UK Current Development and Future Prospects

Currently, most modern timber houses in the UK are constructed with structural timber products and the exterior walls are covered with cladding materials different from structural timber or made from recycled timber. The most frequently used cladding materials in many newly built houses over the last few years are bricks of different kinds for protection against rain and harsh external weather conditions. Structural timber materials are produced outside the UK and brought as off-site products to many sites in the country for assembly. According to figures released by the Office of National Statistics (ONS) and reported in TTF (2014), UK based major timber producers are currently 120 in number with an estimated value of more than £8.5 billion and solid timber market occupies £2.4 billion with overall volume of about 17.1 million/m³. In the last half decade, about 5 to 10 UK based new companies are joining the timber construction sector (Sustainable Homes, 2000). The development has widened the opportunity for the market to grow with many modern publicly and privately financed

49 housing built with prefabricated timber. Some of the prefabricated timber houses built within the last decade in the UK will be considered in Chapter 5. Also, the development has led to improvement in modern methods of construction used for timber houses.

3.6 Summary

This chapter presented an architectural historic overview of UK housing developments in the 20th century (in particular, the 1980s and the 1990s). The design, materials, methods of construction and performance were briefly explained. It appears that the houses are more generous with higher internal floor area, floor-to-ceiling heights and larger size of openings when compared to many newly built houses. In terms of planning, the internal spaces were arranged to avoid having too deep rooms which can possibly enhance natural ventilation of the spaces in summer.

The late 1980s saw a great development of prefabricated timber-framed houses with improvement in the level of insulation to improve the performance of timber-framed houses. The late 1990s saw a move from construction of timber-framed houses to prefabricated structural timber panel houses which have been increasingly built across the UK in the last decade. However, the actual performance of houses built with prefabricated timber panels has not been investigated and it will be discussed in Chapters 6 and 7.

Considering the minimum space standards used over the last few decades in the UK suggest the Parker Morris Standards as a point of reference for other space standards in

the UK’s housing history due to consideration for various need in housing. From pre-

1960s to the current period shows that UK houses are getting smaller with reduced internal floor area of spaces and floor-to-ceiling heights. The consideration of other standards showed that the Developer standards are considerably small and a radical approach needs to be done to improve the size of internal spaces in the UK. Looking at minimum space standards across Europe indicate UK houses as one of the smallest in the continent with lower density per/m² than many nations that build bigger houses.

Finally, the evaluation of current and future developments of prefabricated timber housing on a global scale showed that timber has been widely used for housing developments in many advanced nations with the US as a leading nation in the sector.

50 Considering the UK, it appears timber housing stock is growing rapidly in recent years with estimated value above £8 billion. The current development suggests there is a potential with huge prospects for prefabricated timber housing sector and every effort must be put in place in terms of policy, market strategy and innovative research to focus more on the sector for future improvement.

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Chapter 4 Data Protocol

4.1 Introduction

“The post-occupancy evaluation (POE) of buildings is an increasingly important tool for the improvement of buildings and the evaluation of what makes energy-efficient and sustainable buildings [...]. The science of thermal comfort defines the reproducibility of the human as a thermometer of comfort. The post-occupancy evaluation typically uses this human characteristic as one dimension of its evaluation of a building. Field studies of thermal comfort have shown that the way in which occupants evaluate the indoor

thermal environment is context dependent and varies with time”.

- Nicol & Roaf (2005, pp.338, 344). This chapter presents data protocol and techniques used for the analysis of data. The research procedure and strategy used will be discussed which include identification of UK housing developments built with prefabricated timber materials over the last decade, selection of the case studies based on important parameters such as location, sustainability or low energy rating awards, type of building, access and methods of construction. The development of post-occupancy questionnaire, the steps taken to contact the appropriate authorities in charge of the buildings in order to secure approval to investigate and access the case studies as well as administration of the questionnaire will be discussed. The collection of the questionnaires filled by the respondents will be mentioned.

Physical measurements of the variables in order to assess the environmental conditions of the case studies will be presented. Environmental monitoring is considered to be very important in comfort field studies as it provides information and modifications that can be made in predicting the expectation and feeling of the occupants based on data collected from the measurement of environmental variables (Nicol & Roaf, 2005). The experimental plan for the monitoring will be briefly outlined. The collections of outdoor weather data as well as retrieval of the data recorded by the equipment for analysis will be explained.

52 Comfort surveys which help to understand how indoor occupants interact with the case studies will be examined. The frequency of filling the questionnaire by the participants and minimum hour between administrations of two questionnaires will be mentioned. The collection and collation of the data for analysis will be considered. The comparison between comfort surveys, post-occupancy surveys and environmental monitoring results will be presented in Chapter 6.

The last section of this chapter discusses dynamic thermal modelling and simulation. The software used for dynamic thermal simulation will be mentioned. The sources of outdoor weather data files used for the simulation will be highlighted. The calibration of simulated results and environmental monitoring results will be considered and the details of the results will be discussed in Chapter 7.

4.2 Data Collection Procedure and Strategy

The importance of using appropriate techniques for study of thermal comfort of indoor occupants in dwellings is to gather data that is more consistent under the environment that enables the occupants to carry out their daily routines undisturbed during the period of surveys (Limbachiya et al., 2012). This study developed a plan to gather data required for analysis which had also been considered in past comfort field studies in dwellings (Ealiwa, et al., 2001; Limbachiya et al., 2012). The procedures include:

(a) All prefabricated modern timber houses in the UK built within the last ten years with good potential for research (built with prefabricated timber) and located in the most warming climatic regions (South and South-east of England) were identified. The developments were recipients of different sustainability or low-energy rating awards from reputable organisations.

(b) The buildings identified were studied to gather basic information and

understand their immediate environments.

(c) Housing developers and architects were contacted to seek their support and get relevant data required which helped this study to decide on the three case studies investigated.

(d) Development of the questionnaires for review and testing before approval for distribution.

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(e) Access to the case studies with permission granted by the various

organisations in charge of the buildings was secured. For example, the London Borough of Hackney was contacted for Bridport House and access was granted after careful consideration of the application.

(f) Submission of full ethics application for the research with human participants to the University of Kent Research Ethics Advisory Committee. The application was granted by the Committee through the Faculty of Humanities Research Ethics

Advisory Committee in order to seek the participants’ consent using the consent

form in line with the University’s Code of Ethical Practice for Research.

(g) Letters of introduction were sent to all residents of the buildings selected, highlighting the importance of the research, seeking their support and permission to be surveyed as well as enlighten them about the post-occupancy survey and what they were expected to do. The residents’ consent was collected using the consent form to express their willingness in participating in the survey and assuring them of confidentiality of the information that would be provided which would be treated anonymously. The occupants were also informed when and how the questionnaires would be administered and collected.

(h) Administration of paper-based post-occupancy questionnaires to all the

residents to gather data on how the internal environment is perceived and rated. (i) The occupants who were willing to participate in comfort surveys were contacted and houses to be monitored at the two case studies (Bridport and Oxley Woods) out of the three case studies considered for the post-occupancy surveys were also selected as access could not be secured at Stadthaus to carry out the indoor monitoring survey.

(j) Indoor measurements of environmental variables (air temperature and relative humidity) using HOBO and Tinytag data loggers that were marked using a code assigned to each space to be monitored and installed at a certain height above floor level were carried out concurrently with the administration of subjective

questionnaires to the participants. The accelerators to record windows’ open and

closed sessions were also installed in three houses at Oxley Woods.

(k) The returned questionnaires were collated and marked using codes for easy identification during analysis. The data loggers and subjective questionnaires were also retrieved.

54 (l) Analysis of the data collected using different statistical packages (SPSS- Statistical Package for Social Sciences) to determine variance and relationship between different variables and Excel to draw relevant charts.

(m) Relevant architectural drawings including construction details and specification documents collected from the developers and architects were further examined in order to draw plans using Computer Aided Design (CAD) package in preparation for dynamic thermal modelling and simulation. Thermal properties of

the case studies’ envelopes were also collected and other relevant information

required for modelling.

(n)The case study buildings were modelled using DesignBuilder (EnergyPlus) and

simulated under the same external conditions as the indoor measurements could only consider data for few days during the monitoring period.

The research procedure and strategy enhanced the quality of data gathered and thus improved the reliability of the results which will be discussed in Chapters 6 and 7. The next section describes each method considered in this study to collect data for analysis.