Evaluation of a mixed method approach for studying user interaction with novel building control technology

Energy-efficient building performance requires sophisticated control systems that are based on realistic occupant behaviour models. To provide robust data for the development of these models, research studies in real-world settings are needed. Yet, such studies are challenging and necessitate careful design in terms of data collection methods and procedures. This paper describes and critiques the design of a mixed methods approach for occupant behaviour research. It reviews the methodology developed for a longitudinal study in a real-world office environment where occupants’ experience with a novel facade technology (electrochromic glazing) was investigated. The methodology integrates objective physical measurements, observational data and self-reported experience data. Using data from one day of the study, this paper illustrates how the different sources can be combined in order to derive an in-depth understanding of the interplay between external daylight conditions, characteristics of the facade technology, occupant interaction with the technology and the resulting occupant experience. It was found that whilst the individual methods may be affected by practical limitations, these can be partially offset by combining physical measurements and observations with self-reported data. The paper critically evaluates the individual techniques, as well as the benefits of their integration and makes recommendations for the design of future occupant behaviour studies in real-world settings

Variation of indoor temperatures and heating practices in UK dwellings

The UK government is committed to making significant reductions in CO2 emissions by 2050. To meet this target, a considerable reduction in energy consumption will be required from domestic dwellings and, in particular, space heating, which accounts for more than 50% of the energy used in the UK housing stock. Temperature monitoring studies in the UK have been undertaken, these can inform modellers of the variation in indoor temperatures throughout the housing stock. This information will allow energy modellers to better predict the indoor temperatures demanded by household occupants, and consequently improve the accuracy of energy predictions. This paper presents preliminary results from a large-scale city-wide survey of over 500 homes in Leicester, UK. Temperature measurements were recorded at hourly intervals in over 300 homes. Household data, including socio-demographic information, were collected for each household. This dataset is used to investigate the relationship between indoor temperatures and house type. The results confirm that house type is related to differences in indoor temperatures, but this relationship is not significant during heated periods. Further analysis is ongoing to identify how other social and technical factors relate to indoor temperatures

Understanding occupant heating practices in UK dwellings

The 2008 Climate Change Act has committed the UK government to reduce CO2 emissions by 80% of 1990 levels by 2050. To meet this target a significant reduction in energy consumption will be required from domestic dwellings and in particular space heating which accounts for more than 50% of the energy used in the UK housing stock. The UK government has initiated a number of policies to reduce energy use from UK dwellings. Energy savings that result from energy efficiency improvements to dwellings have sometime been lower than expected as a result for the rebound effect. Discussion of the rebound effect has questioned whether these polices will result in the CO2 reductions required to meet the national targets. Large-scale survey research has shown that energy use is related to climate, built form of properties, efficiency of heating systems, socioeconomic indicators and occupant behaviour. Temperature monitoring studies have been undertaken to gain insight into how occupants heat their homes. If the variation in indoor temperatures can be explained by; (1) social determinants such as age, income and the number of household occupants and; (2) technical determinants such as house type, house age and level of insulation then this would enable energy efficiency initiatives (e.g. cavity wall installation or education programmes) to be targeted where they will be most effective. This paper presents preliminary results from a large-scale city-wide survey of over 500 homes in the city of Leicester, UK. Temperature measurements were recorded at hourly intervals over a nine month period for the living room and main bedroom spaces in over 300 homes. Household data, including socio-demographic information, was collected for each household. This dataset is used to investigate indoor temperatures across house types. The results confirm that house type is related to differences in indoor temperatures. Flats have the highest average temperatures while detached homes have the lowest. To gain insight into heated periods households with average evening temperatures were identified. It was found 45% of mid terrace properties had evening temperatures below 18°C and more than a third of detached and semi detached home also had cold evening temperatures. There are a number of reasons for low indoor temperatures in dwellings during occupied periods including inefficiency of buildings and heating systems, the inability of occupants to afford heating and personal choice. It is concluded that to meet Government CO2 reduction targets the rebound effect should be taken into account when calculating the energy savings expected from energy efficiency programmes. Further analysis is ongoing to identify how other social and technical factors relate to indoor temperatures. Multiple regression analysis will be used to identify how internal temperatures are correlated against a number of determinants including building characteristics (built form type, age, heating system type, heating controls) and household characteristics (age of occupants, income)

Does the age of the residents influence occupant heating practice in UK domestic buildings?

The UK Government is committed to reducing CO2 emissions by 80% of 1990 levels by 2050. To meet this target significant reductions in energy consumption are required from the UK housing stock. Space heating is the most significant end use of energy in residential buildings. Behaviour that relates to the direct interaction of residents with heating systems is termed occupant heating practice (OHP). More empirical evidence is required to determine if OHPs relate to socio-demographic and economic status of households. Improved knowledge of OHP will aid policy makers in successfully targeting energy efficiency measures. To build the evidence base for OHP, a large-scale city-wide housing survey was carried out in Leicester, UK in 2009-2010. Internal temperature measurements and details about household composition were collected in over 300 dwellings. These data are used to explore the links between OHP and the age of occupants. Results of the initial analysis suggest that older occupants demand higher living room temperatures but may heat a lower proportion of their dwelling. 36% of dwellings were observed to have lower than average temperatures. Continued analysis is required to find out if energy efficiency measures could improve the thermal comfort of occupants or if low temperatures are a result of short daily heating periods. A more detailed monitoring study is required to investigate the variation in internal temperatures throughout dwellings and to gain further insight into OHP

Measurement and analysis of household carbon: the case of a UK city

There is currently a lack of data recording the carbon and emissions inventory at household level. This paper presents a multi-disciplinary, bottom-up approach for estimation and analysis of the carbon emissions, and the organic carbon (OC) stored in gardens, using a sample of 575 households across a UK city. The annual emission of carbon dioxide emissions from energy used in the homes was measured, personal transport emissions were assessed through a household survey and OC stores estimated from soil sampling and vegetation surveys. The results showed that overall carbon patterns were skewed with highest emitting third of the households being responsible for more than 50% of the emissions and around 50% of garden OC storage. There was diversity in the relative contribution that gas, electricity and personal transport made to each household’s total and different patterns were observed for high, medium and low emitting households. Targeting households with high carbon emissions from one source would not reliably identify them as high emitters overall. While carbon emissions could not be offset by growing trees in gardens, there were considerable amounts of stored OC in gardens which ought to be protected. Exploratory analysis of the multiple drivers of emissions was conducted using a combination of primary and secondary data. These findings will be relevant in devising effective policy instruments for combatting city scale green-house gas emissions from domestic end-use energy demand

The carbon footprint of UK Cities: 4M: measurement, modelling, mapping and measurement

The carbon footprint of UK Cities: 4M: measurement, modelling, mapping and measuremen