An evaluation of the viability of photovoltaics in residential schemes managed by UK registered social landlords

Global demands on fossil fuels require the investigation of renewable and viable alternative energy supplies. The Intergovernmental Panel on Climate Change (IPCC) has concluded that current consumption of fossil fuels is untenable as atmospheric emissions of gases, in particular carbon dioxide (CO²), is having a significant and worsening effect on global climate change (IPCC 1992).

25% of UK CO² emissions are generated in the housing sector (UKCCP 2000). As major providers of UK social housing, Registered Social Landlords (RSLs), indirectly make a significant contribution to UK CO² emissions. In delivering UK Government policies, RSLs are required to meet national social and economic targets, as well as environmental targets. Clearly, social, environmental and economic issues combine in the arena of energy efficiency and social housing.

Potentially, the use of photovoltaics (PV) in social housing could assist the UK government in meeting targets in terms of affordable housing, providing "free" electricity to low income tenants, and with minimal environmental impact in urban areas. However, uptake of PV amongst RSLs in the UK has been minimal to date. This paper explores the factors that act as barriers to energy efficiency in this market.

Life-cycle energy analysis of building integrated photovoltaic systems (BiPVs) with heat recovery unit

Building integrated photovoltaic (BiPV) systems generate electricity, but also heat, which is typically wasted and also reduces the efficiency of generation. A heat recovery unit can be combined with a BiPV system to take advantage of this waste heat, thus providing cogeneration. Two different photovoltaic (PV) cell types were combined with a heat recovery unit and analysed in terms of their life-cycle energy consumption to determine the energy payback period. A net energy analysis of these PV systems has previously been performed, but recent improvements in the data used for this study allow for a more comprehensive assessment of the combined energy used throughout the entire life-cycle of these systems to be performed. Energy payback periods between 4 and 16.5 years were found, depending on the BiPV system. The energy embodied in PV systems is significant, emphasised here due to the innovative use of national average input–output (I–O) data to fill gaps in traditional life-cycle inventories, i.e. hybrid analysis. These findings provide an insight into the net energy savings that are possible with a well-designed and managed BiPV system.

Performance of building integrated solar hot water systems

The integration of solar energy systems into buildings has been the subject of considerable commercial and academic research, particularly building integrated photovoltaics. However, the integration of solar hot water systems into roofing systems has had far less attention. This paper presents the theoretical and experimental results of a novel building integrated solar hot water system developed using existing long run roofing materials.

This work shows that it is possible to achieve effective integration that maintains the aesthetics of the building and also provides useful thermal energy. The results of an unglazed 108m2 swimming pool heater and 8m2 glazed domestic hot water systems are presented.

The experimental results show that the glazed system performs close to the theoretical model and is an effective provider of hot water in certain climates. However it was also found that for larger scale building integrated solar water heating systems, special attention must be paid to the configuration and arrangement of the collectors in order to minimise problems with respect to flow distribution and its effect on collector and system efficiency.

Computational chemistry for graphene-based energy applications: progress and challenges.

Research in graphene-based energy materials is a rapidly growing area. Many graphene-based energy applications involve interfacial processes. To enable advances in the design of these energy materials, such that their operation, economy, efficiency and durability is at least comparable with fossil-fuel based alternatives, connections between the molecular-scale structure and function of these interfaces are needed. While it is experimentally challenging to resolve this interfacial structure, molecular simulation and computational chemistry can help bridge these gaps. In this Review, we summarise recent progress in the application of computational chemistry to graphene-based materials for fuel cells, batteries, photovoltaics and supercapacitors. We also outline both the bright prospects and emerging challenges these techniques face for application to graphene-based energy materials in future.

A pixel-based approach to estimation of solar energy potential on building roofs

Precise estimation of solar energy on building roofs plays a critical role in sustainable development and renewable energy consumption of high-density human habitats. Conventional solar radiation models based on costly Light Detection and Ranging (LiDAR) data are only adequate for existing buildings, not for future construction areas. In this paper, a pixel-based methodology is constructed for estimating solar energy potential over roofs. Buildings with flat roofs in a newly planned construction area are chosen as a case study. The solar radiation at a certain cell is mathematically formulated in the pixel unit, and its yields over a certain time period are calculated by considering multiple instantaneous solar irradiances and are visually presented by image processing. Significant spatial and temporal variations in solar radiation are measured. Within the study area, the maximum and minimum annual radiation yields are estimated at 4717.72 MJ/m2/year and 342.58 MJ/m2/year respectively. Radiation contour lines are then mapped for outlining installation ranges of various solar devices. For each apartment building, around 20% of roof areas can obtain 4500 MJ/m2/year or more solar radiation yields. This study will benefit energy investors and urban planners in accurately predicting solar radiation potential and identifying regions with high radiation over building roofs. The results can be utilised in government policies and urban planning to raise awareness of the use of renewable energy sources.