How Demand Varies: Peaks, trends and rhythms

It is increasingly important to know about when energy is used in the home, at work and on the move. Aspects of time and timing have not featured strongly in energy policy analysis or in modelling but if smarter ways of balancing supply and demand are to take hold, and if decarbonised forms of supply are to be used effectively, it is essential to understand and intervene in patterns of societal synchronisation, and in the rhythms of demand.

This calls for detailed knowledge of when, and on what occasions many people engage in the same (energy demanding) activities at the same time, of how such patterns are changing, and of how they might be shaped. For example, the impact of smart meters and controls partly depends on whether there is, in fact scope for shifting the timing of what people do, and for changing the rhythm of the day. Everyday sequences and collective schedules limit flexibility at a societal scale and institutions and organisations have rhythms of their own: all matter for the timing of energy demand, and all do so in ways that cannot be adequately captured or addressed by conventional approaches which focus on individual behaviour and choice.

Temporal and Spatial Variation 

There is a clear need for more sophisticated analyses of spatial, temporal and social variations in end use practices in order to produce more refined scenarios of future demand, and to inform current policy initiatives and critically examine their effects. At a minimum, this depends on conceptualizing the spatial and temporal ‘profiles’ of energy demanding practices, and understanding how these evolve.

Some of our work applies social theories of time to questions of energy demand and looks at how ‘time’ features in studies of transport and energy.

  • Hui, A. (2017) Variation and the intersection of practices. In Hui, A. Schatzki, T. and Shove, E (eds.) The Nexus of Practices: Connections, constellations, practitioners. London: Routledge PDF.  This chapter develops a conceptual vocabulary for discussing how practices vary – differentiating types of variation within and between practices. It highlights that in addition to being a basic feature of practices, variation exists in relation to practices and their spatio-temporal intersections. Through a range of empirical examples, the chapter develops a language and set of analytic tools for articulating and investigating variation in practices..
  • Walker, G. (2014) The Dynamics of Energy Demand: Change, Rhythm and Synchronicity. Energy Research and Social Science, 1, 49-55. DOI: 10.1016/j.erss.2014.03.012 . This paper lays out the relevance of the investigation of the underlying social dynamics and temporalities of energy demand for energy and social science research. Three forms or categories of dynamic are discussed – change, rhythm and synchronicity – each providing a different way of approaching the relation between time, social practice and energy demand.
  • The timing of domestic energy demand – insights from the 1920s – 2000s, Research Insight 8, DEMAND Centre. The timing of energy demand is important for energy policy and reducing carbon emissions and domestic energy demand is influenced by more than just household energy infrastructures, routines and appliances. This research insight examines how changes to these and institutions beyond the home have impacted on patterns of occupancy and household energy demand.
  • Mattioli, G., Shove, E., and Torriti, J. (2014)  The timing and societal synchronisation of energy demand (PDF). DEMAND Working Paper 1. It is increasingly important to know about when energy is used in the home, at work and on the move. Issues of time and timing have not featured strongly in energy policy analysis and in modelling, much of which has focused on estimating and reducing total average annual demand per capita. If smarter ways of balancing supply and demand are to take hold, and if we are to make better use of decarbonised forms of supply, it is essential to understand and intervene in patterns of societal synchronisation
  • Anable, J., Anderson, B., Shove, E. and Torriti, J. (2014) Categories, Concepts and Units: Representing energy demand in and through time. DEMAND Working Paper 3. Methods of data collection are unavoidably rooted in some sort of theoretical paradigm, and are inextricably tied to an implicit agenda or broad problem framing. These prior orientations are not always explicit, but they matter for what data is collected and how it is used. This exercise reveals systematic differences of method and approach, for instance in units of measurement, in how issues of time/duration and periodicity are handled, and how these strategies relate to the questions such data is routinely used to address.
  • Anderson, B. (2016) Laundry, energy and time: Insights from 20 years of time-use diary data in the United Kingdom. Energy Research & Social Science. 22, 125-136. DOI: 10.1016/j.erss.2016.09.004. This paper uses current and historical time-use diary data to explore the temporal change in laundry practices in the United Kingdom over the last 20 years. ‘Doing the laundry’ is frequently cited as a potentially ‘flexible demand; and yet very little is known about when people do the laundry, who does it at particular times, how this has changed and what implications this might have for the flexibility of demand.
  • Hui, A. and Walker, G. (2016) Potential pathways, human activities and multiple time-spaces: expanding understandings of energy demand geographies (PDF), Paper prepared for DEMAND Centre Conference, Lancaster, 13-15 April 2016. The idea that human activities are best understood in relation to emerging and evolving pathways has become established within multiple strands of social scientific thought. Despite the dominance of mobility-related cases, for example in transportation research, there has been limited exploration of how these ideas might contribute to broader understandings of energy demand. This paper argues that further conceptualisation and investigation of pathways in relation to the temporal and spatial patterns of energy-demanding activities offers important contributions.

As well as developing new ways of thinking about energy demand in time and space, the DEMAND Centre seeks to provide a detailed analysis of the structure of contemporary energy consuming practices by time of day, day of week, time of year.

  • Torriti, J. (2014). A Review of Time Use Models of Residential Electricity Demand. Renewable and Sustainable Energy Reviews, 37, 265-272. DOI: 10.1016/j.rser.2014.05.034. The timing of residential electricity demand has significant impacts on carbon emissions and system costs. This paper reviews the data and methods used in time use studies in the context of residential electricity demand modelling. It highlights key issues which are likely to become more topical for research on the timing of electricity demand following the roll-out of smart meters.
  • López-Rodríguez, M. A., Santiago, I. Trillo-Montero, D., Torriti, J. and Moreno-Munoz, A.(2013). Analysis and Modelling of Active Occupancy of the Residential Sector in Spain: An Indicator of Residential Electricity Consumption. Energy Policy, 62, 742-751. DOI: 10.1016/j.enpol.2013.07.095. Demand Side Management solutions require detailed knowledge about the patterns of energy consumption. The profile of electricity demand in the residential sector is highly correlated with the time of active occupancy of the dwellings; therefore in this study the occupancy patterns in Spanish properties was determined using the 2009–2010 Time Use Survey (TUS), conducted by the National Statistical Institute of Spain.
  • Anderson, B.(2016)  DEMANDing times (PDF). Paper prepared for DEMAND Centre Conference, Lancaster, 13-15 April 2016. Given that only about 35% of the variation in domestic energy use can be attributed to physical building attributes, if we are to achieve the UK policy goal of reducing energy consumption by 20%, then it appears axiomatic that we need to understand the factors that drive the ‘missing’ 65%. This can only come from improving our understanding of what people actually do with energy, why they do it and how the current state of play came to be.
  • Fluctuations and rhythms of demand, sound bite by Jillian Anable, February 4, 2014. Jillian talks about how DEMAND’s approach to rhythms of demand may differ from other approaches.

Timing and location are closely related and both impact on the patterning of energy demand. Understanding where energy is used (at home, at work, on the train) depends on knowing about the spatial characteristics of end use practices.

Burkinshaw, J. (2016) Creative vs non-creative: The role of flexible working practices on travel demand. Paper prepared for the WCTRS conference.

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Time Pressures and Peak Demand

Knowing how end use practices vary, when and where they occur, and how and why they change over time is crucial if carbon reduction policies involving real time management or the decentralisation of supply are to have any chance of success.

Present and future strategies of demand management depend on detailed knowledge of when end-use practices happen, how they are sequenced and how flexible they are in terms of timing and duration. This is key for estimating and influencing the risks of peak demand, and for making widespread use of more intermittent forms of renewable energy.

We use novel activity sequencing approaches to produce innovative insights into the synchronity of practices within households, determining which are predictable and which are more variable; identifying the relation between peak demand in mobility and in energy used in buildings; specifying time pressures and hotspots of energy demand, and the temporal and spatial flexibility of routine and infrequent mobility practices. We seek answers to questions about which end uses are likely to change, how practices vary, and how this affects peak load.

  • What makes peak electricity demand? Insights from time use analysis (PDF), Research Insight 1, DEMAND Centre. Detailed monitoring of domestic electricity consumption is beginning to provide some insight into the types of demand that feature across different parts of the day. However such data is limited in scope and cannot provide a differentiated view of how electricity demand relates to patterns in what people are doing during peak periods and how this varies. An alternative approach is to use time use data.
  • Torriti, J. (2016). Peak Energy Demand and Demand Side Response, London: Routledge. This book presents evidence on a set of Demand Side Response activities, ranging from price-based to incentive-based programmes and policies. Examples are drawn from different programmes for both residential and non-residential sectors of electricity demand, including Time of Use tariffs, Critical Peak Pricing Automated Demand Controllers and Ancillary Services. The book also looks at the actual energy saving impacts of smart meters, the activities which constitute peak demand and the potential opportunities associated with European smart grids and Capacity Markets.
  • Torriti, J. and Grunewald, P. (2014). Demand Side Response: Patterns in Europe and Future Policy Perspectives under Capacity Mechanisms. Economics of Energy and Environment Policy, 3(1), 87-105. This paper aims to both examine the reasons for low levels of Demand Side Response (DSR) in Europe and reflect on factors that might affect the participation of DSR in capacity mechanisms. Findings show that changes to the duration of contracted loads under existing or new programmes might increase the penetration of DSR. The introduction of capacity mechanisms may increase DSR from demand turn down if longer response times were available.

Temporal flexibility and the capacity to shift activities to different times of day is a key concern.

  • Lightening the load: Changes in the timing of laundry (PDF), Research Insight 2, DEMAND Centre. There is considerable interest in understanding the activities that contribute to evening peak electricity demand, especially those that may be ‘shift-able’. Here we focus on laundry: washing and drying clothes. Doing the laundry is a routine yet significant component of energy demand, but is also an oft-quoted example of an activity which is, in principle, shiftable in its timing. But is a widespread shift in the timing of laundry really plausible?
  • Grunewald, P. (2016). Flexibility in supply and demand (PDF). Paper prepared for DEMAND Centre Conference, Lancaster, 13-15 April 2016. Flexibility in demand is emerging as an increasingly sought after property in electricity systems. This paper systematically reviews flexibility as a dynamic property on supply and demand side. In doing so it attempts to shift the perspective from ‘what flexibility is for’ to ‘where flexibility is coming from’. This approach leads to the conclusion that even seemingly automated forms of demand response rely, to a large degree, on the flexibility of energy users.
  • Torriti J. and McGraw, T. (2016). Time of the day dependence of social practices and energy demand (PDF) Paper prepared for DEMAND Centre Conference, Lancaster, 13-15 April 2016. This paper aims to assess how dependent energy-related social practices in the household are in relation to the time of the day. The focus is on social practices over temporal scales of different days of the week and months of the year.
  • Torriti, J., Druckman, A., Anderson, B., Yeboah, G. and Hanna, R. (2015). P eak Residential Electricity Demand and Social Practices: Deriving Flexibility and Greenhouse Gas Intensities from Time Use and Locational Data. Indoor and Built Environment, 24(7), 891-912. DOI: 10.1177/1420326X15600776. 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 how a set of component indices on synchronisation, variation, sharing and mobility indicate flexibility to shift demand, as well as the links between people’s activities and peaks in greenhouse gases’ intensities.

Peaks relating to eating are especially interesting.

  • Durand-Daubin, M. (2016) Cooking in the night: peak electricity demand and people’s activity in France and Great Britain (PDF). Paper prepared for DEMAND Centre Conference, Lancaster, 13-15 April 2016. This research looks for the energy footprint of practices which are widely shared, highly regular, and key markers in the social organisation: eating practices. We studied the regional timing of this social synchronisation, across several time scale and areas. This comparison reveals a significant link between the time of the evening electricity demand peak and the time and synchronisation of cooking
  • Morley, J. and Shove, E. (2015) Size is everything at Christmas and your oven is no exception, an article published in The Conversation, January 5, 2015. Ovens are designed and optimised for roasting large birds. As a result, they are typically oversized for regular use – making their total energy consumption greater than necessary. And it is not only ovens that are designed to cope with the special demands of the festive season. This article points to fundamental questions about the relation between technical provision, sizing for the peak, and actual patterns of consumption and demand.

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Institutional Rhythmns

It’s important to understand how institutions shape the timing of working and travel practices and how institutional rhythms might be modified in fostering lower carbon patterns of work and travel. Examples of institutional and commercial arrangements that structure social-temporal rhythms include opening hours, patterns of leisure and retail provision and the ‘standard’ office or school day.

  • Hui, A., Shove, E. and Walker, G. (2013) School holiday shake-up brings unintended consequences, published in The Conversation, October 24, 2013. Changing the length, timing, or coordination of school holidays would have a big impact on the ways in which daily lives are scheduled, and hence on the timing of when energy is used. De-synchronising school holidays would have tangible, but unintended and unanticipated consequences for energy demand.

Large organisations, like hospitals, can reduce demand and peak loads by analysing the energy and mobility-related consequences of routine working practices and by modifying sequences and schedules.

Stanley Blue’s work on Institutional Rhythms is informed by the DEMAND Centre’s distinctive theoretical approach to the study of end use energy demand – that it is more usefully understood as an outcome of social and institutional practices. The close relationship between working practices and energy demand means the success of initiatives to shift peak load, or promote low carbon transport, ultimately depends on the capacity to modify the temporal rhythms of institutional life. Detailed empirical research at two large hospital sites will provide much-needed insight into the potential for such innovation.

  • Blue, S. and Spurling, N. (2017) Qualities of connective tissue in hospital life: how complexes of practices change. In Hui, A. Schatzki, T. and Shove, E (eds.) The Nexus of Practices: Connections, constellations, practitioners. London: Routledge PDF.  This chapter calls for a practice theory that starts with complexes of practices and focusses on the relationships between types of connections between practices. Building on analyses of how practices are temporally organised, this chapter works through examples of hospital life to situate those temporal rhythms in relation to the multiple qualities of connective tissue (including material-spatial, jurisdictional, etc. that matter for how complexes of practices and hence, the temporal rhythms of institutions like hospitals, change over time.

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