Yue Wu

Dust accumulation on solar photovoltaic (PV) modules reduces light transmission from the outer surfaces to the solar cells reducing photon absorption and thus contributing to performance reduction of PV systems. In regions such as the Middle East where dust is prevalent and rainfall is scarce, remedial measures are needed to reduce such impacts. Currently, various techniques are being employed to address such sand soiling ranging from mechanical (brushing) to active and passive electrical interventions. This research focuses on mechanical approaches encompassing module vibration, air and water jets, and combinations of these. A reconfigurable pilot-scale testbed of 8 kWp PV plant was installed on a carport shading system within the campus of King Abdulaziz University (KAU), Jeddah, Saudi Arabia. The functional PV carport was configured to allow water recovery and re-use within the testbed. Here, we discuss the overall cleaning design philosophy and approach, systems design, and how multiple cleaning configurations can be realised within the overall PV carport. Results indicate that in this location, sand soiling has a significant effect on performance of PV modules on a timescale of days. In addition, water jets optimised for high volume and low pressure were effective at reducing sand soiling with array power output increasing by over 27%, whilst air jets and module vibration were less effective in reducing soiling to an acceptable level. Overall, the testbed has provided a new approach to testing a combination of cleaning solutions in the field coupled with used water recovery. The proposed approach is important, as currently, there are a large number of solar PV projects being built in Saudi Arabia with more being planned for the future.

The research presented in this paper addresses a current gap in the availability of building geometry data and provides estimates of individual building characteristics at city scale. Such data are crucial for a wide range of subjects such as modelling building energy consumption as well as regional housing market studies. However, such data are currently not available in the UK. In this work, a new approach was developed to automatically estimate the geometric characteristics of buildings, including height and floor count. A wide range of datasets have been brought together including high-resolution light detection and ranging data to accurately estimate building elevation and to obtain the external dimension of buildings. In the UK, most of the datasets required for this model are available for urban areas, allowing the model to be widely applied both in cities and beyond. The paper presents the results of building height and floor count determined from this model and compares these with the actual data obtained from a survey of 108 representative buildings in the city of Southampton. The results show good accuracy of the model with 97% of the estimates having an error under ±1 floor and an absolute mean error of 0.3 floors. These results provide confidence in utilising this model for future building studies at a city scale.

The Energy Performance Certificate (EPC) requirements in Europe have provided rich data of energy efficiency status of individual buildings at scale, allowing appropriate assessments to be carried out without the need of conducting additional surveys. By 2012, the EPC data in England and Wales in the UK has reached a coverage of up to 45% of the entire building stock (DECC 2014), and the number of new certificates added every year is over 1 million. The work presented here seeks to understand the potential of using such dataset to deliver systematic analysis of energy efficiency of buildings at a city scale. This study utilizes all EPC datasets available for the city of Southampton, UK, and developed an automatic geographic-referencing methodology so the EPC data can be integrated onto geographic information systems (GIS). Such methodology allows large quantity of EPC data to be analyzed spatially, facilitating the assessment of energy performance of different regions in a city. The results show clearly areas in the city that have the lowest or highest level of performance in terms of buildings’ energy efffciency, and revealed the impact of certain building intervention measures (such insulation, double glazing) on the energy consumption within the considered buildings. The analyses show that factors such as the existence of high streets and new building developments have significant influence on the energy efficiency in the city where these are present. The geographic-referencing methodology developed in this study has the potential to be utilized in a wide range of subjects, bridging the current gap of data availability, allowing building related datasets to be incorporated with GIS analysis.

Reliance on fossil fuel-driven energy supply is a major contributor to global emissions. In order to stay within the Paris Agreement’s temperature rise limits, current and growing energy consumption will need to be significantly underpinned by deployment of low/non-carbon power generation. This work promotes power generation at the megawatt scale from solar photovoltaics (PV) systems deployed in untapped car parking areas, which are estimated to represent up to ~6.6% of the urban footprint within cities. The methodology developed is globally applicable to support PV development, including site selection and PV array configuration. It is underpinned by a case study in a university campus, which has a similar footprint as assigned in cities for vehicle parking. The methodology demonstrates that less than 1% of the available parking spaces are affected by shadows from surrounding buildings or vegetation. The work shows that by utilising such parking areas within the selected campus a PV installation with a capacity of ~36.4 MWp, which can generate ~66.2 GWh of electricity annually, would be feasible. Financial analysis based on multiple scenarios indicates that a 50% return on investment is achievable over 25 years at an export tariff of USD ¢4.5/kWh, which is commensurate with the latest granted bids for a similar export tariff.

Recently, much of the literature on sharing in cities has focused on the sharing economy, in which people use online platforms to share underutilized assets in the marketplace. This view of sharing is too narrow for cities, as it neglects the myriad of ways, reasons, and scales in which citizens share in urban environments. Research presented here by the Liveable Cities team in the form of participant workshops in Lancaster and Birmingham, UK, suggests that a broader approach to understanding sharing in cities is essential. The research also highlighted tools and methods that may be used to help to identify sharing in communities. The paper ends with advice to city stakeholders, such as policymakers, urban planners, and urban designers, who are considering how to enhance sustainability in cities through sharing.