The contribution to UK climate mitigation targets from reducing embodied carbon in the construction sector

The UK construction industry faces the daunting task of expanding output whilst achieving substantial greenhouse gas emission reductions. Recent building life cycle assessments show that embodied carbon constitutes a growing proportion of whole life emissions. However, the precise distribution of embodied carbon along sector supply chains; the range of mitigation options available to practitioners and the potential policy responses have received little attention. This thesis addresses a number of these outstanding issues. The thesis commences with an analysis of the distribution of emissions along construction sector supply chains using Multi-Region Input Output modelling. The results of this analysis are combined with a large database of building carbon assessments to form a hybrid UK Buildings and Infrastructure Embodied Carbon model. This novel combination of bottom up project data and top down sector data provides a much needed link between sector carbon mitigation targets and project carbon intensity targets. A scenario analysis using the model suggests that, if external factors progress within the range of Government projections, current practices will be insufficient to meet sector targets. Therefore additional embodied carbon mitigation strategies must be implemented. One such mitigation strategy is increasing the use of alternative building materials with lower embodied carbon. This thesis presents a comprehensive overview of the barriers to uptake, based upon a literature review, survey of construction professionals and interviews with industry leaders. This research highlights the current lack of drivers for embodied carbon assessment and mitigation. In response, the thesis presents possible policy responses and industry led actions as a series of dynamic adaptive policy pathways developed through a participatory approach with key stakeholders. Collectively this thesis depicts the sizeable contribution embodied carbon abatement could make to the achievement of long-term UK climate mitigation targets and the interim response required from industry practitioners, institutions and policy makers

Methodology for the assessment of PV capacity over a city region using low-resolution LiDAR data and application to the City of Leeds (UK)

An assessment of roof-mounted PV capacity over a local region can be accurately calculated by established roof segmentation algorithms using high-resolution light detection and ranging (LiDAR) datasets. However, over larger city regions often only low-resolution LiDAR data is available where such algorithms prove unreliable for small rooftops. A methodology optimised for low-resolution LiDAR datasets is presented, where small and large buildings are considered separately. The roof segmentation algorithm for small buildings, which are typically residential properties, assigns a roof profile to each building from a catalogue of common profiles after identifying LiDAR points within the building footprint. Large buildings, such as warehouses, offer a more diverse range of roof profiles but geometric features are generally large, so a direct approach is taken to segmentation where each LiDAR point within the building footprint contributes a separate roof segment. The methodology is demonstrated by application to the city region of Leeds, UK. Validation by comparison to aerial photography indicates that the assignment of an appropriate roof profile to a small building is correct in 81% of cases

Solar city indicator: a methodology to predict city level PV installed capacity by combining physical capacity and socio-economic factors

Shifting to renewable sources of electricity is imperative in achieving global reductions in carbon emissions and ensuring future energy security. One technology, solar photovoltaics (PV), has begun to generate a noticeable contribution to the electricity mix in numerous countries. However, the upper limits of this contribution have not been explored in a way that combines both building-by-building solar resource appraisals with the city-scale socio-economic contexts that dictate PV uptake. This paper presents such a method, whereby a ‘Solar City Indicator’ is calculated and used to rank cities by their capacity to generate electricity from roof-mounted PV. Seven major UK cities were chosen for analysis based on available data; Dundee, Derby, Edinburgh, Glasgow, Leicester, Nottingham and Sheffield. The physical capacity of each city was established using a GIS-based methodology, exploiting digital surface models and LiDAR data, with distinct methodologies for large and small properties. Socio-economic factors (income, education, environmental consciousness, building stock and ownership) were chosen based on existing literature and correlation with current levels of PV installations. These factors were enumerated using data that was readily available across each city. Results show that Derby has the greatest potential of all the cities analysed, as it offers both good physical and socio-economic potential. In terms of physical capacity it was seen that over a 15 year payback period there are two plateaus, showing a marked difference in viability between small and large PV arrays. It was found that both the physical and socio-economic potential of a city are strongly influenced by the nature of the local building stock. This study also identifies areas where policy needs to be focused in order to encourage uptake and highlights factors limiting maximum PV uptake. While this methodology has been demonstrated using UK cities, it is equally applicable to any country where city data is available