Imperial College London


Faculty of Natural SciencesCentre for Environmental Policy

Research Associate



+44 (0)20 7594 9248r.hanna




16 Prince's GardensSouth Kensington Campus





Publication Type

23 results found

Hanna R, Heptonstall P, Gross R, 2022, Green job creation, quality and skills: A review of the evidence on low carbon energy. UKERC Technology and Policy Assessment., Publisher: UK Energy Research Centre

The net employment impacts of a renewable energy or energy efficiency investment account both for jobs that are created, as well as jobs that might be displaced in other parts of the economy as a result of the investment. This report therefore addresses the following research question:How many jobs can be created by policy support for investment in low carbon energy and energy efficiency compared to supporting fossil fuel incumbents?The review identifies a variety of approaches used to estimate the quantity of low carbon energy job creation. It finds that much greater standardisation of methods would be desirable in order to compare how many jobs can be created by policies supporting low carbon energy and energy efficiency, both at a project scale and a wider societal level. Our findings also underline a relative lack of metrics and data measuring quality, skills, and geographic distribution of low carbon job creation, and these should be priority areas for further research.


Trask A, Hanna R, Rhodes A, 2022, The future of home heating: The roles of heat pumps and hydrogen, The Future of Home Heating: The Roles of Heat Pumps and Hydrogen

In this Briefing Paper, the prospectsfor the future of home heating areanalysed with specific reference toheat pumps and hydrogen heating.The report is based on extensiveliterature surrounding the topic ofdecarbonisation of the heat sectorin the UK and will discuss thevarious advantages, challenges, andtechnicalities surrounding the twotechnologies. The evidence gatheredand discussed culminates in a set ofrecommendations that prioritise keyareas that require addressing overthe course of the next decade.


Hanna R, Gross R, 2021, Heating system transformation in Europe: accelerating sources of path dependence to escape carbon lock-in, Research Handbook on Energy and Society, Publisher: Edward Elgar Publishing, ISBN: 9781839100703

In this chapter, we present evidence from a systematic review on how policies, markets and natural resource availability have affected heat system change and decarbonisation in Denmark, Germany, and the United Kingdom. We focus on two heat supply technologies for which sufficient historic evidence of policies and market evolution is available: heat pumps and district heating. Our review reveals that initially unfamiliar, low carbon heating technologies can become mainstream over several decades. A key challenge of heat decarbonisation is transitioning from relatively low-cost heating sources that are either inherited from a country’s natural resources or originate from path-dependent developments. This may involve accepting initially higher costs, developing new infrastructure, and co-ordinated consumer awareness campaigns to promote low carbon heating alternatives. To overcome lock-in to high carbon heating, policy makers should aim to stimulate increasing returns to adoption of alternative, low carbon heating solutions over a prolonged period of policy action.

Book chapter

Carmichael R, Gross R, Hanna R, Rhodes A, Green Tet al., 2021, The Demand Response Technology Cluster: accelerating UK residential consumer engagement with time-of-use tariffs, electric vehicles and smart meters via digital comparison tools, Renewable and Sustainable Energy Reviews, Vol: 139, ISSN: 1364-0321

Cost-effectively decarbonising the power sector and household energy use using variable renewable energy will require that electricity consumption becomes much more flexible and responsive to constraints in supply and the distribution network. In recent years residential demand response (DR) has received increasing attention that has sought to answer, based on current evidence, questions about how much consumers will engage with DR. This paper critically reviews the evidence base for residential consumer engagement with DR and draws out several important limitations in it. We argue for a more action- oriented focus on developing practical strategies to enable and unlock greater loadshifting and consumer engagement with DR within a changing technology and regulatory context. A number of recommendations are put forward for accelerating UK consumer engagement with DR, presented under three broad strategies: (a) promote awareness of smart tariffs, smart meters and storage and automation behind-the-meter devices as mutually-supportive components within a common ‘DR technology cluster’; (b) deliver targeted support for adoption of electric vehicles and other storage and automation technologies; (c) enable and support informed adoption of DR-enabling products and services through ‘smarter’ digital comparison tools (DCTs), data portability, and faster, simpler switching. The interdependency between components within this DR technology cluster delivers efficiency but also poses a risk that one delayed component (e.g., smart metering) will hold-up policy and industry support for other components. The urgency of decarbonisation goals makes it necessary to push forward as many of these elements as possible rather than the pace being set by the slowest.

Journal article

Hanna R, Gross R, 2021, How do energy systems model and scenario studies explicitly represent socio-economic, political and technological disruption and discontinuity? Implications for policy and practitioners, Energy Policy, Vol: 149, ISSN: 0301-4215

Scenarios may be qualitative or quantitative, the latter of which can be developed using energy systems models. This study explores how different energy systems models and scenarios explicitly represent and assess potential disruptions and discontinuities. The focus is on futures studies and forward-looking scenario and modelling exercises. We apply definitions of ‘emergent’ (uncoordinated) and ‘purposive’ (coordinated) disruption to a systematic review on how energy systems models and scenarios have been used to capture disruption and discontinuity. We first conducted a review of reviews of energy models and scenarios to provide an overview of their common classifications. Additional searches then sought studies which use different types of models and scenarios to explore disruption and discontinuity. We analyse a subset of 30 of these modelling or scenario studies in which authors self-identify and represent disruption or discontinuity, finding that the most frequently used methods were qualitative, exploratory foresight scenarios or agent-based models. We conclude that policy makers could prepare more effectively for social, economic and political disruption by integrating multidisciplinary insights from social and political sciences, engineering and economics through a broader range of methods: exploratory, foresight scenarios, simulation and agent-based models and repurposed energy systems optimisation models.

Journal article

Carmichael R, Rhodes A, Hanna R, Gross Ret al., 2020, Smart and flexible electric heat: an energy futures lab briefing paper, Smart and Flexible Electric Heat: An Energy Futures Lab Briefing Paper

Heating in residential, commercial and industrial settings makes up almost half of final energy consumption in the UK, more than the energy consumed for electricity or transport. The electrification of heat is anticipated to play a major role for the UK’s efforts to reduce emissions to net-zero by 2050. Heating demand is highly variable between seasons and time of day. To take maximum advantage of low-carbon generation, and to respect the limitations of the distribution grid, electricity loads for heating will need to be flexible. This Briefing Paper explores the potential for smart flexible low-carbon electric heating in UK homes and the challenges for consumer engagement. This paper considers four key elements for enabling smart, flexible and cost- effective electric heating in UK homes: low-carbon heating systems; cost-reflective electricity pricing; thermally efficient buildings; and smart storage devices.


Kozarcanin S, Hanna R, Staffell I, Gross R, Andresen GBet al., 2020, Impact of climate change on the cost-optimal mix of decentralised heat pump and gas boiler technologies in Europe, Energy Policy, Vol: 140, Pages: 1-13, ISSN: 0301-4215

Residential demands for space heating and hot water account for 31% of the total European energy demand. Space heating is highly dependent on ambient conditions and susceptible to climate change. We adopt a techno-economic standpoint and assess the impact of climate change on decentralised heating demand and the cost-optimal mix of heat pump and gas boiler technologies. Temperature data with high spatial resolution from nine climate models implementing three Representative Concentration Pathways from IPCC are used to estimate climate induced changes in the European demand side for heating. The demand side is modelled by the proxy of heating-degree days. The supply side is modelled by using a screening curve approach to the economics of heat generation. We find that space heating demand decreases by about 16%, 24% and 42% in low, intermediate and extreme global warming scenarios. When considering historic weather data, we find a heterogeneous mix of technologies are cost-optimal, depending on the heating load factor (number of full-load hours per year). Increasing ambient temperatures toward the end-century improve the economic performance of heat pumps in all concentration pathways. Cost optimal technologies broadly correspond to heat markets and policies in Europe, with some exceptions.

Journal article

Ketsopoulou I, Taylor P, Watson J, Winskel M, Kattirtzi M, Lowes R, Woodman B, Poulter H, Brand C, Killip G, Anable J, Owen A, Hanna R, Gross R, Lockwood Met al., 2019, Disrupting the UK energy system: causes, impacts and policy implications, London, UK., Publisher: UK Energy Research Centre


Gross R, Hanna R, 2019, Path dependency in provision of domestic heating, Nature Energy, Vol: 4, Pages: 358-364, ISSN: 2058-7546

In the UK, natural gas dominates the provision of heating in buildings. In Sweden, oil heating has been largely replaced by district heating and heat pumps. The origins and outcomes of path dependence and lock-in in heat system evolution can be country specific. Here, we compare case studies of heat transitions in the UK and Sweden, addressing the question: can path dependency help to understand why these countries have followed different paths in terms of change to their heating infrastructure? In both countries the development of heating infrastructures can be understood as path dependent processes, entailing increasing returns to adoption as fuel sources, infrastructures and end use technologies coevolve such that the overall performance of the system increases. The challenge for policymakers seeking to achieve carbon targets is to consider how to create the conditions to encourage increasing returns to adoption of low carbon heating solutions.

Journal article

Kazaglis A, Tam A, Eis J, Watson J, Hughes N, Gross R, Hanna Ret al., 2019, Accelerating innovation towards net zero emissions, Publisher: Vivid Economics


Gross R, Hanna RF, Gambhir A, Heptonstall P, Speirs Jet al., 2018, How long does innovation and commercialisation in the energy sectors take? Historical case studies of the timescale from invention to widespread commercialisation in energy supply and end use technology, Energy Policy, Vol: 123, Pages: 685-699, ISSN: 0301-4215

Recent climate change initiatives, such as ‘Mission Innovation’ launched alongside the Paris Agreement in 2015, urge redoubled research into innovative low carbon technologies. However, climate change is an urgent problem – emissions reductions must take place rapidly throughout the coming decades. This raises an important question: how long might it take for individual technologies to emerge from research, find market opportunities and make a tangible impact on emissions reductions? Here, we consider historical evidence for the time a range of energy supply and energy end-use technologies have taken to emerge from invention, diffuse into the market and reach widespread deployment. We find considerable variation, from 20 to almost 70 years. Our findings suggest that the time needed for new technologies to achieve widespread deployment should not be overlooked, and that innovation policy should focus on accelerating the deployment of existing technologies as well as research into new ones.

Journal article

Hanna RF, Gazis E, Edge J, Rhodes A, Gross Ret al., 2018, Unlocking the potential of Energy Systems Integration: An Energy Futures Lab Briefing Paper, Publisher: Energy Futures Lab

Energy Systems Integration’s (ESI) underlying concept is the coordination, and integration, of energy generation and use at local, regional and national levels. This relates to all aspects of energy from production and conversion to delivery and end use. Building such a system is potentially a cost-effective way to decarbonise our energy sector and produce a more reliable and resilient system. This Briefing Paper investigates how the UK can link heat, transport, electricity and other energy vectors into one interconnected ecosystem. It lays out the immense opportunities of having an interconnected and integrated energy ecosystem and the technologies that could make it a reality. Among these is enabling variable renewable electricity and lower-carbon fuels to provide energy services traditionally provided by higher-carbon sources. This could be realised through a more resilient system incorporating greater flexibility and more diverse energy sources.


Sahni A, Kazaglis A, Hanna RF, Gross R, Kemp L, Kingsmill N, McCormac Eet al., 2018, International comparisons of heating, cooling and heat decarbonisation policies, Publisher: Department for Business, Energy & Industrial Strategy

As part of its wider research into heat decarbonisation, BEIS commissioned Vivid Economics and Imperial College to summarise the evidence base on how other countries provide heating and cooling. The focus of this report is heating and cooling in buildings, viewed broadly across residential and non-residential sectors with an emphasis on OECD countries. The report focuses on two overarching questions:- what challenges are shared by the UK and with other countries in the area of heat decarbonisation and where is there less commonality?- what learning and innovation opportunities exist outside of the UK, both in countries where there are clear points of comparisons as well as contrasts?


Hanna RF, 2017, Community Renewables Innovation Lab: Energy Transition Platform policy briefing, Publisher: The Climate Group

Community renewables are installations of renewable electricity such as solar panels or wind turbines, which are owned by, or have significant benefits for, residents and local organisations. Such schemes not only help regional governments meet their carbon reduction targets, but they also engage citizens in the wider clean energy transition. Projects are considered as ‘community’ schemes if residents are highly involved in decision-making, or if there are local benefits such as energy access, job creation, regeneration and education. This policy briefing highlights the opportunities and challenges of developing community renewable schemes in four different states and regions in Canada, Spain, the UK and the US. The research is part of the Climate Group's Energy Transition Platform through which states and regions work together to overcome barriers to the adoption of low carbon energy policies and technologies. For schemes owned by community co-operatives, a significant challenge is raising sufficient capital. Without existing financial capacity in the local community, innovative approaches such as crowd funding are needed. While up-front and ongoing investment subsidies are beneficial, such financial support is often time limited and may not be sustainable long term. Hybrid models of ownership, such as partnerships between commercial developers, community organisations and local authorities, may be the most plausible arrangement. Capturing wider socio-economic benefits for local communities is also a challenge for commercially-led schemes, but may be more possible with hybrid ownership models. And while regional and national legislation can help – it can also hinder uptake of community renewables. One further challenge in three of the four states/regions considered is how to develop a smart grid infrastructure that can integrate large volumes of distributed generation.


Hanna RF, Leach M, Torriti J, 2017, Microgeneration: The installer perspective, Renewable Energy, Vol: 116, Pages: 458-469, ISSN: 1879-0682

This paper presents an exploratory analysis of microgeneration installer businesses in the UK during a period of intense change in policies supporting microgeneration from 2010 to 2012. The research examines the influence of installer businesses on rates of uptake and standards of installation, and the interplay between business practices and the policy environment. The research developed new detailed datasets through a nationwide survey, to which 388 installers responded, and follow-up interviews with 22 installers. Focusing on solar photovoltaics and air source heat pumps installed in households, the results show the fundamental dependence of installer businesses on government financial incentives and on the quality assurance scheme in operation. Market confidence was compromised by the sharp reduction in the Feed-In Tariff (FIT) for residential solar PV in 2012 and long delays to the equivalent Renewable Heat Incentive for residential installations. Nevertheless, more modest FIT levels have reduced the risk of sub-optimal installations and inappropriate specification of microgeneration systems. The findings underline the need for consistent policy to allow installer businesses and their supply chains to develop and mature, and thus facilitate commercial deployment of microgeneration of high quality, raise its competiveness with incumbent forms of energy supply and contribute to decarbonisation goals.

Journal article

Pothitou M, Hanna R, Chalvatzis K, 2017, ICT entertainment appliances' impact on domestic electricity consumption, Renewable and Sustainable Energy Reviews, Vol: 69, Pages: 843-853, ISSN: 1364-0321

Increased electricity consumption and environmental impacts of Information Communication Technology (ICT) have been subjects of research since the 1990s. This paper focuses on consumer electronics in households, in particular TVs, computers and their peripherals. ICT accounts for almost 15% of global domestic electricity use, including waste energy from devices left on standby which is estimated in the EU-27 to contribute 6% of residential energy demand. In Europe, the household electricity consumption from small electronic appliances, including ICT, increased by 2.5 times in 2011 compared to 1990. Similarly, in the UK, energy demand from electronic devices accounted for 23% of total household electricity use in 2012, compared to 12% in 1990. This is an outcome of the market saturation of new, cheaper ICT entertainment devices, facilitated by marketing strategies which identify new needs for consumers, as charted by the review of market growth in this paper. New increasingly portable laptops, smart phones and tablets with wireless connectivity allow householders to perform a wider range of activities in a wider range of locations throughout the home, such as social networking while the television is active. We suggest that policies which consider how to increase the energy efficiency of ICT devices alone are unlikely to be successful since effective strategies need to address how the drivers which have developed around the use of ICT can be adapted in order to conserve electricity in households. A range of policy solutions are discussed, including feedback, public information campaigns, environmental education, energy labelling, bans of, or taxation on the least efficient products as well as the use of a TV as central hub to perform the existing functions of multiple devices.

Journal article

Hanna RF, Gross R, Parrish B, 2016, Best practice in heat decarbonisation policy: A review of the international experience of policies to promote the uptake of low-carbon heat supply

This evidence review evaluates the effectiveness of different policy approaches to support heat supply or infrastructure transitions internationally. Focusing on heat pump deployment and the roll out of district heating, the research identifies lessons from the international policy experience and assess how relevant these might be to the UK context. The report explores the role of different policies – including regulation, fiscal policies, incentives, planning policy and of different models of governance. It also considers historical and contextual factors such as ownership structures, resource endowments and energy prices. The review was undertaken by the UKERC Technology and Policy Assessment team in response to widespread stakeholder interest in policies related to the decarbonisation of heat. It informs the Committee on Climate Change review of heat decarbonisation and seeks to inform the UK Government’s heat strategy, forthcoming in 2017. The main aim of the research is to review and evaluate policies and policy packages used to bring about a substantial change in the technologies and infrastructures used to provide space heating and hot water for homes and businesses. The key question that this TPA project therefore asked is: What policies and other factors have driven change/transformation in heat delivery technologies, fuels and infrastructure?


Pothitou M, Hanna R, Chalvatzis K, 2016, Environmental knowledge, pro-environmental behaviour and energy savings in households: An empirical study, Applied Energy, Vol: 184, Pages: 1217-1229, ISSN: 0306-2619

In this paper we evaluate the impact of knowledge about environmental and energy issues on potential pro-environmental behaviour in households, specifically relating to behaviours, attitudes and habits towards energy use. Our results are based on an empirical survey and we find significant correlations which indicate that residents with positive environmental values and greater environmental knowledge are more likely to demonstrate energy behaviours, attitudes and habits which lead to energy saving activities in households. This is further supported through a Principal Component Analysis (PCA), which suggests that energy saving behaviour may also vary according to gender and employment status. Conversely, we find only limited evidence of statistical associations between environmental predisposition and knowledge, and ownership and frequency of use of household appliances. We argue that our results contribute to the significant body of literature supporting the role of knowledge in active engagement with energy issues. This study is timely following closely policy developments in active consumer engagement by the European Commission.

Journal article

Hanna R, Gross R, Speirs J, Heptonstall PJ, Gambhir Aet al., 2015, Innovation timelines from invention to maturity: A rapid review of the evidence on the time taken for new technologies to reach widespread commercialisation


Torriti J, Hanna R, Anderson B, Yeboah G, Druckman Aet al., 2015, Peak residential electricity demand and social practices: Deriving flexibility and greenhouse gas intensities from time use and locational data, Indoor and Built Environment, Vol: 24, Pages: 891-912, ISSN: 1423-0070

Peak residential electricity demand takes place when people conduct simultaneous activities at specific times of the day. Social practices generate patterns of demand and can help understand why, where, with whom and when energy services are used at peak time. The aim of this work is to make use of recent UK time use and locational data to better understand: (i) how a set of component indices on synchronisation, variation, sharing and mobility indicate flexibility to shift demand; and (ii) the links between people's activities and peaks in greenhouse gases' intensities. The analysis is based on a recent UK time use dataset, providing 1-min interval data from GPS devices and 10-min data from diaries and questionnaires for 175 data days comprising 153 respondents. Findings show how greenhouse gases' intensities and flexibility to shift activities vary throughout the day. Morning peaks are characterised by high levels of synchronisation, shared activities and occupancy, with low variation of activities. Evening peaks feature low synchronisation, and high spatial mobility variation of activities. From a network operator perspective, the results indicate that periods with lower flexibility may be prone to more significant local network loads due to the synchronisation of electricity-demanding activities.

Journal article

Hawkes A, Hanna R, 2015, Market and policy influences, Domestic Microgeneration Renewable and Distributed Energy Technologies, Policies and Economics, Publisher: Routledge, ISBN: 9781317448853

Renewable and Distributed Energy Technologies, Policies and Economics Iain Staffell, Daniel J.L. Brett, Nigel P. Brandon, Adam D. Hawkes. [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] ...

Book chapter

Hanna RF, 2014, Installer businesses and renewable energy uptake in homes

Thesis dissertation

Hanna RF, Leach M, Torriti J, 2012, The impact of installer business models on the uptake of residential microgeneration in the UK: Evidence from a nation-wide survey, British Institute of Energy Economics conference: European energy in a challenging world - The impact of emerging markets

Conference paper

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: Request URI: /respub/WEB-INF/jsp/search-html.jsp Query String: respub-action=search.html&id=00874978&limit=30&person=true