Timing is Everything

Sept. 19, 2023, 5:52 p.m. • By Adam Forster

Unveiling the Secrets of Emissions Reductions

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In the realm of energy consumption, reductions are not always synonymous with extravagant costs. By implementing efficient systems and strategies, remarkable progress can be made. Let us delve into the domain of electricity usage, a fundamental aspect of every business. In this exploration, we will examine the intricate interplay between emissions factors and network demand. Additionally, we will shed light on the significance of comprehending user needs, as well as the potential of timing when it comes to achieving reductions. Furthermore, we will outline a comprehensive plan encompassing various aspects of this endeavour. This includes insights into the seasonal variations in network demand and carbon intensity, the fluctuations throughout the day, and the disparities between different regions. By arming ourselves with knowledge and making data-driven decisions, we can reduce our real carbon emissions.


If you are here just looking for simple reduction techniques, skip to the Reductions section. I also give Key Take Aways at the end of each section for those of you in a hurry.

Time of Year

Let’s first look at network demand over the year. As you would expect, demand is high in the winter and low in the summer. Furthermore, there is much lower variability in the summer presumably as people don’t need to warm their homes.

One interesting feature is the dramatic drop in demand in the approach to Christmas. To a certain extent this may contradict ones expectations; there is nothing more christmassy than turning that heating up, having a cup of tea, and getting cozy. However, as offices close and we all head home for the festivities with our families, we embrace communal living and, as such, radically increase our energy efficiency. My parents heat their home whether I am there or not. But I certainly don’t heat my home when I am away for Christmas.

Now let’s look at the corresponding carbon intensity of the grid. Below is a plot showing the carbon emissions per kWh of electricity generated. We call this ratio an “emissions factor”.

The plot is certainly quite sporadic. Fluctuations in weather cause large fluctuations in the emissions factors. There are two features, however, that I would like to draw your attention to.

  1. As with the demand, the emissions factor falls off a cliff during the festive period. A big reduction in demand means that the green energy resources are sufficient (or more sufficient) to cover our energy needs. As we will see later, periods of high demand must be responded to by grid operators and more energy must be produced. But how to respond; you can’t ask the wind to blow harder or switch the sun on (certainly not in this country). Instead grid operators utilise the energy sources they can control; fossil fuels. Therefore, spike in demand ⇒ spike in emissions factors.
  2. Given what I just said, you may say, “Dr. Adam, if low demand implies low emissions why don’t the emissions factors drop in the Summer?” That is a good question, and one we will return to later.

Key Take Away

  • Demand and Emissions factors are correlated
  • Both drop for Christmas as communal living leads to greater energy efficiency

Time of Day

Now let’s look at the time of day. Below is a plot of the average network demand at each time of day throughout the year. Now this looks very interesting!

Demand is low in the night and high in the day; no surprises there. It ramps up rapidly early in the morning, stays high until tea time, and then as all those kettles start to boil, dinners get cooked, and millions of individual homes are heated, demand spikes before gradually trickling down for bed.

Now let’s look at emissions factors. As before, the emissions factor rockets up as we all wake up and go to work. But unlike before, the emissions factor rapidly falls again. Increasing sunshine and wind speeds increase natures contribution to our electricity production taking over from dead dinosaurs. However, as the light starts to fade and demand starts to spike, emissions factors tear upwards again as mother nature goes on to power someone else's grid network and leaves us to fend for ourselves. Of course, as bedtime approaches and demand recedes, so too does the emissions factor.

Key Take Away

  • Emissions vary throughout the day
  • They are low at night and at midday

Time of Day for Different Seasons

But is this average over the whole year really representative. After all, the weather is very different throughout the year.

Below is the network demand throughout the year broken down by season. As we saw earlier summer has lower demand and winter has higher with spring and autumn being somewhere in between (no surprises there). But now let’s turn to the emissions factors.

Here we see an inversion; it is summer with the high emissions factor and winter with the low. This is because, alas, we do not live in a mediterranean paradise. We live in a wind swept Atlantic out crop in Northern Europe. So, you will not be surprised to hear that the majority of our renewable energy does not come from solar, but from wind (contributing >25% to the UK’s energy supply). Therefore, those gusty walks to work on cold February mornings are not in vain. They are saving the planet (in more ways than one). On the other hand, next time you’re enjoying a cold one in the garden on beautiful summers day, just know that the energy required to cool that cold one was roughly twice as carbon intensive. This, incidentally, is the solution to point 2 in the first section.

Another interesting feature, is that although summer is higher, they all seem to converge around midday. In summer solar comes in to do its part. However, this is only short lived as, soon enough, the sun sets on another day. The wind, however, keeps grafting come rain or shine, massively reducing the night time emissions factor.

Key Take Away

  • Emissions factors vary by season
  • Winter is both high demand and low emissions bucking the usual correlation
  • This is due to wind energy

Time of Day for Different Regions

One last plot. It turns out that not all regions have the same emissions factors (I could not get hold of regional demand data so we will have to make do with the emissions themselves).

As you can see below, there is huge variability between these 14 regions of Great Britain. Coming in with very low marks, we have South Wales. An over reliance on coal is to blame there. With a staggeringly low emissions factor we have North East England. Energy lines connecting this region to Norway, the green energy capital of the world, bless this region with incredibly low emissions through out the year.

Key Take Away

  • Emissions factors vary by region
  • South Wales is exceptionally poor and North East England is exceptionally good


Based on the information provided, here are some recommended reduction techniques:

  1. Knowledge is power (pun intended). Install a smart meter to monitor and manage electricity usage effectively.
  2. Shift energy consumption to off-peak hours, such as at night or midday when demand and emissions factors are lower.
  3. Consider moving production or establishing operations in regions with low emissions factors, such as Scotland and North England.

By implementing these techniques, businesses can make significant progress in reducing their carbon footprint and contributing to a more sustainable future.

Furthermore, there is a great opportunity for the northern low energy regions, such as North East England, to become low carbon economic powerhouses. With their access to green energy sources and favourable emissions factors, these regions have the potential to attract sustainable businesses and drive the transition to a low-carbon economy.


We've journeyed through an extensive landscape of data, unraveling the intricacies of electricity demand and emissions factors across different times and regions. What this exploration underscores is that the key to sustainable energy consumption isn't merely in reduction but in intelligent timing and strategic geographical choices.

The seasonal and diurnal fluctuations in network demand and emissions factors present both challenges and opportunities. By understanding these rhythms, businesses can adjust their energy consumption patterns to capitalise on periods of lower emissions factors. This doesn't just benefit the bottom line—it significantly contributes to global sustainability objectives.

But it's not just about when you consume energy, it's also about where. Regional disparities in emissions factors could catalyse a paradigm shift in how we think about location-based advantages. Regions like North East England could very well become the next havens for eco-conscious businesses.

So, let's pivot the dialogue from a discourse centred on restrictions to one that recognises the dynamism and opportunities within our existing frameworks. With the right data and the willingness to adapt, a more sustainable future isn't just possible; it's within reach.


Thanks to National Grid ESO and Carbon Intensity Org

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