This thesis investigates the role of co-design in the design and development of services that help householders to make decisions to make their homes more energy efficient by installing energy saving measures. The key issues facing co-design research are (1) the lack of understanding of how to increase and assess its impact and effectiveness, and (2) the provision of empirical evidence of the benefits associated with it. This thesis identifies and reviews different theoretical approaches to help provide evidence of the benefits associated with co-design (Chapter 2), adopting, applying and testing them throughout the empirical work. Research methods are also discussed alongside the particular challenges facing co-design research (Chapter 3). An exploratory study involving co-design practitioners (Chapter 4) confirmed what was shown to be lacking in the co-design literature, concluding with a need to focus on assessing the impact and effectiveness of co-design processes both theoretically and practically. A mixed methods study follows (Chapter 5) that took a service design perspective to identify how co-design could be applied to the design of energy advice and information, to explore householders individual decisions in detail, and to engage with householders to aid their understanding of the complex and intangible topic of energy . Chapters 6 and 7 then describe how co-design was applied to energy-related retrofit: firstly assessing the impact of co-design on householder s quality judgements of personalised information-based energy advice reports (i.e. the resulting designs from the co-design process), and secondly focusing on impact of the process aspect of co-design (i.e. what goes on ) on householders energy-related retrofit intentions, decisions and behaviours (i.e. the outcomes). Evidence of the benefits associated with co-design is provided including impact on the quality of resulting designs, and the role of co-design in enabling detailed understanding of peoples lived experiences and circumstances. The limitations of the particular analysis approach taken are then reported. The final study (Chapter 8) co-designs future energy-related service propositions with householders, building and energy technologists and user centred designers, highlighting the potential roles for smart energy data . The study concludes that immersing future end users into complex problem spaces is useful for co-designing future service propositions, and that it is beneficial to introduce wider stakeholders to develop concepts further. In understanding the outcomes of these studies, this thesis discusses (Chapter 9) the application of co-design to the energy-related retrofit domain, focusing in particular on (1) the implications of the approach taken to assessing the impact and effectiveness of co-design processes, (2) the benefits and drawbacks of incorporating personalised energy information in co-design activities, and (3) the limitations of integrating measures of impact and effectiveness into collaborative activities. Recommendations for the effective application of co-design are also presented. In conclusion, specific contributions and avenues for further work are highlighted (Chapter 10).

Urban environments are typically host to a high level of biodiversity which is important for the provision of ecosystem services, and for facilitating contact between humans and nature. However, accelerating urbanisation precipitates considerable declines in the number of species which inhabit these environments as a greater number of homes and roads are constructed to accommodate a growing global human population. Domestic gardens afford an important opportunity to combat these declines, owing to their capacity to support a high level of biodiversity and the substantial land area which they cover. However, the fine spatial scale of individual isolated domestic gardens constrains their ability to increase biodiversity at larger spatial scales. Consequently, managing domestic gardens collectively, by conjoining multiple neighbouring domestic gardens and managing them as a single larger habitat, has been proposed as a promising approach to increase biodiversity at these scales. Importantly however, the practical implementation of this approach necessitates neighbouring householders to collaboratively undertake biodiversity favourable garden management and to conjoin their domestic gardens. Crucially, this management is performed by householders discretionarily and can be influenced by demographic, perceptual, environmental, and socio-economic factors. Furthermore, householder attitudes towards conjoining domestic gardens may also influence the practicality of this approach. Therefore, this research explores what impact the extent to which householders undertake biodiversity favourable garden management has on the practicality of the collective management approach and how this is influenced by the aforementioned factors. In addition, it explores how this practicality is influenced by householder attitudes to conjoining domestic gardens. Lastly, it investigates how the collaborative undertaking of biodiversity favourable garden management by neighbouring householders could be encouraged, taking into consideration the constraints associated with current projects which promote such management. A survey was used to explore the prevalence of biodiversity favourable garden management, the influences on this management, and attitudes towards conjoining domestic gardens. This was conducted with an online semi-structured questionnaire which was distributed to householders using the social-networking site, Facebook. In addition, a bio-indicator approach was used to analyse the impact of general domestic garden management on biodiversity and birds were selected as a bio-indicator. Accordingly, respondents to the survey were also required to identify which bird species visit their domestic gardens. Seventeen elite interviews were also conducted with representatives from a range of organisations operating domestic garden projects, participants in such projects, and academics with expertise in domestic garden management, in order to explore the constraints associated with current domestic garden projects. The survey yielded 276 responses and provided support to the practicality of the collective management approach. In particular, it indicated that householders commonly undertake biodiversity favourable garden management, by predominantly providing food for birds and planting vegetation, and 60% of householders are willing to conjoin domestic gardens. However, the survey also highlighted that biodiversity favourable garden management is impeded by a number of factors. These included small domestic gardens, which particularly limit vegetation planting, and can be commonplace in urban environments. In addition, householders commonly nullify the benefits afforded by undertaking this management by covering domestic gardens with hard surface and lawns, which eliminate space for vegetation. Moreover, strong desires to retain ownership and privacy of domestic gardens precipitate the unwillingness of a significant proportion of householders to conjoin domestic gardens. This therefore challenges the practicality of the collective management approach. The results from the elite interviews indicated that householders lack commitment to current domestic garden projects, which are constrained by difficulties acquiring sufficient funding. These issues could also be pertinent to approaches which are developed to encourage the collaborative undertaking of biodiversity favourable garden management, further rendering the collective management approach impractical. The practicality of the collective management approach could be enhanced by modifying the design of new housing in a manner which is favourable to biodiversity and which ensures a minimal domestic garden size. In addition, including domestic gardens in green infrastructure strategies could further enhance this practicality. Furthermore, amending planning policy to regulate the covering of domestic gardens with hard surface and lawns more stringently could reduce the prevalence of these features. Householder commitment to approaches which encourage the collaborative undertaking of biodiversity favourable garden management could be promoted by providing feedback regarding the contribution this makes to increasing biodiversity at large spatial scales. Moreover, greater funding for these approaches could be acquired by also focusing on promoting the provision of ecosystem services. Finally, householder collaboration could be encouraged by accommodating desires for ownership and privatisation of domestic gardens. This could be respectively achieved by permitting flexibility regarding the biodiversity favourable garden management undertaken and separating conjoined domestic gardens with hedgerows.