homes

In the UK, domestic buildings are responsible for a significant amount of overall carbon emissions from buildings. Together with improving the energy efficiency of the existing domestic stock, an in-depth understanding of thermal comfort in homes is necessary to ensure that acceptable levels of thermal comfort are maintained whilst energy use is being reduced. Currently, there is limited knowledge on domestic thermal comfort in the UK as, compared to non-domestic buildings, conducting thermal comfort studies in homes is challenging. Detailed thermal comfort studies are usually considered to be intrusive in domestic environments. Is it therefore possible to conduct thermal comfort studies that are less intrusive and yet scientifically rigorous? With a view to address this question, the study presented in this paper undertook a comparison of two data collection methods. Data collected using a less-intrusive method, referred to as the ‘Silver standard’ was compared with the data collected using the ASHRAE/ISO recommended method (referred to as the ‘Gold standard’). A strong correlation was observed between PMV values obtained using the Silver Standard method and those obtained using the Gold Standard method. The findings suggest that the less-intrusive method devised and tested in this study provides reliable data for thermal comfort evaluations in homes. The findings also suggest that further work is necessary, particularly in winter conditions to comprehensively validate this non-intrusive method

Assessing the ability of PMV model in predicting thermal sensation in naturally ventilated buildings in UK

A study was conducted to investigate the accuracy of the PMV model for predicting thermal comfort sensations in naturally ventilated residential and office buildings in the UK. Sixteen participants participated in identical thermal comfort studies at both their homes and their offices. Environmental variables affecting thermal comfort were recorded while the participants voted their thermal sensation in both locations. The comparison of reported thermal sensation and those predicted using ISO 7730 showed that in general PMV under predicts the thermal sensation of occupants in both environments. The neutral temperatures found in homes and offices were 23.4ºC and 23.2ºC which were respectively 3ºC and 2.5ºC lower than those predicted using ISO 7730. Together with 0.2ºC difference found between reported neutral temperatures at homes and offices, this suggests that there could be a context influence affecting occupants’ thermal sensations in home and office environments

UK solid-wall dwellings - thermal comfort, energy efficiency refurbishment and the user perspective - some preliminary analysis from the CALEBRE project

The paper discusses the state of solid wall housing in the UK, and the technical and socio-economical challenges that need to be addressed whilst refurbishing this stock. The challenges of improving the thermal performance of the envelope and of reducing space heating-related carbon emissions in solid wall housing are discussed together with issues related to thermal comfort, the ‘take-back’ process and user-appeal. Preliminary results of the Householder Survey of Project CALEBRE are presented, including the sample selection and survey processes. It is concluded that, irrespective of cost factors, the perceived benefits and aspirational appeal of carbon-reducing technologies need to outweigh the cost associated with disruption from the perspective of the householder. Achieving this, places demanding requirements not only on technologists and designers but also upon those responsible for marketing essential energy saving solutions

Improving the airtightness in an existing UK dwelling: the challenges, the measures and their effectiveness

Air infiltration, occurring through gaps in the building envelope, can contribute up to one third of total heat losses associated with older UK dwellings [1]. Therefore, reducing the rate of air leakage (i.e. improving air ‘tightness’) can have a positive effect in terms of decreasing space heating requirements. This study presents an investigation of the effectiveness of airtightness measures applied in a retrofit context to a UK dwelling. A phased programme of refurbishment work was undertaken to a test dwelling at the University of Nottingham campus, UK. Evaluation techniques, including building energy modelling (SAP 2009), air pressurisation tests and thermal imaging, were performed. The study demonstrates that the use of conventional draught-proofing measures can achieve a reduction in air permeability of over 30% when compared with the house base case value of 15.57 m3/(h.m2) @ 50 Pa. This reduction was only achievable with close attention to installation detail. Further measures of service penetration and floor sealing enabled the air permeability to be reduced to as low as 4.74 m3/(h m2) @ 50 Pa. Modelling of the test dwelling predicted an initial space heating supply energy requirement of 32,373 kWh, which was reduced to 23,197 kWh by a combination of the air tightness measures, insulation, and system (boiler and ventilation) improvements. Air tightness measures alone contributed to approximately 9% of the predicted total reduction, half of which was due to relatively straight-forward draught-proofing. Other more advanced air tightness measures were considerably more expensive, though cheaper approaches to their application could help reduce payback times

The 100 day challenge: a literature review of the factors associated with tackling fuel poverty in the UK

Fuel poverty is a complex issue arising from a simple problem: the inability to afford to sufficiently heat one’s home. The Government has pledged that all vulnerable households should be removed from fuel poverty by 2010, with longer-term aims that no households in England should live in fuel poverty by 2016 and that, by 2018, fuel poverty should be completely eradicated throughout the UK . This report comprises a review of the available literature on the major issues associated with fuel poverty in the UK, with particular reference to the efficacy of staple methods used to treat fuel-poor households

Refurbishing the UK's 'hard to treat' dwelling stock: understanding challenges and constraints

Project CALEBRE (Consumer Appealing Low Energy technologies for Building REtrofitting) is a four year £2 million E.ON/RCUK funded project that is investigating technologies and developing solutions for the UK’s solid-wall houses to offer energy demand reduction, energy efficient heat generation and energy management combined with user appeal. Understanding how technical solutions can be aligned with householder lifestyles is central to the CALEBRE project. The technologies include: vacuum glazing to achieve exceptionally low U-values whilst being capable of retrofit in existing window frames; advanced gas and electric air source heat pumps that operate at the temperatures needed for integration with existing domestic radiator systems; innovative surface materials for buffering moisture, humidity and temperature; retrofit mechanical ventilation with heat recovery (MVHR) to manage ventilation and its associated heat loss. The technologies are being trialled in facilities that include the University of Nottingham E.ON 2016 House, a highly instrumented replica construction of a1930s dwelling. Alongside development and trialling, business case modelling of technologies is being conducted to establish mass roll-out strategies, as well as modelling to identify bespoke packages of measures for house refurbishment. This paper introduces Project CALEBRE, its content and scope, and reports some of its initial findings to highlight the challenges and constraints involved in the process of refurbishing the UK’s domestic stock