House of Commons Energy and Climate Change Committee The effect on energy usage of extending British Summer Time Written evidence Ordered by The House of Commons to be printed Thursday 28 October 2010 Published on 21 November 2011 by authority of the House of Commons London: The Stationery Office Limited £0.00 The Energy and Climate Change Committee The Energy and Climate Change Committee is appointed by the House of Commons to examine the expenditure, administration, and policy of the Department of Energy and Climate Change and associated public bodies. Current membership Mr Tim Yeo MP (Conservative, South Suffolk) (Chair) Dan Byles MP (Conservative, North Warwickshire) Barry Gardiner MP (Labour, Brent North) Ian Lavery MP (Labour, Wansbeck) Dr Phillip Lee MP (Conservative, Bracknell) Albert Owen MP (Labour, Ynys Môn) Christopher Pincher MP (Conservative, Tamworth) John Robertson MP (Labour, Glasgow North West) Laura Sandys MP (Conservative, South Thanet) Sir Robert Smith MP (Liberal Democrat, West Aberdeenshire and Kincardine) Dr Alan Whitehead MP (Labour, Southampton Test) The following members were also members of the committee during the parliament: Gemma Doyle MP (Labour/Co-operative, West Dunbartonshire) Tom Greatrex MP (Labour, Rutherglen and Hamilton West) Powers The committee is one of the departmental select committees, the powers of which are set out in House of Commons Standing Orders, principally in SO No 152. These are available on the Internet via www.parliament.uk. Publication The Reports and evidence of the Committee are published by The Stationery Office by Order of the House. All publications of the Committee (including press notices) are on the internet at www.parliament.uk/parliament.uk/ecc. A list of Reports of the Committee in the present Parliament is at the back of this volume. The Report of the Committee, the formal minutes relating to that report, oral evidence taken and some or all written evidence are available in a printed volume. Additional written evidence may be published on the internet only. Committee staff The current staff of the Committee are Sarah Hartwell-Naguib (Clerk), Dr Richard Benwell (Second Clerk), Dr Michael H. O’Brien (Committee Specialist), Jenny Bird (Committee Specialist), Francene Graham (Senior Committee Assistant), Jonathan Olivier Wright (Committee Assistant), Edward Bolton (Committee Support Assistant) and Nick Davies (Media Officer). Contacts All correspondence should be addressed to the Clerk of the Energy and Climate Change Committee, House of Commons, 7 Millbank, London SW1P 3JA. The telephone number for general enquiries is 020 7219 2569; the Committee’s email address is [email protected] List of unprinted written evidence 1 Department for Business Innovation and Skills, the Department for Energy and Climate Change, and the Department for Transport Ev w1 2 Mayer Hillman Ev w4 3 Lighter Later Ev w7 4 Dr Michael Morrison Ev w8 5 Harry Hayfield Ev w11 6 Saga Ev w12 Oral and written evidence Oral and written evidence (submitted by witnesses who gave oral evidence) has been printed as House of Commons paper HC 562 and is available in electronic format at www.parliament.uk/ecc. Oral evidence was taken on the following date: Thursday 28 October 2010 Page Dr Elizabeth Garnsey and Dr Simon Hill, University of Cambridge, and Alan Smart, Energy Operations Manager, National Grid Ev 1 List of written evidence from witnesses National Grid Ev 11 cobber Pack: U PL: CWE1 [SO] Processed: [18-11-2011 16:23] Job: 006471 Unit: PG01 Energy and Climate Change Committee: Evidence Ev 1 Written evidence Memorandum submitted jointly by the Department for Business, Innovation and Skills, the Department for Energy and Climate Change, and the Department for Transport The following memorandum provides written evidence from the Department for Business Innovation and Skills (BIS), the Department for Energy and Climate Change (DECC) and the Department for Transport (DFT) on the effect on energy usage of extending British Summer Time. The current summertime arrangements for the UK involves moving the clocks forward one hour on the last Sunday of March each year so that were are on Greenwich Meantime (GMT) +1 and then back an hour on the last Sunday of October back to GMT. While on GMT+1, this is classed as British Summer Time. The twice- yearly change in time occurs in accordance with EU legislation The 9th EC Directive on Summer Time which harmonised the dates clocks change across EU member states. In response to the Committees request for evidence in relation to the effects on energy usage of extending British Summer Time which would mean being on GMT +2 during he summer and GMT +1 during the winter, the following is provided. Summary 1. In summary, although we might expect overall energy use to be reduced by extending British Summer Time (“BST”) the effects are likely to be small in magnitude, and may even be uncertain in direction. The most significant effects are likely to be associated with lighting demand as demand switches from the evening to the morning. 2. However the evidence quantifying these effects is not strong enough to conclude either way what the impact on the overall demand would be. On the one hand the working day is more aligned with natural daylight leading to reduction in demand, however there are also complex behavioural factors to consider such as such as the fact that households may be more likely to turn lights on when it is dark than off when it is light. 3. Evening peak electricity consumption may flatten (i.e. peak evening demand shifts to the morning) as a result of extending BST during the winter months which could be beneficial to security of supply. However, evening peaks between Great Britain and France may become more aligned, with implications for prices and security of supply in situations of low generation capacity margin. 4. The impact on gas demand for space heating is likely to be limited, but a flattening of peak electricity consumption, could, depending on the relative fossil fuel prices, result in a fall in gas demand for electricity generation which again could be beneficial for security of supply. 5. The effect on carbon budgets is dependent on the change in overall demand and is therefore likely to be limited. To the extent that extending BST reduces energy consumption, this may reduce the cost of meeting the renewables target. DECC Introduction 6. Extending British Summer Time (“BST”, or “GMT+1”) would result in later sunrises and sunsets, when compared to a reversion to GMT during the winter months. This may affect annual and peak electricity and gas demand, and thereby carbon emissions and security of supply. This note sets out the potential effects that might be expected and the available evidence quantifying them. 7. Extending BST would be likely to lead to shifts in the pattern of demand for gas and electricity. However the extent to which this will lead to material changes in the level of annual or peak demand is not clear: (a) The impact on gas demand for space heating will depend on the extent that slightly increased demand from marginally colder mornings are offset by reduced demand from marginally warmer evenings. However the overall heat requirement remains the same suggesting that we would not expect any significant impacts on the overall level of demand. (b) There is likely to be a more significant impact on patterns of electricity demand due to potential changes to the usage of artificial lighting. The main effect would be a switch in artificial lighting demand from the evening to the morning. To the extent that the (traditional) working day would be more aligned with natural daylight, there may be an overall reduction in artificial lighting demand. A change in the pattern of electricity demand may indirectly affect the pattern of gas demand (for base- and peak-load electricity generation). 8. The following sections: — discuss available evidence we have on the effect in the UK of extending BST on overall energy demand; — highlight specific additional considerations for electricity and gas markets; cobber Pack: U PL: CWE1 [E] Processed: [18-11-2011 16:23] Job: 006471 Unit: PG01 Ev 2 Energy and Climate Change Committee: Evidence — note the implications for carbon budgets and renewables targets; and — highlight other relevant considerations. Overall Energy Demand 9. As outlined above one would expect overall energy demand to reduce as a result of the change, and indeed a recent study (Hill et al, 2010)1 that considered the impact of moving the clocks forward in winter (from GMT to GMT+1) did estimate an annual saving of approximately 0.5 MtCO2e per year. 10. The analysis is based on actual half-hourly electricity data from the National Grid. The authors construct a demand profile by fitting observed weekday electricity demand to time, temperature, daylight (illumination) and baseline electricity consumption. By fitting observed data to a model, it is possible to forecast what the impact of changing the clocks (all other factors staying constant) would be on UK energy use. 11. The authors found the following: — During a trial period, in 1968—1971, where GMT+1 was applied year round, energy consumption was reduced overall. — The modelled results suggest that electricity savings would be observed throughout the period November to March. The emissions reduction associated with such a change is estimated at 0.45 MtCO2e per year. 12. However, there may also be complex behavioural factors that need to be considered, such as the fact that households may be more likely to turn lights on when it is dark than off when it is light. This effect could conceivably lead to an increase in energy demand as a result of the change which was found by studies commissioned by Defra from the Buildings Research Establishment (BRE) in 19902 and 20063.