Session 2010-11
Publications on the internet

To be published as HC 562-i




Energy and Climate Change Committee

The effect on energy usage of extending British Summer Time

Thursday 28 October 2010

Dr Elizabeth Garnsey, Dr Simon Hill and Alan Smart

Evidence heard in Public Questions 1-98



This is a corrected transcript of evidence taken in public and reported to the House. The transcript has been placed on the internet on the authority of the Committee, and copies have been made available by the Vote Office for the use of Members and others.


The transcript is an approved formal record of these proceedings. It will be printed in due course.

Oral Evidence

Taken before the Energy and Climate Change Committee

on Thursday 28 October 2010

Members present:

Mr Tim Yeo (Chair)

Dan Byles

Albert Owen

Christopher Pincher

John Robertson

Laura Sandys

Sir Robert Smith


Examination of Witnesses

Witnesses: Dr Elizabeth Garnsey, University of Cambridge, Dr Simon Hill, University of Cambridge, and Alan Smart, Energy Operations Manager, National Grid, gave evidence.

Q1 Chair: Good morning and welcome. We thought, as we are all here, we would start a few minutes early. As you know, this is a oneoff session for this Committee but we thought it was timely as it is this weekend coming up and there is another attempt to introduce a Private Member’s Bill also coming up in a few weeks’ time. If we can reach any conclusions on the basis of what you are going to tell us, we might or might not decide to take some public action. Some of us are very committed to taking action privately and individually in public, but we have not yet reached that conclusion as a Committee. I think you will find this morning that there is a divergence of views amongst the members here.

Anyway, thank you very much for coming in. Would you just like to start by introducing yourselves? Dr Garnsey, do you want to kick off?

Dr Garnsey: Yes. I am Elizabeth Garnsey. I am Emeritus Reader in Innovation Studies in the Department of Engineering at Cambridge.

Alan Smart: I am Alan Smart. I am the Energy Operations Manager for National Grid, responsible for the operational forecasting of demand and operational policy for the National Grid system in Great Britain.

Dr Hill: I am Simon Hill. I am a Research Associate in the Department of Engineering and I work mostly on statistical methodology rather than energy aspects itself.

Q2 Chair: Thank you very much. Would you just like to summarise or give an overview of your research and the methodology you have used?

Dr Hill: Sure. The approach we have taken has been to look at just data straight from the National Grid about overall consumption. So you have these consumption profiles through the day where you see, obviously, quite low consumption in the early morning, rising up to a level, then having a bit of a peak in the evening and going back down.

We have looked at those profiles both from before Daylight Saving Time switches, during winter and after the Daylight Saving Time switches. We have tried to estimate what they would be like during the winter months, especially during November, December, February and March-because we had quite a bit of difficulty with January-just to get a feel for what the consumption difference would be were we to be on Daylight Saving Time rather than GMT between those months. That is the basis of what we have done. To do that sort of analysis we have used regression techniques, which I can go into in more detail if you would like.1

Chair: Do you want to come in, Robert?

Q3 Sir Robert Smith: Just on one thing. You have mentioned March.

Dr Hill : Yes.

Q4 Sir Robert Smith: The bit that I have never got my head around is what is the historical reason why clocks change about two months before mid-winter and three months after mid-winter? Have you done any comparisons of March and October because, obviously, October is on the nonchanged time and March is on the changed time?

Dr Hill: I should say I don't know anything about the first part of the question. I am afraid I don’t know why the particular dates have been chosen. As far as looking at comparing March and October, we have not done a strict comparison. We have just looked at the sort of reduction that we would expect in March.

Q5 Sir Robert Smith: It just seemed a very good data example. You have the country working on one time zone where the times are out of kilter with the other. March and October have the same amount of daylight for the day.

Dr Hill: I understand what you are saying, yes.

Q6 Sir Robert Smith: But used at different times of the day?

Dr Hill: Exactly.

Q7 Sir Robert Smith: Were you not tempted to look at that as a comparison?

Dr Hill: Those are the sorts of things we used in our analysis. So, basically, we would look at a particular time of day, a particular light level and particular prevailing weather conditions, temperature for instance, and we would say, "Okay, so if we have this time of day–if it is, say, 5pm today, it is reasonably dark and it’s a bit cold, and we know what the energy consumption is because we can observe it-what would it be like if it was to be 6pm right now?" Then we compare against other similar days with those sort of light levels and temperature at 6pm and say, "How similar do we think they would be to the current conditions?"-except for the time, obviously-and we use that to infer what we think the change in energy consumption would be like.

So, actually, the fact that we have the data from October, which, as you say, is very similar to March, is the sort of effect that we are actually looking at to compare and to get some results about what we want to find out.

Q8 Chair: One of the conclusions that you have drawn about the impact on energy consumption appears to be contradicted by the work done by the BRE.

Dr Hill: This is the report by Christine Pout?

Q9 Chair: I am not sure who the author was but it was commissioned by-

Dr Hill: It was commissioned in about 2005.

Chair: Yes.

Dr Hill: She used a very different methodology. She used a simulation-based approach where you basically try and come up with some sort of model of the energy flows in a particular house or a particular building-any sort of structure actually. You want to get a good crosssection of structures. You build up this model of the energy flows within all the different representative buildings and you try and extrapolate that sort of thing to the national picture.

To be honest, personally I have never had much to do with these sort of implementations but I am a bit concerned about that sort of approach because there are quite a few things that could go wrong. For instance, first of all, you have a very large number of variables associated with building up these models, so you have to make a large number of assumptions in order to construct what you are ultimately doing.

Second of all, you are looking to extrapolate these sorts of findings for individual buildings to a national representation and there are no real details in that paper about how that extrapolation was really done.

Third of all, you are looking to use this software, which is really designed to model individual buildings as opposed to coming up with this sort of analysis. So it is not being used for what it is actually designed for.

But the real two points that I was concerned about when I looked at that paper were, first of all, even in the Executive Summary it is talking about changing the time in the summer and changing the time in winter. You see there that they talk about 2% change over the whole year for energy consumption. But of that 2% change they are talking about slightly less than 1% change in energy increase in usage for the winter and slightly more than 1%, which must mean it is slightly more than 1% for the summer months. But, to me, that is not really intuitive and that is already starting to give me questions about the whole research. I do not want to "diss" it too much because I have never met her and I have not really done it, but these are the question marks I have in my mind about it. So you have got that sort of issue going.

So you have got quite a uniform day during the summer. It is light a lot of the time and I would have thought that shifting the time a little bit wouldn't have made such a big difference as it does in the winter, when you have got very constrained things that you are looking at. So I was a bit concerned about that for a start.

But the main concern I had was that when you look at that paper all the energy gains she is talking about come from nondomestic buildings. It is one thing to say, "Okay, I'm going to model houses and energy flows in houses". But houses are quite uniform; they are quite common structures. Domestic dwellings are quite-there is not a lot of variation, so it is probably-

Q10 Sir Robert Smith: But there is an A to G rating if you get it re-assessed by a surveyor.

Dr Hill: It is probably quite straightforward. I am sorry, I didn't quite catch that.

Q11 Sir Robert Smith: There is an A to G rating available for houses, so there must be a variety.

Dr Hill: Sure. There is a variety of houses but I think she would have taken that into account. But the thing is that houses are quite straightforward to model on; there's not a lot of variation between them. But with regard to nondomestic buildings, you have shops, you have places like this, you have places like universities and you have hospitals. You have a wide variety.

When you look at the details of the work, you find that in her first appendix she has spent a very large amount of time looking at these domestic dwellings. There are 20 pages of appendix on domestic dwellings but there are only a couple of pages on nondomestic dwellings. It is the nondomestic dwellings that are giving you all the energy changes she is talking about. So there are a lot of questions that come to my mind when talking about this particular approach.

Dr Garnsey: Could I just add that the data that are being used in the BRE report are simulated data. They are illustrative data-that is, invented data. When you do a simulation of that kind your outputs are going to represent the input assumptions that you made. In fact their assumptions don't reflect empirical evidence on energy use over the course of the day. So the data are not real. The assumptions don't coincide with empirical evidence, and the findings are out of line with the findings in the literature. We looked at 23 studies and only three of them had findings that were similar; they were out of line with the great weight of evidence from other studies of clock time.

But the most useful research is from the US in 2007 because they extended their Daylight Saving period by four weeks-three weeks in the spring and one week in the fall. They then had real data to compare before and after the clocks were advanced by an hour.

The finding was that there was a reduction in energy use after clocks were advanced by an hour of 0.5% of the average daily demand. Interestingly, this is very similar to what was found in 1970 in this country after the trial period, where it was also found that there had been a reduction in energy use of 0.5% of daily national demand. Those methodologies are both using national statistics rather than the buildingbased statistics of the BRE report.

Q12 Chair: In the work you have done more recently have you tried to break it down with the impact on different parts of the UK, because obviously, even in a relatively small country, we have quite a diverse experience?

Dr Garnsey: No. We looked at data for Great Britain as a whole.

Chair: Right.

Q13 Sir Robert Smith: When you say Great Britain, Northern Ireland didn't quite fit?

Dr Garnsey: Just England, Wales and Scotland.

Q14 John Robertson: I was a bit concerned when you rubbished the previous report. I have got to say your knowledge of housing is poor, to say the very least. Did you look at the fact that working patterns have changed-you mentioned the 1970s-and how they are changing for the future as well, and the fact that the working day isn't just a 9 to 5 job any more? It is actually practically a 24-hour job, depending on what kind of industry you are in.

Dr Garnsey: We looked at the energy demand profiles over the course of the day and-you are quite right-those have changed considerably over the years so that the before/after data that we have from 1970 is not going to apply in a similar way to the present. That is why we did our analysis on the most recent data which, when we did this work for the National Grid, was data for 2001-08. We looked at the energy profiles over that period.

Q15 John Robertson: Have you looked at what the possibility of future consumption would be? We have spent a long time in this Committee looking at things like electronic cars and how we expect electricity to possibly double in decades to come. Have you built that into your equation?

Dr Garnsey: I think that Alan Smart from the National Grid is the person to answer that question because we were looking at the figures for 2001-08 rather than doing forecasting.

Alan Smart: We have looked at the effect on the peak demand. One of the issues that you have with this is that the complexity of the modelling is down to-if you look at the peaks of the day, there are three peaks during the profile: there is a morning peak during the summer, a teatime peak round about 5 o'clock and then you have the darkness peak, which obviously moves.

The morning peak and the teatime peak are relatively straightforward to forecast in terms of the demand that is being made up. The darkness one is very difficult and this is why it is quite difficult when you try and work out what the savings are going to be. The reason for that is that outside of the peak winter, when it's dark everywhere during December and January, the time at which that peak occurs is very much driven by individual behaviour. Basically, what happens is that once you get past about September, the time at which it gets dark, week by week, is moving forward about 15 minutes. You get to the period where we take the clock change and you put the clocks back, and what you do then is that that effectively moves the teatime peak on top of the darkness peak.

That darkness peak is very difficult to forecast. The reason for it is that it is very dependent on weather, because on a bright day you will get a darkness peak at a different time from a day when it is cloudy.

The other interesting effect on that is the way people respond. Believe it or not, it can actually be triggered by television programmes. If I paint a scenario for you: you are sat down at home and it is a relatively normal day; it is not particularly bright and it is not particularly dull. You have sat down; you have not got your lights on yet. You have sat down and you are watching a television programme. One of the effects that we see, particularly as you get towards the end of September, is that this darkness peak can actually get triggered by the end of the television programme because as the programme ends not only do you do what we are very used to forecasting-TV pickups: you get up and go and make a cup of tea-but what happens now is that as you get up it has got dark while you have been sitting down watching the television programme. So you get up, you put your lounge light on, you put your hall light on, you go and put your kitchen light on and then you go and put the kettle on. So that darkness peak is getting triggered by the end of a television programme. Those are different every day. It is different if the weather is different.

So once you get outside of that winter peak period-once you get into those "shoulder" months of February and March, and September and October-it is very difficult to forecast exactly what would happen on a yearbyyear basis.

Coming to your question about the future, most of the work that has been done on that is around analysing-in an ideal world, what you would like to do with the things like electric cars is to fill in the troughs: to try and move demand away from the peak and actually fill it into the troughs. So that is an area of work which is being looked at.

Q16 John Robertson: But you have already said that people are actually creatures of habit, so would they fit into your trough?

Alan Smart: I think the real issue comes down to, what would it take to get individuals to change? There, you are into the smart metering. Would there be tariffs at different times of the day? How much would it take for you to change your lifestyle to move your electricity demand from one period to another period?

The other issue that is different from what we would have seen in recent years is that the peak demand today, because of the recession effects, is quite significantly lower than what we have seen in the past. It has come off by about 5%. That decay has stabilised and it has started to plateau. Again, what you have to try and do then, forecasting forward, is to decide what sort of growth figures you should use in terms of the demand.

The real challenge for us is that we can see an effect outside of the peak months of December and January. To actually say what that effect would be, to quantify it-there would be a reduction, but to actually quantify it is very difficult because you have to decide what the weather pattern is going to be and how human behaviour will change.

Our analysis, which is different from the detailed analysis that Dr Garnsey has done, is that we have only looked at the peaks. We have just said, "What would happen to the peak demand if we didn't change the clocks?" We can see an effect on the shoulders, but only a very marginal-if any-effect actually on the peak because it is going to be dark in December anyway.

Q17 Albert Owen: Can I just go back to what you said about the fact that you took the whole of Great Britain? Obviously we are not looking at the UK picture here because Northern Ireland is the most westerly point of the United Kingdom. So there are differentials; you accept that. Do you think that it would have changed any of your conclusions if you had looked at Northern Ireland or if you had looked at microclimates in some parts of the United Kingdom? There is a big variation between my constituency in the west of Wales and the south-east of England here. Do you think that if you had had detailed analysis of different parts of the United Kingdom then the outcomes would have been different?

Dr Garnsey: We were asked to put the pragmatic findings of the operations managers at National Grid on a statistical footing. We did this at a national level, looking at the national figures on electricity demand; the interest being what would happen, if we advanced the clocks by an hour, to demand for electricity as a whole, and could we also predict what the price impact would be of a change in the clocks by advancing them by an hour? So, no, we didn't look at the consumption in particular areas because, in a sense, that wasn't the research problem that we were addressing. It was more, "Would there be, for GB as a whole, a reduction in electricity demand by advancing the clocks?" We found that there would be.

But it is interesting that there has never been proof that putting the clocks back has any benefit for energy. It has always been the default time-solar noon-which is a historic and geographic standard. It wasn't justified by any concern with saving energy.

When Daylight Saving was first introduced in 1916, some people said we would save coal by having Daylight Saving in winter too. But at that point it was felt that clock time at solar noon was almost sacred, and the fact that we could save coal in winter was not sufficient to justify Daylight Saving in winter.

Q18 Albert Owen: Dr Hill, you said that you took in temperature, and obviously there is a big difference in temperature between different parts of the United Kingdom?

Dr Hill: I think you are right. I think you would see slightly different effects all over the United Kingdom. That is just my opinion. I have not looked at any data about this.

Q19 Albert Owen: So you didn't factor this into your research?

Dr Hill: No, we looked at the big picture.

Q20 Albert Owen: Can I just move on? The Grid mentioned about the impact an extension of BST would have on winter demand, but you only looked at the peaks. Is that correct?

Alan Smart: That is correct, yes.

Q21 Albert Owen: You only looked at the peaks. So what would the extension be, overall, for the winter demand?

Alan Smart: In terms of what would be the reduction in energy terms, just basing it on the peak, we think in the shoulder months we would look to take off something like 1,300 MW off of the peak.

Q22 Albert Owen: A bit louder, sorry?

Alan Smart: It is about 1,300 MW in the shoulder months. It is on average approximately 1 GWh of energy per day.

Q23 Albert Owen: What is that in households? Can you tell the layperson what that means? How many power stations do we need to produce that?

Alan Smart: That is about one large power station over the peak or, one large power station running for one less hour a day

Q24 Albert Owen: How many households, roughly, would consume that kind of electricity? You are an expert so I am asking you.

Alan Smart: Let's have a think. I must make sure I get the zeros in all the right places. That is going to be somewhere in the region of 100,000, something like that.

Q25 Albert Owen: 100,000 households of electricity, fine. Can I just move on to a response you gave, Dr Hill, to the Chairman with regards to the BRE survey? You said you were critical of it for certain reasons, but are the behavioural patterns that they looked at something that you looked at?

Dr Hill: We didn't look at that stuff at all.

Q26 Albert Owen: Sorry, you didn't?

Dr Hill: No.

Q27 Albert Owen: Is the reason for that-

Dr Hill: In the literature basically you see two different approaches. You see this simulation approach, which is based on simulating people's behaviour and that sort of thing, and you see a topdown approach that we have taken. It happens that we have taken this topdown approach because the data that we have from the National Grid were the data that you would apply that sort of approach to.

Personally, I feel more comfortable with the topdown approach. With the simulation approach, if you look in the literature, they are also the approaches that produced the largest predicted changes in consumption. So we have done a bit of a review of the literature and there are about five papers we have looked at which have done simulation approaches. Generally, you see the changes they predict are of the order of 1% or 2% of energy consumption, whereas often the topdown approaches, if anything, are more conservative. They often predict changes of the order of fractions of per cent, which is what we have done. So you can look at it as being a more conservative approach as well, in my view.

Q28 Albert Owen: Would you like to add anything, Dr Garnsey?

Dr Garnsey: Yes. It is desirable to use real data because if you are doing a model in which you use illustrative data then you are just doing the working out of your data.

What we did was to use a prize-winning forecasting equation and we trained this equation accurately to predict demand. Once it was able to predict known demand we held all the determinants of demand constant but, as Dr Hill said, shifted the clock ahead by an hour, so all would remain the same except the clock change. Then we were able to compare demand that actually occurred over that period-2001-08-with the demand that would have occurred according to our prize-winning prediction equation, had the clocks been advanced. It was that comparison that yielded our findings.

We had over 200,000 data points. It took over 24 hours to run the algorithm through the data, so it was very data-rich analysis. If you compare that with a simulation which inputs illustrative data to say, "Well, if this is how people behave then this is what the consequence would be", you see that you are dealing with a different order of research.

Q29 Albert Owen: I have just one question, again on the grid. Again, in layperson's terms, next week the clocks will be going back. Will we see an increase in demand?

Alan Smart: Yes.

Q30 Albert Owen: Next weekend?

Alan Smart: If you compare, say, Tuesday evening's demand this week to the first Tuesday post the clock change, it will be higher-in the order of 1,000MW to 1,500MW.

Q31 Albert Owen: Psychologically people feel will colder and they will put their electricity on earlier?

Alan Smart: Psychology has a lot to do with it when people do it. You get what we term a "misery factor", and that is, it might not necessarily be colder, but if it is wet, damp and windy then people think it is colder and they turn the heating on and the demand goes up.

Q32 Albert Owen: The dog does not get exercised?

Alan Smart: No.

Q33 John Robertson: Just to clarify, how could you tell those figures if you take Britain as a whole? You can't exactly extrapolate the people in Scotland, because when we go to work in the morning and come home at night it is dark both times. So how can you tell the difference in areas like that?

Alan Smart: In terms of the total demand, Scotland represents about 10% of the demand. In terms of the increase for that period once those clocks have changed, it is pretty proportional. There is not a significant difference.

Q34 John Robertson: So being in the dark doesn't make any difference then? It is just the time of day?

Alan Smart: Once you get to the point where it is dark everywhere, there is not a great deal of difference. I accept that, if you were looking at next Tuesday, for example, then, yes, there would be a difference because, obviously, the effect is earlier in Scotland than what it would be in England and Wales.

Q35 John Robertson: So that’s my best guesstimate, but what you are saying is you don't really know?

Alan Smart: We have not analysed the significant difference at different times of the day.

Q36 Sir Robert Smith: The data are GBwide for the electricity, though, are they not?

Alan Smart: England, Wales and Scotland, yes.

Q37 Sir Robert Smith: Dr Garnsey, just one factual thing. What is the difference between solar noon on the easternmost part of England and solar noon on the westernmost part of the United Kingdom?

Dr Garnsey: Solar noon is a sundial technology, really, because an accurate sundial would point due north at solar noon. There are considerable differences in different parts of the country, and of course, it wasn't until the railways that this became an inconvenience and standard time was introduced so that-

Q38 Sir Robert Smith: I just wondered what the spread was across the UK.

Dr Garnsey: I don't know what the exact spread is, but we are a long, narrow country so there is a considerable spread, yes.

Q39 Sir Robert Smith: But if we are narrow there should be less spread because it is an eastwest phenomenon and not a northsouth phenomenon?

Dr Garnsey: If you are talking about the northsouth-

Q40 Sir Robert Smith: Northsouth-it is the same right from the North Pole to the South Pole.

Dr Garnsey: Yes, but there are shorter hours of daylight.

Q41 Sir Robert Smith: Shorter hours of daylight; I was asking about solar noon. That is an eastwest phenomenon?

Dr Garnsey: Yes, it is. I was thinking about the hours of daylight.

Q42 Sir Robert Smith: I was just thinking the country has an eastwest component, with the west of Northern Ireland and Lowestoft being quite far apart. I just wondered if we can find that somewhere else. I wondered also whether any research you know of had looked at gas demand, because obviously, energy consumption in this country isn't just electricity.

Dr Garnsey: The National Grid have looked at gas.

Alan Smart: In terms of the impact on gas, the biggest impact would be, if you are shifting around the electricity demand profile and a good component of that electricity demand is being met by gasfired power stations, then obviously that is having an impact on the gas demand. In terms of the impact on total gas demand overall, we have not done any detailed analysis on domestic impacts. That is not the sort of data that we have, so I couldn't give you an answer on domestic impacts.

Q43 Sir Robert Smith: And industrial use of gas?

Alan Smart: Industrial, again, is being driven by the manufacturing process during the hours that the parties operate in.

Q44 Sir Robert Smith: I suppose space heating for industrial buildings would have to come on tougher in the mornings if there is less-obviously, the temperature profile of the day would shift by an hour and therefore the business use of gas would be increased in the morning.

Alan Smart: Whereas electricity is balanced second by second, the gas demand is balanced on a 24-hour period. So when you move the gas demand around in a day period the total demand remains the same-

Q45 Sir Robert Smith: But if we as a Committee are looking at the energy saving benefits of shifting the clock, gas is part of the energy consumption?

Alan Smart: Yes.

Q46 Sir Robert Smith: It is quite a big part of the energy consumption of the UK?

Alan Smart: That is right, but what we say-

Q47 Sir Robert Smith: Even if you can't give us the evidence, we need to know if we are going to make a conclusion.

Alan Smart: All I can say is on a total gas demand basis, during a 24-hour period, we don't see a significant change other than that would be impacted by moving around the electricity generation from gasfired power stations.

Q48 Christopher Pincher: My questions are directed at Dr Garnsey and Dr Hill. You have done some research into British Double Summer Time-GMT+2- moving forward to the summer time now, but that is described as experimental methodology. I just wonder, what is experimental about it?

Dr Garnsey: The methodology that we used for the winter time effect was a wellproven method that has a strong track record but it requires comparable data, as you pointed out. For October and March we had similar hours of daylight. So we were able to look at GMT and GMT+1 for days when the hours of daylight were similar in order to make comparisons.

We didn't have any such data for GMT+2 because we have not been on GMT+2- that is, Summer Time plus an extra hour-since the war, when we were on that time to save fuel. So we had to do a more complex modelling exercise which didn't have a proven track record. But the findings were relatively consistent. So where we found that of 0.3% of daily demand could be reduced over the winter using one methodology, on the other methodology we found that 0.27% of the daily demand could be reduced over the summer.2 It is just that we wanted to make the proviso that one of the methodologies had a proven track record, and the other was a new method that we devised.

Q49 Christopher Pincher: So would you equate it with your view of the BRE methodology?

Dr Garnsey: No, because we were using real data. We were using actual data, whereas the BRE was using simulated or invented data.

Q50 Christopher Pincher: But it was also experimental.

Dr Garnsey: It was also experimental, but it was experimental using invented data as opposed to experimental using real data.

Q51 Christopher Pincher: So how robust are the conclusions that you reached using this experimental data? I think you suggest that there is an average daily saving of 0.27%?

Dr Garnsey: The inference can be made from behavioural patterns. I think it's always very good to look at activity patterns over the course of the day and see that it gets light at 4.30 in the morning on 21 June, and people are not using that electricity for the first few hours. However, it is getting dark at about 10 o'clock on 21st June and people are using electricity for another hour then. That is the longest day but, if we look on either side, we see a considerable disparity over the summer months between hours of daylight and activity patterns of the population. So our findings are consistent with inferences that you can draw from the current disparity between the population's activity patterns and-

Q52 Christopher Pincher: What are those disparities?

Dr Garnsey: The disparity is that it gets light long before people are up and about, but it gets dark while people are still using electricity in the evening.

Q53 Laura Sandys: Can I just follow on from that and, also, in some ways following on from Robert's point? Parts of France are actually on the same longitude, aren't they, as Britain and they will have Double Summer Time because they also change their clocks? Could we not be using some of their data, as well, to assess behaviour and also energy consumption, because none of us are actually aligned according to time and longitude right across Europe? When you start to get to Portugal, one has some of the similar issues too. So there must be a lot of data out there about exact behaviour, exact energy consumption per capita, per-

Dr Garnsey: That is a very interesting question but, in fact, electricity consumption behaviour is very country-specific. They have a very different pattern of electricity demand in France with their long lunch hour, and they work later in the evening. Their profile is quite different from ours so it is difficult to-

Q54 Laura Sandys: Do we get that behaviour as well if we change the hours?

Dr Garnsey: I don’t think we get out that much. We go on eating "al desko" unfortunately.

Christopher Pincher: We don’t drink at lunchtime - yet.

Laura Sandys: There you go-absolutely.

Q55 Christopher Pincher: What is the National Grid's view of British Double Summer Time in terms of energy use?

Alan Smart: In terms of energy use we don't see that it would make a significant difference. In terms of forecasting it, any change that we make will bring with it the challenge that we've got to forecast what the demand is going forward, from an operational perspective and from the amount of reserves that we hold on the system.

The way in which we do it is all based on history. One of the things that you can reasonably predict is that, if you take the same day of the week, the same time of year and the same weather, the demand will be pretty close if you take into account any growth effects. So any move that we make will bring with it a challenging period until we get some of that data, but in terms of the effect we don't see that Double Summer Time will have a significant effect for us.

Q56 Christopher Pincher: If we align ourselves more closely, for example, with France, as Laura was saying, given that we get some of our energy from France, doesn’t the fact that we are aligned rather eat into capacity and peak usage periods across both the United Kingdom and France?

Alan Smart: I think that is a particularly interesting point. Things have changed significantly in terms of the relationships that we see between ourselves and France and the use of the UK/France interconnector today, compared with what you would have seen traditionally in the past. That is predominantly brought about by the market coupling, inasmuch as there are now half hour by half hour energy markets in France, as there are in the UK.

What dictates today the flow on the interconnector at any given time will be the price differentials between ourselves and France. So whereas if you were to look back five years you could traditionally see that you could be expecting to export during the afternoon period to France, as we moved into our peak you would expect it to go back the other way. It still happens slightly, but these days it is very much driven by the price differentials. If you look at the forward price curves going forward for this winter, at the moment the energy price in France for this winter is trading at a premium of about £5 a MWh. So if that was to stay right the way through for this winter, plus a proposed charging change that is coming in, it means that it is quite possible that over our winter peak, this winter, we could be exporting to France.

It will depend on how much surplus there is in each country. Obviously, as the margin for spare generation becomes tighter, the price for energy will go up and you would expect the flow to respond to that price. So if we saw that forward price differential reversed because, let's say, we've got colder weather in this country and the price on the day is trading higher in this country than France, I would expect to see the interconnector reversed and we would actually import over the winter peak.

So whereas, traditionally, in the past, the flow reversed according to the separation of the peaks, today it is very much because of the market coupling and half hour energy pricing and the trading that takes place on the interconnector. It is driven by price.

Q57 Laura Sandys: One of the things that you've made a quite strong point in your paper to us about is, if we make this change we are going to end up aligning our peak times with France-in some ways following on from what Christopher is saying. But France also changes its hours too. So why is that such a strong point in your argument?

Alan Smart: It is, really, looking back at history. Traditionally-

Q58 Laura Sandys: Because we will just move sequentially. We won't be aligned with-

Alan Smart: In terms of the alignment, you don't see a great deal of effect in a single hour period. It is more to do with the fact that you are aware of which country has got the spare generation and where its peak is occurring. So when they are aligned they will be at the peak at the same time, and when they are separated there will be a bit of an opportunity. But, to be honest, that is completely swamped by the price effect.

Q59 Laura Sandys: But why is it more expensive if we changed our hours than if we kept them as they are today? We are still one hour different from the French peak. If peak price is your issue, I can't see the difference between where we are now and where we would be if we changed.

Alan Smart: It wouldn't be that significant. It is completely reflected by the pricing.

Q60 Laura Sandys: So the pricing would not be impacted by a change in our system of hours?

Alan Smart: When the peaks are aligned the price would directly reflect it. When the peaks are separated you will be at different points in the price curve. When the peaks are aligned it would be the straightforward price for that half hour. When the peaks are actually separated, where there is a spare capacity, obviously you will be that little bit lower on the price curve, so you could see some sort of effect.

Q61 Laura Sandys: But then we also have the cost benefit of not having one extra large power station. That didn't really come through in your argument very clearly, that there are compensating balances.

Alan Smart: No, I accept that. If we had been looking at this two or three years ago, one of the things that you could be reasonably saying is that if we were able to trim that peak demand, then we would probably be able to avoid running very expensive oilfired generation, for example.

One of the effects that you have seen in recent years-for two reasons-is the recession effect on the demand, which has brought the demand down. The other thing is that you have started to get a growth in wind and you have started to get new gasfired power stations being built. So what you are actually seeing now is that the marginal plant that we will see this winter, that most expensive generator that we are likely to run this winter, is likely to be either gasfired or coalfired. Last winter was the first winter for very many years where we ran hardly any oil-fired generation just to meet the peak demand. There was some there for constraints but, in terms of actually meeting the generation or the actual total demand, we didn't run oil for that purpose.

So whereas in the past you could have looked and said there is a real price step change when you go from a coalfired generator to an oilfired generator, that is not likely to be there now because the marginal generators are most likely to be coal or gasfired.

Q62 Dan Byles: We have not had an actual trial, a multi-year trial, in the UK since the 1960s. My understanding is that the results of that trial were actually considered to be inconclusive. Do you think it would be possible to design a new trial methodology that would actually lead to some conclusive answers to some of these questions?

Dr Garnsey: It isn't the case that the findings were inconclusive. There were some very strong findings-findings of energy reduction of 0.5% of the national average demand, and the accident findings were about 100 fewer deaths on the road. What happened was that the data had not been fully analysed by the time a vote was taken in the House of Commons to end the trial. But, as the data came out subsequently, it became very clear that the trial period had considerable benefits both for road casualties and for energy use.

Q63 Dan Byles: So the White Paper in 1970 came out too early, you are saying, before a proper analysis had been-

Dr Garnsey: It came out before a full analysis had taken place, but even that White Paper was quite revealing of the benefits of the trial period.

Q64 Dan Byles: My understanding was that the White Paper stated it was impossible to quantify the advantages and disadvantages.

Dr Garnsey: It was thought at that time that 0.5% was not very important as an energy effect but, of course, this is cumulative. If you think about the amount of emissions that have resulted since that time, we are into 10 million tonnes of carbon that have been emitted because these figures build up cumulatively. We are now much more concerned about energy effects than they were in 1970.

Q65 Dan Byles: Has any work been done on what the format of a potential new trial might look like?

Dr Garnsey: I think what has been recommended by those in favour of a new trial is that in the October of the year of the trial, the clocks would not be put back. The following spring they would be put forward and thereafter we would be back to "spring forward, fall back", but an hour ahead of what we are currently.

Q66 Dan Byles: So we would have just shifted everything along by an hour?

Dr Garnsey: We would shift everything along. So there would be one autumn when we had no change, and thereafter we would have the same change as we do now but an hour ahead.

Q67 Dan Byles: How long do you think a trial like that would need to run in order to produce some meaningful data?

Dr Garnsey: Ideally five years, but three years would be useful.

Q68 Dan Byles: Do you agree, Mr Smart?

Alan Smart: I think you would have to strip out all of the weather effects, but in any period where you can compare one October or November with a previous November, we ought to be able to strip out the variables that you can and get to the numbers. So I would have thought three years would be more than adequate.

Q69 Dan Byles: Do you know if anybody has done any estimate of what the cost of such a trial might be?

Dr Garnsey: I believe the Department for Transport did an estimate that from the transport point of view, it would cost about £15 million.

Q70 Dan Byles: On transport alone?

Dr Garnsey: Yes.

Q71 Dan Byles: Presumably there will be other knockon effects across the board?

Dr Garnsey: Any change has costs, but we have to compare these costs with the costs of other ways of reducing our energy demand.

Q72 Dan Byles: But we can't compare the costs if we can't quantify them. So we would need to be able to quantify what the cost of such a trial might be before we can decide whether it was-

Dr Garnsey: Yes, indeed. That is a reason for further study.

Q73 Dan Byles: Do you believe that that is the logical next step-that we should move towards a new trial?

Dr Garnsey: I do indeed.

Q74 Dan Byles: Mr Smart?

Alan Smart: I think a trial would be the way to identify what the actual savings are, yes.

Q75 John Robertson: Needless to say I am not in favour of it, so let me be clear about that here and now, as one of the children who did go through it north of the Border back in the 1960s and the problems that we had of going to school when it was dark and coming home. There were problems road traffic accidentwise in our area because of that. That was back in the 1960s.

What kind of investigation and research has been done on the roads and the usage nowadays, because we do find that the highest time of accident is the school run? If the school run is permanently in the dark, we could expect the school run problem to be exacerbated in a trial like this.

Have any other investigations and analysis been done on the social aspects of moving the clocks, particularly regarding families and the usage of cars? Has any analysis been done on the effect that that would have on tourism? Working on the theory that it is darker for longer in the UK, I know from getting the bus in London that there are plenty of foreign people getting on the bus who are tourists with their maps. Would they be inclined not to come here because it was darker for longer in the morning? Working with tourists’ stats, has there been any investigation on that?

In other words, what I am saying is, other than the energy aspect of the investigation and the money that might be saved there, has there been any form of analysis done on any other types of effect that we would have in the UK, before we even think about going down the road of having a trial period?

Dr Garnsey: The Royal Society for the Prevention of Accidents has been doing research for years and comes out very strongly in favour of advancing the clocks by an hour, because the research that they have commissioned-and road casualties data in Scotland, indeed-show that there is greater intensity of road usage in the early evening than in the early morning.

Q76 John Robertson: Is that not associated with the school run again, and picking up children from school?

Sir Robert Smith: The school run isn't in the early evening.

John Robertson: There is an early evening school run, because there are the afterschool care clubs.

Dr Garnsey: What the Royal Society for the Prevention of Accidents analysis has looked at is net accidents morning and evening. So, taking into account any increase in accidents in the morning from darker mornings and the reduction in accidents in evenings, they find, in study after study, that there would be a reduction in road accidents from an extra hour in the evening because that is the time when road usage is at its most intense, including in Scotland.

Q77 John Robertson: And the other aspects?

Dr Garnsey: Tourism work has been done for the tourist boards, BALPPA and other tourist agencies. They are very strongly in favour of an extra hour of light in the afternoon because that is when tourism can benefit most from an extra hour of light.

Q78 Sir Robert Smith: I know the financial sector is not exactly the most popular part of our economy at the moment, but it still plays a part. Where do they fit in in terms of time-zone management, because their marketing strength for London as a financial sector is positioning between the Far East and the US? If we shift our time zone, does that have any impact on their trading arrangements and their handover arrangements? Would they adapt their behaviour by their work patterns shifting to keep closer to the States?

Dr Garnsey: I haven't looked at that, but it is clear that our major trading activities are with our European partners, and that there would be very considerable benefits in being on the same time as our major trading partners, as anyone who has had to get up very early to go to a meeting on the continent knows. There is probably more activity in terms of physical trade with Europe than with America.

Q79 Albert Owen: I want to link some of the issues that you just raised with my colleague, the social and behavioural, with energy. You talked about tourism being benefited and I can see that. You also mentioned, Dr Garnsey, the fact that there is nobody around at half past four in the morning in the summer, but in the evenings I suppose it is quite attractive to think we could have a barbecue at 11.30 and not be watching telly. So those are the benefits.

But with regard to tourism, have you quantified some of the figures? Have you been able to do that, because a lot of sporting events now, for instance, use floodlights in the winter? Traditionally they are winter sports and they are using that. What about the savings there, not just regarding accidents but the actual energy that can be saved for schools? I am talking about not the Premier League clubs because they can afford it, but other sporting activities and actually drawing people out of the home and using less electricity domestically in their homes. But as you said, Dr Hill, the nondomestic buildings are not very energy efficient, and yet they've got heating on and they've got lighting on in an evening. Has that sort of calculation been looked at?

Dr Garnsey: I don't know of calculations but the Football Association and a large range of sporting associations are strongly in favour of an extra hour of light for sporting activities in the early evening and late afternoon.

Q80 Albert Owen: The boost to tourism has been identified?

Dr Garnsey: Yes. The tourist lobby is very much in favour of an extra hour of daylight in the evening.

Q81 Albert Owen: But there will be energy savings as well for those organisations?

Dr Garnsey: I have not seen calculations to that effect, but we have looked at the overall savings, which is, after all, what is most pertinent.

Q82 Albert Owen: But, broken down, there would be, in your opinion, energy savings as well as economic benefits?

Dr Garnsey: The floodlights would have to be on for an hour less in the evenings, yes.

Q83 Christopher Pincher: This is not strictly in the purview of this Committee, I think, but I am interested in the answer if you can give it to me. Nobody likes getting up in the dark; certainly I don't. I just wonder whether you have done any analysis on the potential for increased absenteeism if you have darker mornings for longer.

Dr Garnsey: The analysis of behavioural responses has not been systematic but one factor that has been brought out is that depression rates seem to increase when the clocks go back and that Seasonal Affective Disorder symptoms spike when the clocks go back. So it does seem that those people who are prone to depression or Seasonal Affective Disorder are more adversely affected by the early onset of dark than by dark in the early morning.

Q84 Christopher Pincher: But there is no analysis that has been done around people not going to work, or as early as they should go to work, if it is a dark morning?

Dr Garnsey: I haven't heard of any studies of that kind.

Q85 Chair: Given the research that you have done, do you think it is the case that moving the clocks in the way we are contemplating will help to achieve our emissions reduction targets?

Dr Garnsey: I don't see how they could fail to do so but it is difficult to calculate by exactly how much.

Q86 Chair: Some people will argue that because power generation is already covered by the EU emissions trading system, the incentive effect of a move of this sort isn't really very great because the companies are watching more what they've got to do to keep within the EU limits.

Dr Garnsey: It seems to me that the argument is that if we reduce energy demand, then we reduce emissions and we are more likely to achieve our emissions targets, whatever the carbon trading impact might be.

Q87 Sir Robert Smith: The only problem is, if we reduce our emissions in the trading market we reduce the price of emissions and therefore allow the Europeans to make more emissions for the same price. So the net effect of Europe is-

Dr Garnsey: One needs a trial period for real data because one can't speculate as to what those impacts might be.

Q88 Chair: Could this change be regarded as an energy efficiency measure, do you think?

Dr Garnsey: I beg your pardon?

Q89 Chair: Do you think this change could be presented as an energy efficiency measure?

Dr Garnsey: Well, a better alignment of activity patterns with energy use measure.

Q90 Chair: Right. It is 40 years since the last experiment was done and, as you mentioned earlier on, unfortunately Parliament voted before the impact of that had been fully explored. Things have moved on in a number of ways since then and, obviously, we are more concerned about use of energy generally. It is a much higher priority now to try and use it efficiently and reduce demand.

But there are some other things that are available in the way that our transport infrastructure has altered quite radically since the late 1960s. We've now got the prospect of smart meters coming in and so on. Is it possible to take account of all that in the research that has been done?

Dr Garnsey: Forecasting the future is a very difficult undertaking. I think the pragmatic work that they do at the Grid is probably as reliable as anything that we have because they have real problems to solve and find ways of addressing them. So I would-

Alan Smart: I think our analysis shows that the real difference is in those shoulder months-it is in the October, November, February and March. That is where the real difference is. The Scottish question is, once we get into December it is dark everywhere anyway, so it is the same for everybody. But you can make a real difference in those shoulder months.

Q91 Albert Owen: I am just a bit concerned about Great Britain only and not Northern Ireland. If you are looking at it, would you say an experiment should be just for Great Britain, and Northern Ireland would have to align with the Republic of Ireland, or are you suggesting that in any experiment in the future Northern Ireland should be taken into the equation with the rest of Great Britain?

Alan Smart: I would expect Northern Ireland to have a similar demand profile shape as the rest of Great Britain. So I would expect to see a similar impact in those shoulder months in Northern Ireland that you would see in this country.

Q92 Sir Robert Smith: Was there any study done of Portugal, because Portugal used to be on European time and then-I don't know why-switched back to British time? Do you know anything about the history of that change and if-

Dr Garnsey: I do. It is a good illustration of how there is always more vocal objection to change than there is support for it, because when the change was made in Portugal everyone who didn't like it protested, whereas those who did like it didn't lobby. The Portuguese example was cited in a House of Commons Library Report as relevant to Britain but, in fact, they are so much further south that they already have the advantage of that extra hour of daylight at peak time-what for us would be peak time-even without putting the clocks forward. So it is really the northsouth issue that is critical there, which is why I was bringing that up in relation to your earlier question.

Q93 Chair: Mr Robertson is not here now but, just to be absolutely clear, you referred to the RoSPA research on road accidents. Am I right in saying that even in Scotland it was demonstrated that, actually, the impact of the change was to reduce accidents?

Dr Garnsey: That's right.

Q94 Chair: But a slight increase in the morning was outweighed many times by a big decrease in the evening?

Dr Garnsey: It was found that there were 100 fewer deaths on the road, of which 40 were in Scotland. Since Scotland is only 10% of the population, they benefited more than any other part of the country. There were some questions about the data but then, later, there was further analysis done in the 1990s and they also found that Scottish accidents would benefit from advancing the clocks.

Q95 Sir Robert Smith: Mr Robertson, though, had a go at me. I suppose back then there were a lot less afterschool clubs than there would be now, which alters the profile of when children come home.

Dr Garnsey: One thing was that the newspapers all, understandably, gave a lot of attention to tragic early morning accidents. No attention was paid to the fact that there were fewer accidents in the afternoon. So it was only the morning accidents that attracted attention.

At that time the lights were not switched back on in the morning, whereas now, with computerised lighting, the lights can be switched back on in the morning so it shouldn't make any difference whether it is the morning or evening. That light switching effect no longer applies today.

Q96 Laura Sandys: I am just wondering what the current view from the NFU and from the farming and agricultural sector is, and the differentiation between those in England and those, let's say, in Scotland, Wales and possibly Northern Ireland: how they have different views, and whether they have different views.

Dr Garnsey: The NFU have said that they don't object to the clocks being advanced because their new technology-

Q97 Laura Sandys: Because they used to be quite against it. There was a sense of-

Dr Garnsey: They were very much against it but they are no longer against it. But, obviously, there will be some farmers who will object. There is always going to be some objection to any change.

Q98 Dan Byles: I am just curious to know, what do you think are actually the biggest negatives to making a change, because the impression I get seems to be that organisation after organisation are starting to line up behind such a move? It does start to seem that there is perhaps quite significant pressure towards this, but are there significant disadvantages or negative effects anywhere in the system?

Dr Garnsey: There are advantages for early-morning workers, clearly. We really need real data from a trial to see what the other effects were. It is possible that an extra hour of daylight in the evening in the summer might result in more petrol emissions because people use their cars more. That is the sort of thing that we need real data on. It is very difficult to speculate about that ahead of time.

There would also be the possibility of costs attached to computers having to have the clock-time changed. No change of this kind is cost-free but we would have to compare it with the much greater costs of an extra power station, for example.

Chair: Good. Colleagues, are there any more questions? No? Okay. Thank you very much indeed for coming in. We much appreciate that.

[1] Note by witness: “ S.I. Hill, F.Desobry, E.W.Garnsey, Y.-F.Chong, 2010, The impact on energy consumption of daylight saving clock changes, Energy Policy 38/9, 4955-4965 ”

[2] Note by witness: “Yu-Foong Chong, Elizabeth Garnsey, Simon Hill and Frédéric Desobry, 2010 forthcoming, Daylight Saving, Electricity Demand and Emissions: The British Case Chapter 18 in Jamasb, T. and Pollitt, M., Eds. (2011), Electricity and Heat Demand in a Low-Carbon World: Customers, Citizens and Loads, Cambridge University Press.”