September surprised bringing news that creates both sympathy and rejection at the same time: Brussels proposes the end of the daylight-saving time. Around 4.6 million people participated in a non-binding survey on the continuity of this measure and nothing less than 80% of the participants were against shifting their time twice a year.

On Friday, September 14th, the results were confirmed. Brussels informed that countries of the European Union must notify by April 2019 (a period of just over 6 months), if they choose to stay in summer or winter time.

It is not my intention in this post to discuss whether this change is indeed negative or positive (hundreds of studies so far have not been able to draw a clear conclusion). There are many and very complex factors to be considered: economic, environmental, health…

What I will try in the following lines is to study the impact that this change could have in the companies’ energy bills, giving a general, clear and objective vision. If you are the person in charge for an industry concerned about how this possible change could affect your bill, you should continue reading.

The beginning:

It is believed that Benjamin Franklin was the first to suggest some measures to save energy through adapting how we live to the solar time, introducing the daylight-saving time. The measure began to be taken seriously during the First World War, where Germany opted to reduce the number of hours of artificial lighting to save coal and use it in acts of war. After the Second World War, the time was not changed until the 1974 oil crisis, where energy saving measures became especially important.

Daylight saving time in the world:

In Western Europe, all countries except Iceland change their time twice a year. Worldwide, only 40% carry out this practice.

Source: Wikipedia

The saving:

If we are still keeping the daylight saving time (although for not too long), it is because it has traditionally been considered that it generates saving, although in the last years this has been very questioned. One of the most mentioned official studies is the one made a few years ago by IDAE (Institute for Diversification and Energy Saving), according to which daylight saving time allows us to save 5% of the lighting in Spain, which would translate into 300 million.

Does that mean that finishing with daylight saving time will make us pay more? Let’s see:

On the “Astronomy” website of the National Geographic Institute, we can access the sunrise and sunset times of any year and province we are interested in.

In the following graphs I have crosschecked the sunrise and sunset hours of Madrid for the year 2019 with 3 different time possibilities and with the start and end hours of a working day from 9:00 a.m. to 6:00 p.m:


1-Current time (GTM+2 in summer and GTM+1 in winter):



2-Keeping summer time (GTM+2) the 365 days of the year (the European Commission’s favorite option):



3-Keeping winter time (GTM+1) the 365 days of the year.


Considering the previous graphs, we observe that the time that best fits a working day of 09:00 to 18:00 would be the current one. It seems that the fact of had changed the time twice a year (with the headaches that it involves) has made sense.

I could be satisfied with this conclusion and be against ending of daylight saving time, but let’s go a little further.

Beyond the center:

In the previous study, we took as an example Madrid, it seems logical to take the center of the peninsula, but in Spain, companies and industries are spread throughout the whole territory. Let’s see how the same study would be if instead of Madrid we consider Barcelona:

1-Current time (GTM+2 in summer and GTM+1 in winter):



2-Keeping summer time (GTM+2) the 365 days of the year (the European Commission’s favorite option):



3-Keeping winter time (GTM+1) the 365 days of the year.


If for Madrid the current time system is what best fits with the “standard” working day schedule, for Barcelona it looks like it would rather fit better to stay in the GTM+2 schedule (summer time) throughout the year.

I could repeat this exercise with each geographical area, and I would have a different result each time. The issue starts to be not so clear.

Workday schedule:

If it is inaccurate to consider a single geographical zone to carry out the study, just as inaccurate is to consider a single working day schedule.

We must bear in mind that, for industries with double or triple shifts, being in one or another time is basically irrelevant, since we will take advantage of all the daylight hours no matter the time.

On the other hand, companies, increasingly, offer their employees continuous or flexible schedules very different to the traditional.

All this, along with the fact that there are many businesses such as restaurants, supermarkets and many more that do not conform to the standard schedule, distort the idea that with daylight saving time we take better advantage of the daylight hours.

Lighting expenditure:

Another question to evaluate the impact that changing or not changing the time may have, is the impact of lighting on our budget.

Let’s see the impact that lighting has on electricity budget by sector:

Association of Energy Efficiency Companies (A3e).

While in commerce and offices the lighting can carry a very important weight, for the industry is different, estimating that it can affect 15% of the electricity bill. Therefore, when we talk about the 5% saving in lighting, we talk about a 5% saving on the percentages of the previous table. In the case of the industry, the saving estimated by the IDAE thanks to the daylight saving time would affect 0.75% of the total electric bill.

In addition, the advance of technologies in the field of lighting, led by low consumption systems such as Led and the greater use of control and regulation systems, also make the weight of lighting expenses have changed since the studies we base on when calculating saving thanks to daylight saving time.

Adjustment of systems:

Over the years, more and more tasks are automated, and often automated in base on the time. The change of time supposes headaches when setting schedules for certain tasks and can generate several problems for companies twice a year.

Indeed, in the electricity market, the so-called hour 25 of the last Sunday of October in which energy must also be bought and sold, is a little chaos and makes us to dedicate a big effort and an important loss of time adapting tools if we want to avoid disaster.


The situation has changed a lot since the years in which our current time system was implemented to achieve energy savings.

As we have seen, the schedules and the way of consuming energy as far as the companies and industry are concerned, has changed significantly and the premises taken years ago may not be correct nowadays.

If we add that today work schedules and needs are increasingly diverse according to the consumer and the area, the utility of keep daylight saving time is very questionable.

Personally, and after the brief analysis, I do not see that ending daylight saving time is going to imply a handicap to our companies and industries, but rather it can be something beneficial.

For the next few months, it is necessary to decide whether to keep the summer or the winter time, so we will keep listening news about this matter.

Will we regret this decision in the future? I think it is unlikely.

Ismael Abordan | Energy Consultant

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