Urban energy generation: The added value of photovoltaics in social housing

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Abstract

Social housing offers an alternative for low-to-medium income families and keyworkers (teachers, nurses, and police). In the United Kingdom (UK), this fairly priced, rental accommodation is normally owned by housing associations. This paper explores urban energy generation (micro-generation) focussing on photovoltaics (PV) and how its generated electricity can be used to provide added value in terms of demand reduction and contribute to a reduction in fuel poverty. It presents the results associated from in-depth monitoring of nine low-energy social housing units equipped with PV systems commissioned in 2004 in the South of England, UK. We report on energy load profiles and relate these to occupier behaviour and any changes in consumption that occur. The results highlight the impact of micro-generation showing a close correlation between occupant behaviour and energy consumption. Increased energy awareness can lead to changes in the way energy is used, reducing overall consumption but ‘education’ must be sustained to ensure long-term energy reductions. The financial benefit of operating high demand electrical appliances at the peak of the solar day as opposed to in the evening when overall demand on the central grid is higher is highlighted. The paper also draws conclusions allied to the challenges that PV micro-generation technology presents in the social housing context.

Introduction

Urban energy generation at the small scale can be defined as micro-generation and is simply the generation of energy—heat or electricity—by individual buildings or small groups of buildings. The technology that provides this energy distinguishes itself from that traditionally used in that it gives occupiers the responsibility to produce energy to partly sustain their homes or buildings. Micro-generation technologies include photovoltaic (PV) installations, micro-combined heat and power systems, micro-wind, solar thermal systems, fuel cells and micro-hydro systems. There is a huge potential to utilise this type of technology in the urban built environment not only to satisfy demand and provide decentralised generation but also to help tackle fuel poverty and achieve reduction in emissions.

In the United Kingdom (UK), the Government has set short term targets of reducing the country's carbon dioxide emissions to 20% below 1990 levels by 2010, to achieve 10% of electricity generation from renewable sources and to install 10 GW of combined heat and power capacity by the same year. In response to these targets and the provisions in the Energy White Paper (and subsequently, the UK Energy Act 2004), there have been two primary initiatives aimed at encouraging the installation of microgeneration technology—Clear Skies2 (solar thermal), and the Major Photovoltaic Demonstration Programme with total funding over 4 years of around £42.5 m [1]. In essence, the emphasis of these programmes is that if buildings can be made energy efficient and produce their own energy this will not only have a real impact on overall energy demand but also in tackling climate change.

In addition to the known environmental benefits, the impact of urban renewable energy generation on the occupier of a building can provide another impetus to justify its use and added costs. If one considers PV, as an example, there are now many exemplar buildings in which this technology fulfils the role of multifunctional building component [2], [3], [4]. Specifically, the use of PV laminates to provide weather protection, solar gain/solar shading control and also generating electricity. This is a testament to the flexibility of PV as a micro-generation technology in the built environment.

PV technology can also be considered in terms of both its direct and indirect energy benefits [5]. The direct benefit is clearly one of sustainable electrical power generation and also in financial savings. Indirect benefits are more subtle and span ‘softer’ issues such as pride in housing and increased energy awareness to technical issues such as generation at point of use, grid strengthening and, as will be highlighted here, the potential for demand reduction. It can also be argued that the use of PV when combined with occupier perception and behaviour can result in further environmental benefits or additionality that has not been previously reported. The linkage of occupier perceptions, energy generation and utilisation through surveys and system monitoring, as will be discussed in this paper, can highlight social, environmental and economic benefits aspects that are worthy of consideration when studying energy in buildings—especially in social housing.

Section snippets

Social housing

The cost of housing in the UK is extremely high. This applies equally to both rented accommodation and homes for ownership. This cost creates major problems as many critical public sector staff such as teachers; nurses and police are not able to afford housing close to their place of work. In addition, a significant proportion of the population either on low salaries or on social benefits cannot compete or afford such expensive housing. As an example, the average price of a house in the South

Urban energy generation (micro-generation)

Micro-generation—small scale electrical power generation at point of use—is seen to offer a range of potential benefits to both the homeowner and the network operator. Small scale PV such as that used in buildings (BiPV) can be termed as a micro-generation technology. It can be combined with other electrical power generating technologies such as wind (micro-wind) and micro combine heat and power (micro CHP) to arrive at what can be termed as urban energy generation technologies. Micro CHP is

Tariffs and subsidies

In terms of economics, energy efficiency and sustainability of domestic microgeneration technologies in the UK, it is generally very important to avoid export of generated electricity (or heat) [5]. In general, the tariff that a homeowner is paid for export of electricity to the grid is a fraction of the import cost. Typically, in the UK for example, a homeowner would be offered payment at ∼£0.02/kWh for electricity export, compared to being charged ∼£0.07/kWh for import. This poor tariff may

Electricity generation and demand

In the future, the advent of variable domestic electricity price tariffs (price rises and falls with demand during the day, following the centralised generation tariff) will increase the benefit of avoided export and enhance the use of more pro-active energy management schemes within buildings or houses.

As can be seen from Eq. (1), the advantage of a generation tariff rather than an export one is that there is a financial benefit to the homeowner in trying to avoid export of electricity from

Energy analysis in a social housing scheme

The thrust of this work is based on a recent social housing development located on the western side of Leigh Park in Havant, Hampshire. Leigh Park, built in the 1950s, was, at the time, Europe's largest social housing overseen by a local authority, but with the ‘right to buy’ many of the properties are now privately owned. The site is bounded by a school to the north, residential properties to the west and south and industrial units to the east. Before being developed this site was a car park

Added value of PV in social housing

The PV generation, import, export and consumption profiles for house H4 over a 24 h period (07/08/2004) is shown in Fig. 8. Over 70% of the PV generated electricity is exported from the house during this day. This is despite the fact that, over the entire day, the overall demand is 69% higher than the 8.2 kWh (integrated area under the bell curve) of electricity generated by the PV system. If the base load demand is accounted for it is clear that there are virtually no ‘active loads’ between

Conclusions

The use of building integrated photovoltaics in social housing developments in the UK can provide a significant contribution towards the annual electrical demand and an overall reduction of the fuel burden. Active load matching can enhance the financial return to the homeowner but current tariff schemes penalise energy efficient users in comparison to their high-demand neighbours. It has been shown that for very peaky profile users, with prolonged periods of high electricity consumption in both

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      Studies on the uptake of solar PV in other residential markets focus on specific challenges in social housing, private rental housing, and collective housing. In social housing markets, scholarly attention has been given to the role of tenant awareness and attitudes, of economies of scale in procurement, to operations and the flexibility to provide ancillary services, and to means to reduce the social and financial costs of energy to tenants (Agbonaye et al., 2020; Bahaj and James, 2007; Lee and Shepley, 2020; McCabe et al., 2018). Concerning private rental markets, research on PV adoption concerns its effect on rental prices and the need to change tenancy laws to facilitate greater solar uptake on rental properties (Best et al., 2021b, 2021a; Chegut et al., 2020; Nelson et al., 2019).

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