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Monitoring all-electric retail stores

This article concerns a retail chain in the UK whose stores are a mix of gas-heated and all-electric buildings, any of which could also be using air conditioning to some extent. Their analysts had the task of defining expected-consumption formulae based on historical consumption and degree-day data. The question was what driving factors they should choose: heating degree days, cooling degree days, or both?

For any store with a gas supply, the answer was reasonably obvious: we could expect gas consumption to depend on heating degree days. Furthermore, electricity in those cases was likely either to be driven by cooling degree days or to be weather-insensitive.

For all-electric stores in general the picture is less clear but the likelihood had to be that heating was the main driver in these cases. This was based on the fact that they were more likely than not to behave like their gas-heated counterparts. So my advice was to treat heating degree days as the primary factor driving week-by-week variation in consumption. After that the only question to answer was whether there was any cooling influence, and that can be answered quickly by looking at the consumption profile through the year. Three scenarios are likely:

1. Higher consumption in winter only. This suggests there is no cooling influence;


2. Higher consumption in winter and summer than in spring and autumn. This clearly indicates a cooling load;


3. Broadly constant consumption all year. This also implies a cooling load.


Why does scenario 3, which shows no seasonal changes, imply the presence of cooling load? Precisely because higher winter consumption is not evident. These buildings must in fact be using heating, but they must also have a seasonal demand for cooling which overlaps the heating season, and adding the two together creates the flat profile.

Worst league table format ever?

The chart format on the left is a reconstruction of something I saw in an energy reporting system based on a generic platform who shall remain nameless (you know who you are). It is being used here to represent the relative total energy consumptions of a number of establishments. Although admittedly it is better than a pie chart, it is still one of the least user-friendly designs I have ever seen. The person who devised it should be ashamed of themselves.

Why have remote labels with a colour-coded key, when the labels could just be put alongside the bars they relate to as shown on the right-hand example? Especially as with so many entries the colours are hard to discriminate even for a user with perfect colour vision.

The right-hand version of the chart gives the identical information perfectly clearly with bars of the same colour, the additional advantage being that, if required, one specific item can be highlighted in a contrasting shade as shown. Oh, and it won’t matter if your computer monitor’s colour rendering is a bit off.

Project profile: training and support for software developer

My client here was an energy management bureau allied to a facilities maintenance company. They’re working for a retail chain with several hundred UK sites and they needed to develop not just useful energy reports for their customer’s regional managers, but also an effective method of detecting and prioritising exceptional adverse performance, so that avoidable energy waste can be spotted and remedied in a cost-effective manner.

Working on software code with the developer

We did the training in two parts, both via Zoom video link. On the Tuesday we went through the key generic principles using a pared-back version of my one-day training course on monitoring and targeting. Then on the Friday, after they’d had a chance to experiment with some data on an Excel-based toolkit, we got to grips with the software platform that they use. The screenshot shows me working with their managing director and software developer to build some of the key functionality that they will require.

Generic refutations of bogus products

I have prepared some product category briefings are intended to assist readers who want to reject suspicious product offerings in circumstances where other people in their organisation need to be convinced that the products are worthless.

Supplementary air removal for heating systems (i.e. other than the conventional devices already fitted)

Burner anticycling controls

Magnetic fuel treatment

Radiator boosters

Super-thin insulation

Voltage reduction (or “optimisation”)

Heating water additives

If readers have other product categories which they would like me to add, or specific suspect offerings, please get in touch.

Zoom versus vroom

Participating in a remote meeting for one hour generates the same emissions as driving just 580 metres. That was my conclusion when someone asked me what were the relative environmental impacts of remote and in-person meetings. Here’s how I approached the question…

We’ll start by estimating the energy intensity of data communications. We know from an Ofcom study that in 2018 the average UK fixed broadband connection was using 240 GB per month, and if we assume £30 per month was the typical tariff, that works out at £0.125 per GB. Now let’s assume that this price covers the operator’s costs and that, pessimistically, 50% of that cost is for electricity which they were buying at (say) £0.15 per kWh. This implies an energy intensity of £0.125 x 50% / £0.15 = 0.42 kWh per GB.

But how much data is there in a remote meeting? Fortunately we can get a good direct estimate from the sizes of session recordings. My two-hour on-line events have typically resulted in recordings of around 500 MB, which must be the equivalent of all the data broadcast to each participant (as a sense check, that’s 250 megabytes per hour, or about 0.55 megabits per second bandwidth). To be conservative let’s add as much again for return traffic from each participant, giving a total of 500 MB (0.5 GB) per hour per participant.

At 0.42 kWh per GB that implies 0.5 x 0.42 = 0.21 kWh per participant-hour.

This only accounts for the communications element. To be fair we need to add the cost of central data processing and to do that I’m firstly going to guess that the server consumes 100 watts for the purposes of processing the meeting. Secondly I’ll assume that the meeting has four participants. That would imply 0.025 kWh per participant-hour, bringing the total to 0.235. The fact that it’s a small correction means the conclusions aren’t very sensitive to the number of participants. If we assume a grid carbon intensity of 0.3 kgCO2/kWh we arrive at emissions of 0.235 x 0.3 = 0.07 kgCO2 per participant-hour.

How does that final figure compare with car travel to the meeting? The average car in the UK emits about 0.12 kgCO2 per km, so attending an hour-long remote meeting equates, in emissions terms, to 0.07/0.12 = 0.58 km of car travel. Case closed.


This article first appeared in the Energy Management Register bulletin on 12 July, 2021. Subscriptions are free of charge: please follow this link. You can unsubscribe again from any issue.


M.E.P. event for energy assessors

Submitted by the Association of Midlands Energy Professionals 

The Association of Midlands Energy Professionals (MEP) invites you to join us for our FOURTH annual event for energy assessors and other energy professionals, under the title: “Gearing up for Change”.

With BREXIT behind us and the TRUSTMARK now up and running, MEES is having a significant impact on the type of work we do. WHOLE HOUSE RETROFIT, PAS2038, and THE FUTURE HOMES STANDARD are becoming even bigger drivers as the gathering momentum surrounding climate change is set to make 2021 a year of real involvement and opportunity for us in changing the behaviours of our customers.

We will be on the front line, giving advice and promoting change to UK consumers.

  • We will hear from a selection of keynote speakers who will be bringing us up to date on all the above and more. The speakers will include the leading lights from the Retrofit Academy, TrustMark, and the Accreditation Bodies.
  • There will be a selection of workshops to participate in. These workshops will give you tasters of the ‘state of art’ tools and techniques.
  • There will be a “BBC Question Time” style session where you can put questions to a panel of experts including the Accredited Bodies

This will be a full and informative day which will provide 5 hours CPD plus valuable networking with fellow assessors and other professionals.

  • Date: Wednesday 29 September 2021 (10.00 to 16.30)
  • Venue: SSDC HQ, Wolverhampton Rd, Codsall WV8 1PX.

The charge for the event is £50 for MEP members, and £60 for non-members. Subscribers to the Energy Management Register newsletter can join at MEP members’ rates using their customary discount code. There will be a £10 early bird discount for those booking before the end of August 2021.  Booking forms are available from

Case history – excessive cooling incident in a data centre


This story concerns a commercial data centre, and specifically its cooling system. The players are: (a) clients whose servers are housed in the centre; (b) a facilities operations team responsible for maintaining conditions in the server hall; and (c) a sustainability manager whose duty is to ensure that energy consumption is minimised. There is a service level agreement in place and the facilities team are contractually obliged to report regularly on the server-room temperature.

The sustainability manager regularly reviews consumption against weather-related targets, in order to detect excessive consumption. Specifically he uses the relationship between chiller electricity consumption and cooling degree days, as illustrated in Figure 1:

Figure 1: normal relationship between weekly kWh and weekly cooling degree days

The story

At the end of September 2020,  weekly consumption began to deviate from expected values. The first few weeks of abnormal performance are highlighted in Figure 2:

Figure 2: abnormally high weekly consumption is observed

Figure 3 is a control chart which shows that the deviation is not only statistically significant compared with anything previously observed, but it’s also persistent:

Figure 3: the control chart shows the difference between actual and expected consumption

At this point the sustainability manager challenged the operations team for an explanation. The problem turned out to be the location of the temperature sensor that was used for their routine service-level reports. It was not registering the actual air temperature at equipment level, but a higher value. To get around this problem the ops team had started overcooling the building to ensure that their temperature reports were within the specification.

The problem was ultimately rectified by relocating the sensor used for reporting, and reverting to the correct space temperature set point. Figure 4 shows how consumption then came back within its normal control limits:

Figure 4: once the situation was fully resolved, the difference between actual and expected consumption drops back

Decarbonising heat: expert speakers on heat pumps

We will have two real experts on heat pumps addressing our afternoon conference “Decarbonising heat – practical realities” on 8 July, which will focus on the non-domestic market and the lessons that can be learned from real-life installations.

Ben Whittle is a technical manager from the Energy Saving Trust. He has been working in the world of renewables for 20 years, and has previously worked for companies designing and installing solar thermal, solar PV, biomass and heat pump systems to megawatt scale. 

John Cantor started out manufacturing and installing bespoke heat-pump systems during 1980s and 90s. He was system inspector for the first UK grants through BRE and was also on the MCS working group. He’s an honorary member of the Ground Source Heat Pump Association and author of ‘Heat Pumps for the Home’.

As well as heat pumps we’ll examine the realities of biomass installations and consider the prospects for hydrogen. More details at

Decarbonising heating: opening speaker

Jan Rosenow

Delighted to have Jan Rosenow opening our afternoon conference “Decarbonising heating – practical realities” on 8 July. Focussing on the non-domestic market, our speakers will discuss real-life experience with biomass boilers and heat-pump systems, and draw lessons for future projects. We’ll also hear from an expert on hydrogen about how that might be introduced into the national heating-fuel mix, and we have allowed plenty of time for questions from the audience.

Full details are at