Highlights from the Energy Management Register newsletter

7 JANUARY 2018


Reduction gearing is common where the driven equipment needs to run at a fraction of the speed of the electric motor which powers it (commonly just under 1500 or 3000 RPM when the supply frequency is 50 Hz). Belt drives can achieve the same but both belts and gears incur mechanical energy losses and require maintenance.

In some circumstances it is possible to re-engineer things with the driven equipment (a ventilation fan, for example) directly coupled to its motor, with the motor run at low speed by means of a variable-speed supply set to a low frequency. As well as avoiding the transmission energy loss, this dramatically reduces maintenance requirements and increases reliability.

Indeed for fan applications up to about 12kW, the conventional induction motor may beneficially be substituted by an electronically-commutated motor which itself has inherently better energy efficiency.

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5 JANUARY 2018


“Brigadoon” was a 1940s Broadway musical about a mythical Highland village that appears in the real world for only one day a year (although as far as its inhabitants are concerned time is continuous). Its plot concerns two tourists who happen upon this remote spot on the day that the village is there. The story came to mind some years ago when I was struggling to deal with energy monitoring of student residences whose weekly fuel consumption naturally dropped during vacations... Or should have done. I realised I would need two different expected-consumption formulae, one for occupied weeks and another for unoccupied weeks, the latter using degree-days computed to a lower base temperature. In each case, therefore, I split the data history into two: one for term weeks, and the other for vacation weeks. Each history thus had very long gaps in it, but there is no objection to closing up the gaps so that in effect the last week of each term is immediately followed by the first week of the next and likewise for vacations. For the purposes of cusum and other time-series analyses, the data must be sequential (in the right order) but not necessarily consecutive.

This strategy made the single building into two different ones. Somewhat like Brigadoon, the ‘vacant’ manifestation of the building for instance only comes into existence outside term time, but it appears to have a continuous history.

A similar approach can be used in various industrial monitoring scenarios. For a fuller article please see EnManReg.org/brigadoon or get in touch if you'd like advice on a specific application.

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29 JANUARY 2018


In situations where it is necessary to keep a building's outer doors open, you will sometimes find "air curtains", fans which blow a sheet of air down across the width of the doorway. These are an effective way of preventing dust and insects getting in through the door: they are entrained in the outer layer of airflow, and where the jet hits the floor it splits, with the outer layer discharging the contaminants back outside.

Some suppliers of air curtains claim that they conserve energy as well. The basis of this claim lies in what would naturally happen in an open doorway in still conditions, namely convective circulation in which warm air at high level flows out to be balanced by cold air flowing inwards at low level. This effect will be especially marked with high doorways. The claim for air curtains is that they disrupt the flow of escaping warm air, forcing it down to floor level where the jet splits, with the warm inner layer returning inside.

However, even in still conditions there is a problem here, because the fan is drawing air from high level inside and at floor level only half of it returns inside. 50% of the internal air drawn into the fan is diverted outside when the jet splits at floor level. A further problem with pedestrian doorways particularly is that the air curtain usually needs heating to prevent the perception of cold that the air's velocity would create. If the building actually doesn't need that heat, it is all a waste of money. Even if it does need heat, half is still wasted because it ends up outside.

In windy conditions the argument for air curtains as heat barriers really breaks down. A moving sheet of air is simply not as effective as a door. If there is any differential pressure whatever, that sheet of air will be displaced, and the problem is exacerbated if there are open doors or windows on the far side of space - or extract fans. In one memorable instance I visited a restaurant that operated an open-door policy. Their air curtain had a 20kW heater that ran continuously, but the downjet did not reach the floor: at about 60cm it turned inwards along with a layer of cold air at floor level, thanks to the kitchen extract depressurising the space.

Postscript: follow-up from readers included one who said that air curtains can work as a barrier against excess humidity in hot climates, a claim that was borne out by another who said they worked well keeping hydrocarbon fumes out of the shops on filling-station forecourts.

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11 JANUARY 2018


Most kinds of energy performance indicator are not up to the task. In industry, the most widely-used metric, kWh per unit of output, is all but useless because its value is naturally variable, increasing at low outputs and vice versa because of the effect of fixed overhead consumption. These changes mask the truth: poor performance at high output can perversely appear better than efficient operation at low output. Meanwhile people are no better off in the world of data centres, where the prevailing convention is to use 'power utilisation effectiveness' defined as the ratio between total electricity consumption and power delivered to the I.T. equipment housed in the centre. This metric varies at the mercy of the weather, misleadingly making performance look worse on hot days.

Furthermore, if you operate a process whose energy consumption is influenced by more than one driving factor, you are completely stuck as there is no single thing to divide consumption by.

The answer is to compare actual consumption with what you'd expect it to be under prevailing conditions. Just as, for routine exception reporting, you should evaluate and cost the DIFFERENCE between actual and expected consumption, to construct a robust and stable performance indicator you take the RATIO of actual to expected consumption to give what we call the 'Energy Performance Coefficient' (EnPC). EnPCs can be applied in any context, are inherently unaffected by variations in factors like throughput and weather, easily cope with consumptions affected by multiple drivers, and can even be numerically scaled to mimic the useless traditional performance indicators that they replace.

For a fuller explanation of EnPCs you can download a more detailed paper here: vesma.com/downloads/enpc-rev01.pdf

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8 JANUARY 2018


Prompted by a recent enquiry about 20-year average degree-day figures, it might be useful just to review what these averages are for and how they relate to 'current' and 'standard' values.

Let's start with the 'current' figures. These are values published on a weekly or monthly basis, region by region, and they reflect the actual weather. Their purpose is to provide an index against which your actual fuel consumption can be compared as part of ongoing routine monitoring. For example in the Midlands the heating degree-day value (base 15.5C) was 21.7 in the week to 6 October 2017. Successive values can be added together to give annual totals; these are one of the ingedients required if you are trying to normalise your annual consumption. For example in the Midlands the total heating degree days (base 15.5C) for the year to September 2017 was 1,939.

For normalisation purposes you also need a figure for the 'standard' weather year. There is a single standard number of heating degree days for any given base temperature (likewise for cooling). To enable correct normalisation between regions and from one year to the next, these 'standard' degree days are fixed values that do not vary by region. For example the standard number of heating degree days (to base 15.5C) has always been 2,463 for anywhere in the country.

Lastly when we want an indication of expected future weather for a given month in a particular region we typically take the average of the last 20 corresponding results. For example taking the Midlands, the average degree-day value (base 15.5C) over the last 20 Januaries was 334. Twenty-year average values really have no other use than forecasting demand. They vary from one region to another but change only slowly, so they are typically only updated once a year and the new set supercedes the old.

Here are some useful links:

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Amid the headline hype about the meteoric rise in the "value" of bitcoins it is easy to miss a significant energy story. The process of "mining" the coins consumes a vast amount of computing power... Not least because huge numbers of miners are continually doing the same intensive processing simultaneously, even though the output from only one of them will actually be used by the system. As a result, the annual consumption of electricity associated with bitcoin mining and transactions already matches that of Morocco and every bitcoin transaction now uses over 250 kWh. There is a load of fascinating reading on this topic at the Digiconomist web site.

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20 NOVEMBER 2017


A piece appeared in "Energy World" this month about the Berlin Festival of Light, where a 'kinetic pavement' has been installed supposedly to harness energy from passing pedestrians. An article along similar lines appeared two years ago on the website of the Institution of Mechanical Engineers. This helpfully showed a display screen connected to such a system installed in Brighton, stating that 54,267 steps had generated 217,028 watt-seconds. I hope all my readers can confirm for themselves that this equates to a mere 0.06 kWh.

In 2009 Sainsbury's installed a kinetic plate at their Gloucester store to take energy from customers' cars as they approached the car park. An article in the Guardian claimed that it could generate "30 kWh per hour". Yeah, right... I calculate it would take traffic of the order of eight hundred thousand cars an hour to do that -- assuming 100% conversion efficiency (see http://www.enmanreg.org/kinetic-plates/)

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Thermal energy storage can be beneficial for a variety of reasons. In air conditioning for instance, by levelling cooling demand it can reduce the capacity of chillers that one needs to install. Moreover, chillers run at night will not only tend to be more energy-efficient because of the colder ambient air, but electricity prices will be lower.

Ice storage is one of the techniques used in these circumstances because freezing water stores a lot of cooling energy relative to just changing its temperature: the heat removed in chilling 80 kg of liquid water by one degree would match the amount absorbed by making just one kilogram of ice. This latent heat effect can be achieved at other temperatures by substituting other materials for water. The process is generically known as 'phase-change' energy storage.

Naturally, like many genuine techniques, phase-change energy storage crops up in dubious offerings as well. I recently heard of a decorative wall covering containing a phase-change material with a melting point of around 22C, which its vendors claim would stabilise room temperatures and thus somehow save energy. Would in-room thermal storage be likely to save energy? Here are four scenarios:

• Scenario 1: the room temperature varies, but does not cross the product’s melting point. Here there will be no effect.

• Scenario 2: the control system maintains the room temperature continuously at or near the product’s melting point. Again, no effect.

• Scenario 3: cold weather, intermittent occupancy: say the room starts unoccupied with temperature below product melting point. Room occupant arrives and activates heating with set point above product melting point. Temperature rise is interrupted while product melts; this (a) delays the time at which set point is achieved and (b) stores heat which is later released (for no purpose) after the room is vacated and heating turned off. Result will be increased fuel consumption and possible occupant dissatisfaction.

• Scenario 4: hot weather, intermittent occupancy: suppose room starts unoccupied with temperature below product melting point. Heat gains cause temperature rise: just past the product melting point, it absorbs heat, so internal temperature is held steady for a while and peak room temperature is thus achieved somewhat later. Room occupant later arrives and activates cooling with a set point below product melting point. As temperature passes product melting point, product dumps (unwanted) stored heat into the space, delaying time at which set point is achieved. Result: possible customer dissatisfaction but no energy saving because the product never actually prevented heat getting into the space in the first place, so it still needs to be pumped out.

The vendors have taken a known technique, phase-change energy storage, and 'co-opted' its reputation. They also liken the effect to 'increased thermal mass'. This is sneaky. Many readers will have heard of thermal mass in buildings, and to hear it cited as one of the benefits of a product subtly fools us into assuming that it is an advantageous feature (why else would they mention it?). In fact, of course, slower thermal response will in some circumstances be the wrong thing to go for.

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30 OCTOBER 2017


This is a postscript to last week's item about power factor correction (PFC) capacitors. Stephen Barker, one of the speakers at next month's MAVCON17 conference, wrote that it is highly recommended to use 'detuned' PFC these days because electronic equipment, which is becoming prevalent, generates harmonic distortion - high-frequency components superimposed on the 50 Hz AC supply. Harmonic currents head directly for the low impedance offered by the capacitor and as a result standard PFC capacitors often fail very quickly indeed. Adding a correctly designed detuning reactor solves the problem. Detuned PFC is about twice the cost of standard PFC so isn’t heavily promoted - but subject to the careful evaluation of the practicalities and commercial viability, can still be a worthwhile investment.

My friend Kris Szajdzicki of ND Metering meanwhile drew my attention to another possible adverse effect of poor power factor: voltage drop. He wrote that this is known to have a serious impact on variable-frequency drives (particularly older ones) and to increase the effect of harmonics. Another argument in favour of power-factor correction.

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27 OCTOBER 2017


"Poor power factor" is the phenomenon whereby alternating current and voltage get out of step, leading to less real power being delivered than is implied by just multiplying volts by amps. Or, more realistically, leading to higher-than-necessary current being needed to generate the same real power.

This doesn't waste much energy as such (although line and transformer losses will be higher) but it does lead to higher transmission and distribution charges and will limit the maximum power you can draw from your supply. The solution is to fit capacitors, passive components that counteract the effect of things like electric motors that make the alternating current lag behind the voltage. I've posted a video on Youtube that illustrates both the problem and the solution with a mechanical analogue: https://www.youtube.com/watch?v=Slmk91cWZuw

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24 OCTOBER 2017


In common parlance, an energy 'baseline' is a reference value against which future consumption is gauged in order to assess changes in performance. Typically, baselines refer to a chosen 12-month period and are either 'absolute' (meaning the total quantity of energy used) or 'relative', that is to say expressed in terms of a metric such as kWh per unit of manufacturing output. Neither approach is particularly satisfactory in practice.

For a better way to look at it, start with the observation that consumption per week (or other interval) is partly constant and partly proportional to one or more independently-measurable driving factors such as production output, total duration of darkness, or the weather reckoned as degree days. This means you can derive a formula for expected consumption. Now the constants in that formula will have had certain values during the baseline period. That baseline FORMULA is rather useful because if we put into it the values of driving factors measured over some later interval, the result is an adjusted reference value against which to gauge actual consumption during that interval, with the effects of the variable driving factors automatically taken into account. As well as evaluating performance over a single week we can do it for a year or any other time-span.

Importantly, a baseline formula can be derived from data collected over any time-span. We are not compelled to use a year (even for weather-dependent loads) and known unrepresentative observations can be omitted if necessary. This is altogether a better approach. The paradigm shift? Treat 'baseline' as an adjective, not a noun.

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16 OCTOBER 2017


Automatic control should be high on the list when you are looking for opportunities to save energy; either introducing it where it did not exist before, or recommissioning and tuning it where it suffers from incorrect settings or has fallen into disrepair.

Building energy management systems are a clear candidate. Not only do they yield savings by regulating fuel and electricity use: they also help you to spot anomalous conditions in your plant (thereby avoiding energy waste through maintenance interventions) and their ability to record conditions through time provides invaluable diagnostic support. On lighting systems, auto control not only saves energy but gives the incidental benefit of creating an environment in which it is evident that the organisation cares about energy waste. In industrial contexts sensors can be used to start and stop conveyors, local extract ventilation, and other discrete items of equipment that do not need to run continuously.

Of course, the more you are saving through automatic control the more potential there will be for waste to occur when they go wrong, so routine monitoring and effective maintenance are critical.

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9 OCTOBER 2017


Electric cars and vans are becoming a feature of many company fleets and with the advent of clean air zones and vehicles with a 200-mile range it is a trend that is only going to increase. Organisations that have so far not monitored electricity consumption for battery charging are going to have to think about it and Chris Endacott, the instructor on our transport energy assessment courses, recommends getting systems in place sooner rather than later, and not just for the obvious reporting reasons. Last week we were discussing a scenario where an EV user could charge up at work and flog the electricity to their supplier at home if they had the right smart-meter tariff.

Chris tells me that DEFRA's GHG reporting guidelines now include factors for both battery electric vehicles and plug-in hybrid electric vehicles (can also be used for range extended electric vehicles). But these factors are only needed when actual energy use data is not available so now is the time to make sure charging of electric vehicles, whether on-site or at-home, is being metered. If you don’t meter it then then you won’t be able to calculate energy efficiency (km/kWh) or cost savings, much less detect pilferage.

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Anyone thinking about ESOS compliance will be faced with the need to commission or carry out energy audits or surveys. There are three generic approaches: checklist-based, product-led, and opportunity-led. The checklist-based approach suits simple repetitive surveys being done by less-experienced auditors; product-led surveys have a narrow focus on a particular technology, and typically apply where the energy manager has particular experience or a vendor has proposed a plausible solution (in which case one can leverage their expertise). Opportunity-led audits are those carried out by experienced auditors often with prior analysis of consumption patterns or after preliminary survey. These need wide expertise.

As for the categories of opportunity that will be found, these will be technical, behavioural, or procedural (i.e. to do with how the organisation manages energy). In the domain of technical opportunities the spectrum runs from things that are easy and inexpensive to those that are costly and disruptive. At the easy end we have, typically, opportunities to improve (or introduce) automatic control. Then we have the reduction of avoidable losses; then the pursuit of better component efficiencies (motors and drives for instance). Then, in manufacturing processes, we move on to the hard stuff: process layouts, process integration, and ultimately substitution of new alternative processes. One equivalent in the built environment might be better space planning leading to the closure of redundant buildings.

Opportunities arising under the 'behavioral' or human-factors heading would include: good housekeeping; overhauling maintenance practices; training; and improving vigilance and reporting. Finally under procedural opportunities we might find improvement of operating instructions, better scheduling, effective monitoring and exception handling and finally design feedback.

Going back to technical opportunities I have a tip. The most revealing question to ask, when looking at anything that consumes energy, is this: "How is that [insert name of object or process] controlled?"

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A reader from Nottingham sent me an advertisement for an automotive bolt-on gadget which injects hydrogen into the vehicle engine's air supply and is claimed to reduce emissions of particulates and nitrogen oxides (NOx) as well as giving dramatic improvements in fuel economy - up to 33% in one case cited in their July 2017 brochure.

If true, the improvement in emissions is a neat trick to have pulled off because generally there is a trade-off: higher combustion temperatures, which tend to reduce particulates, also unfortunately favour the production of NOx. I cannot comment on that, as the independent test house that they refer to has so far not responded to calls or emails. But what about fuel economy benefits? As with many such impressive claims, it pays to turn the argument on its head: getting 33% more miles per gallon after the intervention implies that 33% of your fuel energy was previously being wasted. But where was that lost 33% going? The intervention only addresses the completeness of combustion. So was the energy being lost in soot or carbon monoxide? If so, the engine would be belching black smoke and fail its MOT. Was 33% of your fuel pouring unburnt from the exhaust? I hardly think so.

What about the fact that the injected hydrogen is itself a fuel? The device produces hydrogen by electrolysis. The only energy you can get back from the hydrogen is what went in during electrolysis to dissociate it from oxygen, but the 18 to 48 watts of electrical power reportedly drawn by the device must call for additional fuel input several times that figure because of conversion losses through the engine and alternator. So the generation and subsequent combustion of hydrogen will have a negative impact on fuel economy, albeit very small.

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This concerns anyone currently certified to ISO50001 or thinking about doing it (for example as an ESOS compliance route).

ISO50001 is being revised, and the draft issued for consultation last week says, in a new clause 10.2, "The organization shall continually improve its energy performance". No such explicit requirement exists in the current version although thanks to ISO50003, which regulates their work in this area, accredited certifying bodies are not allowed to recertify an organisation that cannot demonstrate continual improvement. In fact thanks to ISO50003 new users cannot even get certified in the first place if they cannot prove performance has already improved.

However it is imposed, I think this new ‘hard compliance’ regime may have unintended consequences:

(a) High achievers could eventually reach the point where further marginal savings are uneconomic to pursue, effectively locking them out of recertification;

(b) As the potential for improvement tails off through time, the savings achieved become comparable to the margin for error. This effect, which the draft Standard fails to account for, makes it a lottery;

(c) Organisations that fail to gain recertification may well reduce their energy management efforts;

(d) At best, rational players have an incentive to postpone planned projects so as to ‘bank’ savings for later recertification cycles;

(e) At worst there is an incentive for users to use creative analyses to conjure savings out of thin air. This temptation is exacerbated by the moral hazard affecting auditors and certifying bodies that don’t want to lose clients;

(f) New users, and in particular those just starting to take energy management seriously, will be put off adopting ISO50001.

As any energy manager knows, just maintaining the savings you have previously achieved can be a hard trick to pull off and should in itself be recognised as a result. The original compliance regime was better in that respect because it allowed a measure of leeway in assessments.

ISO50001 was a good idea and it has worked well for many organisations, so I hope we will not see its user base eroded too dramatically. Meanwhile, given the new hard requirement, it will be critical how users set their baselines and evaluate their performance. That is definitely something I can help with.

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7 AUGUST 2017


Most verification of energy savings is done by a before-and-after comparison but, as last week's discussion on boiler anti-cycling controls reminded me, some types of energy-saving device can be temporarily bypassed or disabled at will. For these it may be possible to do interleaved on-off tests. The idea is that by separately averaging the ‘on’ and ‘off’ consumptions you can get a fair estimate of the effect of having the device enabled, with any distorting external influences averaged out.

There are two pitfalls, and the one which can be exploited for boiler anti-cycling controls is to do the test during a period of low load (when significant savings may well be apparent) and then extrapolate the results as if they would be achieved at normal or high loads, which is very unlikely.

The other pitfall occurs when, with the device enabled, reduced energy input results in reduced output which then has to be made up in the following interval when the device is disabled. This will notably tend to happen with voltage reduction in electric heating applications. During a low-voltage interval the heaters will run at lower power; the resulting deficit in heat output would then need to be made up during the subsequent high-voltage interval, making it look worse than the low-voltage one. To minimise this distortion, be sure to set the interval length several times longer than the typical equipment cycle time.

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23 JULY 2017


Scrabotnik (not his real name) asked my opinion of an email he'd received from someone selling bolt-on boiler 'optimisation' controls. These claim to reduce fuel consumption by altering the boiler firing pattern. Such devices are viewed with skepticism by heating control specialists (and indeed by each other's vendors) and they do make some pretty dubious claims, like savings of the order of 20%. They are also promoted with the pseudo-science and name-dropping that are the hallmarks of dodgy products.

As I have no concrete information on which to base a judgment, all I can do is answer in principle. My argument goes like this: in order to be able to save 20% without affecting the heating service, you must in the first place be using 25% more fuel than you strictly need, and using it in a manner that is avoidable. Assuming firstly that time and temperature control of the conditioned space are reasonably effective, that avoidable excess consumption must be occurring in the boiler room. But what aspect of operation is adding an avoidable 25% to your total year-round fuel consumption? If your boiler sequencing control is working, it cannot be standing loss from idle boilers. The only plausible culprit is ignition purge losses and indeed this is consistent with what the vendors say they are doing because ignition purge losses occur with each start-stop cycle and are a consequence of blowing ambient air through the combustion chamber briefly before and after firing. Increasing the length of the firing cycle to reduce the number of startups will reduce this loss. But are we really expected to believe that purge losses add 25% to your fuel consumption in their totality, let alone that proportion of them that you could avoid?

The implausibility of that idea can be seen by invoking Newton's Law of Cooling which says that heat flow between and object and its surroundings is proportional to temperature difference. When the boiler is firing, the temperature differential driving heat into the boiler water is hundreds of degrees; during fresh-air purging it will be a mere 60 or so. So on a conservative estimate a minute of purging will require no more than say ten seconds of firing to compensate. Now suppose your boiler is running at 50% load (30 minutes in each hour) and cycling on and off every 5 minutes with 2 minutes of purging each time. 12 starts an hour will call for 24 minutes of purging and as a result by my estimate 4 minutes of firing to make up the loss; that means we actually need to fire 34 minutes an hour rather than 30. Optimistically halving the number of starts would obviate 2 minutes of extra firing time, saving a mere 6%.

I am tempted to suggest that the household-name organisations that have been buying these things could profitably have sent their energy managers on one of my training courses ("Energy efficiency A to Z", or Certified Energy Manager). But then I would say that, wouldn't I?

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17 JULY 2017


Reader Adrian wanted to know if cusum analysis can be applied to energy used in data centres. In fact it can always be used if you have a valid way of modeling expected consumption based on prevailing conditions and I had two suggestions from my own experience.

Firstly take an uninterruptible power supply (UPS) installation. With metering both sides you can treat output energy as the driving factor for input energy. You would expect a classic straight-line relationship with a finite intercept (no-load loss) and a gradient just below 1.0 (conversion efficiency). UPSs can then be benchmarked against each other in terms of intercept and gradient separately, and for any individual case you could also detect unexpected excess consumption - for example the deployment of excessive UPS capacity, which will show up as an increase in no-load loss.

Secondly for cooling plant you will classically see dependence on two driving factors: cooling degree days and ‘rack power’. I have seen one user with duplicated computer-room air conditioning systems detect a monthly change in performance as they switched between one system and another on the first of the month (although to do that you need to be monitoring on a daily basis).

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27 JUNE 2017


How many ways can your mobile phone help with energy surveys and audits? (1) as a camera, obviously; (2) as a stopwatch: for example timing a 1-bar drop in air pressure when you turn off your compressors, to estimate leakage; (3) as a means of reading inaccessible rating plates or meter dials; (4) to co-ordinate 'drop tests' where one person does spot meter readings while another turns major loads on and off; (5) as a hand-held meter-reading terminal using a web service like MeterPad; (6) just as a browser to gather information on unfamiliar plant and equipment.

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12 JUNE 2017


The classic way we use automatic meter readings is simply to generate detailed consumption profiles. See my earlier articles on the heat-map display format, for example. But when it comes to routine reporting of exceptions and the diagnosis of anomalous energy performance, there's another key benefit to AMR.

To analyse energy performance (using tools such as cusum and regression) we must have data collected at successive equal intervals. I preach weekly as the sensible default. The group I was training on Thursday worked in dairy plants and are starting to adopt AMR with the advantage that they will be better able to synchronise their readings. They will also be able to take readings twice a day, at the end of each shift. However, their day and night shifts do different things: one does the manufacturing and the other does the cleaning. So my advice was to set up two separate parallel histories, one for each shift, aggregating both over the week and analysing them as distinct entities. The data for each will still be sequential and at regular intervals, but it will appear as if they are dealing with two factories: one purely manufacturing and the other continually cleaning itself. I expect what they will find is that the cleaning shift, being characterised by manual settings and operator discretion, will have much more variable behaviour and offer more scope for people-based initiatives, which will be thrown into starker relief by being evaluated as if production shifts had not happened.

This 'dual personality' approach to monitoring can be applied to buildings as well, notably in student accommodation, where the term-time and vacation consumption can be treated as if they were two separate establishments.

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6 JUNE 2017


Feedback from a recent 'Energy efficiency A to Z' course prompted me to review my material on electric motors in terms of whether one should replace or rewind failed motors. Conventional wisdom has long had it that rewinding is detrimental to energy efficiency; but it seems that view is out of date. A very thorough evaluation reported in 2003 (citation below) concludes that rewinding, when carried out in accordance with best practice, not only has a negligible impact on efficiency but may even improve it.

The decision whether or not to rewind actually comes down to factors which are quite case-specific and cannot be dictated by a one-size-fits-all policy. So for example the economic cost of waiting for a repair may force your hand, making replacement the only option. In non-urgent cases, an old motor might be replaced with a new one of substantially higher efficiency (and also possibly one better matched to the load if the original were oversized). But obviously if it is a special motor with a very long delivery time, rewinding may be your only choice.

Whatever the circumstances, if rewinding is contemplated it should be carried out in accordance with best practice, covering factors such as burn-out temperature, inspection and replacement of damaged laminations, and so on.

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31 MAY 2017


Regular readers will know of my obsession with False And Exaggerated Claimed Energy Savings (FAECES). But on two occasions I have come across perfectly legitimate products whose vendors have chosen to cite performance data which looks exaggerated, casting suspicion on something that actually deserves consideration. You need a bit of basic science to understand what they have done, but let me try to explain. In both cases, by coincidence, it comes down to latent heat.

In the first case we need to appreciate that the calorific value of a fuel - the amount of chemical energy it contains - can be quoted in two different ways. In the UK we habitually use the gross calorific value (GCV, or "higher heating value"). This accounts for the whole energy content, and because some of that energy is lost up the chimney, the efficiency of combustion (useful heat out divided by energy in) is always less than 100%. Typically with natural gas you cannot get much over 80% because the exhaust contains water vapour as a product of combustion, and for it to be in its vapour state it must have absorbed latent heat.

In continental Europe it is more common to state the net calorific value (NCV, or "lower heating value"). NCV is less than GCV because it disregards that part of the fuel's chemical energy that will be lost as latent heat in the exhaust vapour. Natural gas has an NCV/GCV ratio of 0.90; heavy oil, with its lower hydrogen content, has a ratio of 0.95 because it generates less water.

A glaring anomaly occurs when you have a gas-fired condensing boiler. Because it recovers the latent heat from the vapour in the exhaust, you may achieve an efficiency of perhaps 96% (dividing useful heat output by the gross calorific content). But should you choose to divide useful heat out by the NET calorific content, you'd get an efficiency supposedly of 106.7%, and that is what some reputable manufacturers quote. The result of this over-zealous marketing must surely be that sceptical customers (such as I hope you are, dear reader) will rule them out as frauds. They're not.

For the second example I'd like to thank reader Peter S., who drew my attention to a product that uses evaporative air cooling in place of conventional refrigeration. When the air is hot and dry, allowing it to absorb water will increase its relative humidity but reduce its temperature. This is because the water needs latent heat to become vapour, and taking that heat from the dry air reduces its temperature. It is a perfectly legitimate and effective method of reducing overheating but when a supplier claims a coefficient of performance of 20, they are bending the truth. The CoP is the ratio of cooling effect (thermal energy removed) to electrical energy put in: in evaporative cooling no thermal energy is actually removed, so it isn't fair to quote a CoP.

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24 MAY 2017


I think we may be making some headway against the claims made for voltage reduction (VR), thanks to greater awareness of the concept of an energy balance. Put simply, reduced energy input results in reduced output; so when you see a Youtube video "proving" that you get savings on a fan motor from reduced voltage at various speeds, the reason is simply that it is a free-running fan (keep your eyes open during the opening sequence) and they aren't mentioning its reduced air throughput at reduced power.

But now that vendors are being challenged over the energy balance, they have had to change their tune. They now say that motor-driven equipment "becomes more efficient" at lower voltage, enabling it to sustain its output with less input energy. Can this be true? Let's take the case of a motor delivering its maximum output of 7.5 kW. If it has an IE3 rating it would be working with an efficiency of about 90%, requiring 8.33 kW of input power. Now let's suppose that VR saves 10% on the input power (bigger savings are sometimes claimed), taking it from 8.33 to 7.5 kW. That would be the same as the output power. Bingo! A one-hundred-percent efficient motor.

In reality of course, maintaining output at lower voltage will necessitate a higher current (watts being volts times amps) and this will increase the losses in the motor, making it less rather than more efficient, and raising rather than lowering the input power required for the given output.

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3 MAY 2017


One of the basic rules of energy motivation and awareness is to avoid self-defeating behaviours. With our hotel energy-saving conference coming up I have been thinking about that industry in particular and found a good example: toast-making machines.

In some hotel breakfast rooms you'll find a toast-making machine running on the servery table. In contrast to a pop-up toaster, these things transport your bread between radiant elements on a little conveyor belt and they don't shut down between uses. They are typically rated at 2.5 kW making each one the equivalent of say 50,000 idle phone chargers. At about £300 a year tops the cost penalty compared with a pop-up toaster is not huge. The significant point is that staff and guests are getting a subliminal message that it doesn't matter if energy-using appliances are left running -- and that has much more costly consequences.

This is a classic 'own goal': irritating or alienating sympathisers while vindicating those who feel entitled to make free with resources they consider themselves to have paid for.

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24 APRIL 2017


An item sent in by your fellow reader Ian B. highlights just how useful testimonials can be. A brochure promoting on-peak electric wall heaters as an alternative to gas central heating includes this quote: "warmth keeps for longer in the home and you don’t have the strange smell like from pipes". The first assertion is an evident falsehood because heat retention depends on the building fabric, not the type of heater; and and as for smelly pipes... If you are relying for testimonials on people who can't tell a central heating radiator from a blocked toilet, you have a problem.

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3 APRIL 2017


A reader contacted me after hearing in the press that lab tests had cast serious doubts on the accuracy of electricity meters (including so-called ‘smart’ meters) when feeding low-energy lamps, variable-speed drives and other equipment that generates electromagnetic interference.

I contacted my friend Kris Szajdzicki who has been designing and manufacturing meters for 40 years to discover that he was already on the case, reviewing and investigating the reports. He eventually concluded: that such measurement errors do occur; that their magnitude depends upon the current-sensing technology used by the meter; but that the effect may be negligible in normal situations in the domestic market. However, his view is that there is still potential for 'gross error' in unfavourable circumstances, particularly in industrial or commercial installations - or where there is deliberate intent to fool the meter.

Kris has kindly let me publish his report and you can download it here


The UK government's Energy Technology List is an authoritative guide to products that save energy. It has to be rigorously policed because there is a tax advantage for certain energy users buying products that are on the ETL. Problem: how to get your bogus product onto the list? Here's a suggestion. Get a genuine, legitimate sister product included; then issue publicity material about it which segues seamlessly into a mention of the unlistable stuff.

You know who you are: thanks for the junk email that tipped me off to what you are doing.

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1 APRIL 2017


At £80 a pop in Harrods, according to last week's Economist, Svalbardi is the most expensive bottled water you can buy (it is made from Norwegian icebergs). We have long been used to brands like Perrier and Evian charging a premium for a commodity that most of us can get from the tap for almost nothing, so way back when the gas and electricity industries were privatised it must have irked energy suppliers that there was nothing they could do to differentiate their product from their competitors. "The same gas through the same pipes" is about as far from a unique selling proposition as it's possible to get; but all that is set to change in the electricity industry thanks to innovative UK startup Brain Power Limited.

BPL's marketing experts have taken inspiration from current trends such as voltage optimisation, variable frequency drives, and power quality monitors to create exciting new electricity supply options that they describe as "fit for the age of smart meters and artificial intelligence". Out is the bland sine-wave alternating current that has been the staple for public electricity supply in the UK for 70 years or more: "in" is a spectrum of waveforms ranging from the inexpensive square wave to the edgier sawtooth and, for the connoisseur, designer waveforms like 'ogive' which co-ordinates beautifully with Victorian architectural features. "The great thing about these non-sinusoidal waveforms is that they are really rich in higher harmonics", said a BPL spokesman.

There will be voltage options for every taste as well. 261 volts could appeal to musicians who will appreciate a voltage that equals the frequency of middle C. Nerds may go for 256 volts (because it is a "power" of 2). Initially available in single and three-phase supply only, BPL is rumoured to be releasing five and even thirteen-phase supplies after Brexit is complete, when customers will also be able to cast off the shackles of 50 cycles per second mains frequency.

Asked whether their catalogue will contain DC as well as AC options, BPL said that would be possible but only with batteries, which would be charged extra.

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20 MARCH 2017


EMSc, a supplier of voltage-reduction equipment, has had a complaint against it upheld by the Advertising Standards Authority in relation to an online advertisement for its ‘Powerstar’ range. The ASA said that EMSc should not claim a typical reduction regardless of the type of equipment fed by the mains supply. The advertisement was held to breach CAP Code rules 3.1 (misleading advertising) and 3.7, which states that when making such claims, marketers must hold documentary evidence “that consumers are likely to regard as objective and that are capable of objective substantiation”. The ASA considered that before making any efficiency savings claims for the equipment, Powerstar needed to hold evidence that supported the level of efficiency saving claimed “in the situations in which the equipment would be used”.

My view on voltage reduction is this: on the basis of a simple energy balance, reduced energy consumption will be achieved at the cost of reduced output. By the same token equipment with regulated or controlled output should use the same amount of input energy (in reality it may actually become less efficient thanks to increased resistive losses, and therefore draw MORE power at lower voltage; I show this in the case of an LED lamp in a video clip at http://youtube.com/vilnisvesma). It also annoys me that we rarely see a mention of the continuous standing loss incurred by the devices when energised.

Meanwhile the full ASA ruling, which must have implications for anyone promoting voltage "optimisation", can be seen at www.asa.org.uk: search their rulings for ‘EMSc’.

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25 JULY 2016


If you were considering whether voltage reduction will work for you, due diligence would entail surveying all your installed equipment and assigning it to the following classes: Only class 1 appliances will use less energy. Class 4 appliances risk using more unless people are currently preheating them for longer than necessary. Class 2(a) will be unaffected, but in the cases of 2(b) and 3, their energy losses may increase slightly. This is because to maintain a defined power output at lower voltage they will need the same input power but at a higher current -- giving more resistive loss.

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4 JULY 2016


If you are peddling dubious energy-saving products, independent verification is a threat but you can use it to your advantage. The smart snake-oil salesman mentions IPMVP (the best-known protocol) in his promotional literature, creating the impression that he has nothing to fear from independent scrutiny. Some go the extra mile and explain what adherence with IPMVP entails, making it look as disruptive and expensive as possible. This not only reinforces the false impression of openness, it further discourages buyers from actually doing it.

Of course, some customers may insist on using M&V, but that is not necessarily a problem. Randomness, experimental error, and flawed tests will occasionally throw up apparent successes which a verifier cannot find fault with. Conceal the adverse results, and publish the favourable ones -- citing the name of the verifier if he or she is certified.

With even a single verified "success", you can misrepresent the results as proving that the technology works in general, because hardly anybody knows that IPMVP is not valid for generic testing.

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30 JUNE 2016


Experts can be a nuisance, as we all know. There you are, minding your own business, promoting a bogus product in an on-line forum and up pops an expert challenging the science behind your claims. No problem: just dismiss them as “self-appointed” experts, and castigate them for having closed minds. Remind them that people used to think the Earth was flat.

On another occasion you might get a technical challenge in a conference or other live event with a skeptical audience. Again, no problem: just say that you are not a scientist yourself, and refer people to your case histories.

Your potential customers, fortunately, are themselves unlikely to be sufficiently confident of their own scientific knowledge to challenge you effectively. Just make sure they don't find out about the training I provide.

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1 APRIL 2016

In developments reminiscent of car-industry scandals, Endomagno Ltd has ordered a total product recall of its bolt-on fuel-treatment magnets after two serious incidents at customers' premises.

Such magnets are commonly claimed to improve consumption by aligning the gas molecules, and the incidents appear to involve the alignment effect being so strong that the gas has actually crystallised in the burner. Why this has started to happen now is not clear (the product literature points out that the Romans used lode-stones to improve the heat output of hypocausts) but my theory is that it relates to the introduction of new microcrystalline neodymium magnets in what the company describes as "a certain configuration". Chaos entanglement theory says that these may interact with quantum nanoparticles in the gas stream in unpredictable ways.

The product recall presents a significant logistical problem for Endomagno. Although the magnets are easy to attach using gaffer tape, they cannot be removed by the customer without invalidating the product's Korean patent. This means sending a technician to every site and as a market leader in magnetic fuel treatment they have nearly seven users.

Endomagno's marketing director, Frank Lee Beaugusse, told me that the company is urgently investigating two alternative technologies. The most promising is a unipolar magnet, which only has a north pole, but they are also testing more conventional magnets with east and west (rather than north and south) poles. Comparative evaluation and testing will be carried out by Laboratoires Garnier.

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14 MARCH 2016


There is a class of product that claims to save energy by enhancing the output of central heating radiators. Some are small fan units; but one, the Energy Squirrel, is just a stick-on metal plate (thanks to reader Nicola Terry for the tip-off there). Then of course we have the magic additives which improve heat transfer on the water side.

Many are sold on the basis that you will save energy because the room "will heat up faster". Could there be any truth in this? In principle, there might be. But savings would only arise you optimised the start time of the heating to take advantage of the shorter warm-up period. If you left the start time unchanged the result would actually be increased consumption with the room reaching its daytime control temperature prematurely.

However, from simulations I have run under typical conditions, you'd need to boost radiator output by half to yield a paltry 3% fuel saving. See the full article at enmanreg.org/radspeed.

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13 JANUARY 2015


For the keen energy waster faced with demands to have an energy audit, it is vital to employ an incompetent assessor -- one who can be expected to follow these principles:

1. Just turn up at site with a clipboard and start counting light fittings.

2. Never analyse historical data to identify anomalies that you could productively focus on during site visits.

3. Base your report on a previous one for a different client. A good trick is to use 'find and replace' to change the name in the body of the text, but overlook where it appears in headers and footers.

4. Always make at least ten recommendations, even if there is only one substantial worthwhile measure.

5. Always include recommendations for LED lighting and voltage reduction.

6. Over-estimate the savings expected from each recommendation.

7. Ignore any possibility of interactions between recommended measures.

8. Never obtain actual installation costs. Reverse-engineer them: take the annual savings and multiply by an assumed payback period.

Of course as a client, the keen energy waster has their own part to play in making the audit a futile exercise. Here are some tips:

1. Do not let anybody in the organization know about the audit visit.

2. Render all relevant data and drawings inaccessible.

3. When you receive the report, ignore it.

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15 OCOBER 2014


Transport in all its forms provides excellent opportunities to waste energy. Here are a few related to car, van and truck use:

1. Never arrange a telephone call or video conference if you can drive to a meeting instead. Driving long hours shows you are working hard.

2. Never share a car journey.

3. Make sure drivers have not got clear directions to their destinations, so that they get lost.

4. Use oversized goods vehicles whenever possible, and avoid consolidating loads to improve load factor.

5. Do not plan freight movements. For example if back-loads are available, it is better to send out empty vehicles to fetch them.

6. Never optimize multi-drop delivery routes.

7. Never give drivers training. Encourage them to accelerate hard, drive too fast in too low a gear, brake harshly, and idle their engines for long periods.

8. Fit the wrong kinds of tyres and run them at the wrong pressures.

9. Neglect maintenance of tracking and brakes: as well as wasting fuel you can spend extra on tyres and brake parts.

10. Do not monitor mileages, loadings or fuel purchases.

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7 AUGUST 2014


A big part of wasting energy is not knowing how much you use, when, where or for what. Most keen energy wasters rely on their energy suppliers not read their meters for them, but here are some top tips for those who want to be proactively bad: 1. Make it difficult to get access, for example by installing meters at height, or leaving the keys to the meter room with an obnoxious jobsworth.

2. Try to have meters installed in positions where you cannot see their dials.

3. Never have a reliable check-reading taken by somebody who knows what they are doing.

4. Do not create a meter schedule; if you have one, don't keep it up to date.

5. Do not try to find out what each meter serves.

6. If in doubt about units of measurement or scale multiplier factors, make whatever assumptions you like.

7. When a meter is swapped out, dispose of the old one without noting its final reading.

8. Do not train anybody to read meters.

9. Do not appoint stand-ins to cover for sickness or holiday absence.

10. Allow meter readers to be lax about when they take readings, and let them record the date they were supposed to take the readings rather than the actual date and time.

11. Allow meter readers to include or ignore decimal fractions as they feel inclined, if possible being inconsistent between visits to the same meter.

12. Rely on paper returns, and lose them.

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22 JULY 2014


The hot weather brings with it demands for air conditioning, and with that comes a whole raft of excellent ways for organizations to waste energy. Here are my top ten hot tips:

1. Don't argue when people ask for rooms to be cooled to 20C rather than the more sensible 27C. Every degree reduction in set-point adds 10-15% to the electricity used for cooling, and you may even hit the jackpot of some people turning on electric heaters as well.

2. Encourage people to leave the windows open with the air-conditioning on. This allows warm air in and expensively-cooled air out, more or less guaranteeing that the air conditioning will have to run flat out without reaching the desired internal temperature.

3. If it is not possible to leave the windows or doors open, minimise the recirculation of ventilation air.

4. Do not take advantage of lower overnight outdoor temperatures to pre-cool occupied spaces.

5. Encourage people to leave idle electrical items running, to increase the heat gains. Desk fans are an excellent example for those who can appreciate the irony: by creating air movement they make the occupants feel more comfortable, while continuously heating the air a little.

6. Believe your IT department and equipment suppliers when they say their kit needs to be housed at 16C (the idea that it might be designed to operate in tropical climates is ridiculous).

7. In computer rooms have the equipment racks all in the same space, so that their warm extract air mixes with the chilled air needed for intakes. Under no circumstances partition the space to separate cold and warm air.

8. If possible, house people and equipment racks in the same space as if they needed and/or could tolerate the same conditions.

9. Do not shield windows from direct sunlight.

10. Always use artificial cooling when increasing the ambient fresh air supply would do the job equally well.

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15 JULY 2014


When people ask me for advice on how to verify energy savings, it is usually because their analysis is not giving the results they expected. Often they have left it too late, developing a methodology after the event or even making it up as they go along. So if you are contemplating an energy-saving project the first plea I would make is this: agree a measurement and verification plan between the interested parties before the project starts. That way, everyone is forced to think about the calculation methodology and (just as importantly) focus on what data will be needed, who will collect it, and even how much uncertainty there is likely to be in the conclusions. It also pays to think about what non-routine changes might occur (patterns of occupation, extensions, demolitions, etc) and agree how those will be factored in if they occur.

Sometimes, fortunately, it is possible to rescue the verification of a project where the “shoot first, ask questions later” approach has been used. To achieve a resolution one needs two things: first a willingness on both sides to accept a retrospective definition of procedure; and secondly, at least some accurate prior consumption data. That consumption data can, however, be sparse, so the presence of a lot of estimates (a common situation) need not necessarily be a problem. The analysis in such circumstances is done using a technique called “back-casting”.

Recall that in a normal evaluation, accurate and complete pre-project baseline data are needed so as to establish the prior relationship between consumption and relevant independent driving factors (such as degree days, hours of darkness, production and so on). A formula is derived, typically using regression analysis, for predicting consumption from those driving factors. After the energy conservation measure (ECM) has been installed, that same baseline formula can be fed with driving-factor data and will yield an estimate of what consumption would have been in the absence of the ECM. The spread between this estimate and actual consumption is a measure of the ‘avoided’ energy consumption.

The back-casting method is different. It turns that logic on its head. Using post-ECM rather than pre-ECM measurements, a formula is developed which relates consumption to driving factors for the improved installation (rather than its original performance). Thus you can say that the analysis “baseline” period follows, rather than precedes, the ECM, which some people find odd. In this scenario, pre-ECM actual consumptions can be compared with what they would have been if the ECM had been active all along, and one would expect those actual consumptions to be higher than the model’s predictions (the opposite of the conventional approach where post-ECM consumptions turn out lower than the baseline model predicts).

Back-casting is no less valid as a method, but it enjoys one big advantage in that you only need two firm meter readings predating the ECM. They should be as far apart in time as possible, and you need to be able to retrieve driving-factor data spanning exactly the entire period between the meter readings, but if those conditions are met, your model formula can tell you what the expected consumption of the installation would have been over that entire period if the ECM had already been in place, and hence how much more was actually used in the absence of the ECM. This back-to-front approach is attractive because regular meter readings are generally easier to assure after the project than before.

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2 JULY 2014


People are your greatest asset in the battle against energy efficiency. Here are my top tips for disengaging your workforce:

1. Focus on trivial behaviours like leaving phone chargers plugged in.

2. Position climate change as a key consideration in order to maximise time-wasting and unproductive debate. Remember also that a message of fear will paralyse rather than stimulate action.

3. Over-promise with slogans like "together we can save the planet".

4. Give away branded mugs, coasters and other merchandise to enrage anyone bothered by waste of resources.

5. Do not canvass people for their opinions or ideas: remember the best instrument of communication is a megaphone.

6. If you do an opinion survey, use on-line techniques to be certain of reaching only those with computer access.

7. Use multiple-choice questions to be sure of missing responses you did not expect (obvious missing options also infuriate and alienate people).

8. Mount a high-profile launch event before you are ready with follow-on activities.

9. Appoint energy champions and leave them to sink or swim.

10. Be slow responding to staff suggestions.

11. If a suggestion does win an award, do not implement it.

12. Give individual cash awards: they can be wonderfully divisive if they are perceived as having gone to an undeserving winner.

13. If payouts are a share of savings, be ready to reduce the share for really successful ideas.

14. Don't forget everybody loves to be awarded a T-shirt with an energy-saving slogan on it.

15. Have a poster campaign.

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17 JUNE 2014


I am somewhat conscious of taking my life in my hands in this issue, but as so many readers have asked me what I think about voltage “optimisation” (or reduction, to use a more accurate term), let me answer the question with the following three guidelines, which apply to everything from heating and lighting to motive power:

1. If the equipment is regulated in any manner, don't expect voltage reduction to save energy.
2. If it is unregulated and you don’t mind reduced output, voltage reduction will save energy.
3. If it is a thermal application used on an intermittent cycle, voltage reduction will have a perverse effect, increasing energy consumption.

Editor's note: a more detailed explanation was given in Part 2 which has been omitted for lack of space here.

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10 June 2014


1. Use compressed air for dusting off overalls, sweeping the yard and other cleaning duties. This not only wastes energy but blows debris into people's eyes.

2. If you have individual applications that require a higher pressure, run the entire system to satisfy them rather than fitting local boosters.

3. Set overall system pressure as high as you can (check that the safety valves are lifting frequently). As a rule of thumb, every 2 psi increase in operating pressure requires an additional 1% energy.

4. For low-grade duties such as tank agitation, use clean dried compressed air at high pressure rather than fitting local blowers.

5. Locate air inlets in the hottest place possible - remember every 6C increase in temperature adds 1% to the electricity consumption.

6. Never clean your air filters and avoid fitting low-loss types.

7. Make sure you do not dry the air.

8. Allow all your compressors to run in parallel, sharing the load however small.

9. Do not shut the system down if the premises are closed at night; but if you do, empty the air receiver at the end of the day so that it needs to be repressurised in the morning.

10. Leave air-receiver drain cocks cracked open.

11. Bypass the air receiver so that the compressors have difficulty matching the load and need to start and stop frequently. This is a marvellously inefficient mode of operation, and abrupt swings in pressure will also help to maximise the number of leaking joints and fittings.

12. Maximise pressure drops in the distribution system by undersizing all pipework.

13. Ignore leaks: fixing one probably causes another to appear somewhere else. If you have a routine for tagging and repairing leaks, do not repair any that people find. As well as wasting energy this will discourage people from reporting air loss.

14. When specifying new equipment, give preference to models that continuously vent air. Use air tools if electric equivalents are just as good.

15. Look for opportunities to use compressed air inappropriately. Dusting off overalls may not waste enough; try using it for cooling motor bearings that are running hot, or to cool people working in hot locations.

16. Do not recover free heat from compressor exhausts if it is possible to use heat from a boiler system (or better still, electric heaters) instead.

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03 June 2014


1. If your light fittings are the type with translucent diffusers, fill them with dead flies.

2. Avoid replacing tungsten-filament light bulbs with compact fluorescent equivalents. Although it is now illegal to sell most general lighting service (GLS) filament lamps, one can still buy "rough service" equivalents which have the great advantage of being even less energy-efficient.

3. Keep your external lighting on 24 hours a day. This encourages a culture of not caring about leaving things running when idle, and will help waste many times more energy than is used in the lights alone.

4. Also keep your internal lights on continuously, not least because doing so will increase the demand for air conditioning.

5. Provide excessive light levels in working areas and try to ensure that corridors and stairwells are even brighter (this removes one of the vital cues that prompt people to turn lights off when they leave empty rooms).

6. Be careless when specifying automatic lighting controls. Choose the wrong sensor technology, so as to maximise nuisance switching. This has a dual benefit - it encourages people to override the control, and it also antagonises them so they won't cooperate with other energy-saving initiatives.

7. In shared workplaces, paint over any labels identifying which switch controls which zone.

8. Choose automatic lighting controls with remote control handsets that cannot be understood without training. Then lose the instructions and the remotes.

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20 May 2014


1. Set your frost-protection thermostat at too high a temperature.

2. Override your time control to run the plant continuously.

3. Set heating controls for maximum air temperature. The aim should be to make it so hot that occupants are forced to keep the doors and windows open, increasing the heat loss.

4. Alternatively, place a baked-potato oven under the space temperature sensor. This will hold the heating off and encourage people to bring in electric heaters.

5. If you have adaptive optimum-start control, set the timings as if it were a conventional time-switch (i.e. with start of occupancy at the same time you would previously have asked the plant to start up).

6. Also if you have adaptive optimum-start control, set a target temperature above the daytime control setpoint. The control will add more and more preheat every day because it never achieves the target temperature.

7. If you have air conditioning, set it to cool to a lower temperature than your heating, so that the two systems run simultaneously providing perfect comfort at infinite cost.

8. If you have humidity control, set it for the narrowest range conceivable. This will ensure you are nearly always either humidifying or dehumidifying.

9. Remove or jam the linkages on valve and damper actuators.

10. Do not commission your building energy management system; do not document the control philosophy or agreed settings; and as a backstop, lose the operating manuals.

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14 May 2014


1. When a motor fails, have it rewound, as this will reduce its efficiency.

2. If you need to replace a motor, use the cheapest and least efficient unit available (preferably oversized). Efficiency standards of new motors are being continuously improved, so you may need to shop on eBay.

3. Shift motors slightly on their mounting plates so that any drives and couplings are misaligned.

4. Ensure that drive-belts are slack. On multi-belt drives it can help to remove some belts. If possible, use the wrong kind of belt for the pulleys fitted.

5. Change pulley ratios to drive fans and pumps at higher speed: on centrifugal fans and pumps, a 20% speed increase adds over 70% to the load.

6. Neglect lubrication of bearings and gearboxes.

7. Allow equipment to run continuously, whether it is needed or not. This has the added advantage of accelerating wear and tear, and reducing your power factor.

8. When the driven equipment is decommissioned, at least leave its motor behind, energised and running.

9. In dirty environments, do not clean any debris off motor cooling air inlets. The extra resistance to air flow will increase mechanical losses in the motor and, as a bonus, accelerate its failure by causing it to overheat.

10. In situations where the mechanical output of a fixed-speed motor is controlled and regulated, run the motor below its rated voltage in order to increase the motor current and associated copper losses.

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9 May 2014


When you are looking for energy-saving opportunities, one of the most useful questions you can ask is: "how is that xxxx controlled?". Most energy-using systems benefit from good automatic control, whether it is temperatures or ventilation rates in a building, the output of a pump, or a lighting installation... You name it. Improving control is almost invariably a rapid-payback option, and uncovering incorrect control yields an instant win. This is one of the things I will be covering on 4 July in Manchester in my new workshop 'Finding energy-saving opportunities', and in Exeter on 5 June in the last of my 'Energy efficiency A to Z' courses. Details of all my planned events are at www.vesma.com/training, and remember to use the discount code EMR2012 to get your reader's discount.

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15 April 2014


One of my clients, who operates computer data centres, asked his monitoring and targeting software supplier to conduct some pilot analyses using daily data. Cusum analysis of one particular circuit, which was feeding computer-room air cooling (CRAC) units, threw up an interesting observation: energy performance had been toggling between good and bad on the first of every month. This fact had been masked by the weather and variations in the quantity of energy consumed in the equipment racks, but once revealed, it was traced to the fact that they were alternating two banks of CRACs on a monthly cycle.

In situations like this, it pays to change the regime so that preference is given to the more energy-efficient plant. This has the secondary advantage that the standby set will have more maintenance life left in it when the lead set fails.

Cusum analysis is very good at providing insights like this, which is why I give it prominence in my training courses on monitoring and targeting.


The other place one finds opportunities for instant savings is multi-boiler heating systems, where, too often, the firing sequence is deliberately rotated to give each boiler the lead and even out the wear. Apart from making no sense in terms of risk management (when one fails, all the survivors will be equally clapped-out) it also misses the opportunity to favour the unit with the highest combustion efficiency, and thereby consume less fuel for a given output of useful heat. Anyone unfamiliar with combustion efficiency and the opportunities that it offers can read up in the A to Z guide at www.vesma.com.

Combustion tuning is a good (and frequently-overlooked) opportunity for nearly all fuel users.

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1 APRIL 2014


“How green can you be?” is the message from major energy users Gulley Bull Ltd, who undertook a multi-faceted approach to saving fuel in their head office. They combined magnetic fuel conditioning, which offered a 20% saving, with two kinds of boiler water treatment. One, a simple cartridge containing special stones developed by a NASA scientist, changes a property of water to improve heat transfer by 25%. The other is a patented secret additive which prevents large steam bubbles forming in the boiler and also improves efficiency by 25%. Their building had solid walls, and was hard to insulate, but their energy manager’s researches uncovered a paint additive containing ceramic microspheres which, because they contain a vacuum, act as perfect insulators and promised a 30% saving on their heating costs just from redecorating the offices. Finally, they replaced their heating timeswitch with a control which claims to cuts fuel use by 16% by intermittently turning off the heating, saving fuel without sacrificing comfort: “an ingenious idea which took our total fuel savings to 116%” according to Gulley Bull spokeswoman April Fulstryk.

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24 March 2014


Super-thin thermal insulation is in my sights at the moment. There are two categories: (a) multi-layer foil and fibre; and (b) paints or paint additives. The insulating effect of multi-layer systems is basically equal to the same thickness of whatever insulating fibre they use, but there is some additional advantage where they are installed with an air gap either side, since they create an extra cavity which has a certain thermal resistance. Their reflective foil will impart additional thermal resistance by preventing radiation from the hot to the cold face of the cavity. But note, however, that after filling with ordinary fibre, the hot and cold surfaces of the cavity can no longer see each other, and heat transfer is solely by conduction. So BOTH techniques eliminate radiative transfer across the cavity and the foil therefore imparts no advantage.

Insulating paints meanwhile, even if composed of material with high thermal resistivity, will have totally negligible effect because the insulating layer is microscopically thin (under 0.3mm by my calculations, based on coverage data in the advertisements). Claims that their ingredients reflect heat are unsound because those so-say reflective materials are buried in the paint layer; to reflect heat the SURFACE of the paint would need to act like a mirror to infra-red radiation.

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28 January 2014


Stewart King from Aberdeenshire is among the readers who have alerted me to the rise of dubious claims for boiler water treatments in heating systems. In a new paper (www.vesma.com/downloads/op_treatment_savings.pdf) I show that the most you can expect from boiler cleaning (waterside and fireside combined) is probably about a 7% saving. I also should stress that ordinary good maintenance, including conventional descaling, is all you should need. If you have combustion test results of your own you can quantify the benefits of better maintenance using my Excel combustion calculator (www.vesma.com/tutorial/combust06.xls).

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18 April 2013


One of my readers has picked up on my advice about the fuel savings that can be had from independently testing the combustion efficiency achieved during boiler maintenance or between service visits. But he was worried that sampling of flue gases might come under the Gas Safe regulations (which they do not, by the way). He then quite reasonably contacted a training academy to see if they could provide instruction on flue-gas sampling, and they left him with the impression that there might be "health and safety issues" with the removal of sample-point plugs or caps.

As it happens the vast majority of flue sample points are just holes drilled in the exhaust flue pipe, and aren't closed anyway. As the exhaust gases are under slight suction at that point, any leakage will be into the flue rather than out into the boiler room. The exception would be where the sample point is after an induced-draft fan and in that case there will be a cap to prevent potentially-dangerous fumes escaping, the main danger being carbon monoxide, which normally should not be present.

The manufacturers of combustion analyzers promote them as being useable by a wide range of people, and their instruction manuals cover everything one needs to know about using them, including the necessity for replacing any cap or plug removed in the course of testing. If you are writing a method statement for people doing combustion tests, you might want to add a warning to avoid touching hot surfaces and a reminder that the business end of the probe will be hot after the test and shouldn't be touched or handled until it has cooled down. Sound like common sense? That's because it is, and this advice should not therefore be used in countries where people are legally required to be warned that coffee may be hot.

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1 April 2013


Got your shopping basket and cheque-book ready? Let’s build that library of energy-management systems standards!

We’ll start with ISO 50001 “Energy management systems. Requirements with guidance for use” at £174 (or bizzarely, £12 less for the laminated version), and to make sure we implement it correctly, fork out £212 for ISO 50004 “Energy management systems. Guidance for the implementation, maintenance and improvement of an energy management system”. To help us understand it all we might add PD CEN/CLC TR 16103 “Energy management and energy efficiency. Glossary of terms”. That’s only an extra £152 but we can probably pass up on ISO 9229 “Thermal insulation. Vocabulary” (£200) especially as the subject seems also to be covered in the cheaper ISO 9251 “Thermal insulation. Heat transfer. Conditions and properties of materials. Vocabulary” at just £90.

Stay with me... Next, we will almost certainly want to do some energy audits. ISO 50002:2014 ED1 “Energy audits. Requirements with guidance for use” would seem to cover the ground, and at £103 it’s £5 less than the European Standard EN 16247-1 “Energy audits. General requirements”. But – decisions, decisions - EN 16247 also boasts other sub-standards: Part 2 for buildings at £192; Part 3, processes at £146; and Part 4, transport at £104 (the prices differ because they charge per page). If we want to use benchmarking we could pick up a copy of EN 16231 “Energy efficiency benchmarking methodology” for only £152, and thinking about the qualifications of the people doing the work we should add PAS 51215 “Energy efficiency assessment. Competence of a lead energy assessor. Specification”, which at £70 seems quite good value until you read it.

Swap your shopping basket for a trolley now, because we’re going to think about measuring and verifying our savings. To set the scene, let’s fork out £212 on EN 16212 “Energy Efficiency and Savings Calculation, Top-down and Bottom-up Methods”. Please suppress the thought that probably crept into your mind on seeing the words “up” and “bottom” in the title of one of these worthy publications, especially as we will see them again when we splash out £146 on CWA 15693 “Saving lifetimes of energy efficiency improvement measures in bottom-up calculations”. Then to be on the safe side let's get ISO 50015 “Energy management systems. Measurement and verification of energy performance of organizations. General principles and guidance” at £152, plus ISO 50006 “Energy management systems. Measuring energy performance using energy baselines and energy performance indicators. General principles and guidance” (£174). Nearly done... To make sure that our efforts to comply with all this stuff are up to scratch, let’s round off with £146 for ISO 50003 “Energy management systems. Requirements for bodies providing audit and certification of energy management systems”.

All in all, the bill could be over £2,000. There is no truth in the rumour that the International Standards Organisation, British Standards, and the Comité Européen de Normalisation are contemplating a joint venture to be called “ISO, BS and CEN Enterprises” or ISOBSCENE.

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12 March 2013


From time to time I am asked for 20-year average degree-day figures, but from past years. A request like this always rings slight alarm bells because it is a bit like asking for a copy of a weather forecast that was broadcast a few months ago. Twenty-year averages are only supposed to be used for estimating future consumption, so only the most recent set is of any value.

It turns out that some users are using the averages for weather adjustment. They are taking the fuel used for heating in a given month, dividing by actual degree days (so far, so good) and then multiplying by the 20-year average degree days for that month. This gives them actual consumption adjusted to average weather. This is where an error creeps in. If they use a revised average each year, the result will change. Suppose the climate is getting milder: their adjusted fuel consumption will turn out less than it should, flattering the trend. To make the comparison fair one should use the same "average" degree-day number every year.

Just choosing a set of twenty-year average figures and sticking with them in perpetuity is one solution, but it isn't the best. It cures distortion of trends but it still leaves one unable to benchmark one building against another. To do that, the buildings' fuel consumptions should be normalised against a common fixed reference standard weather year, such as that shown at www.vesma.com/ddd/std-year.htm

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8 February 2013


The National Library of Scotland has achieved energy savings of 34% over two years. By careful experimentation with temperature and relative humidity settings, they found they could safely operate outside the limits stipulated in BS5454, whose requirements they had previously been following rigidly. According to NLS's Linda MacMillan, speaking at the Scottish Energy and Environment Conference on Tuesday, their consumption is down becasue with floating setpoints their dehumidification load is now "almost at nil" -- with no risk to their stock.

It seems that there had been no scientific basis to the limits for temperature and RH cited in BS5454, and it was probably a case of the air-conditioning industry dominating discussion in the drafting process.

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24 January 2013


Looking at how somebody had set the timing on a school heating system I noticed that their weekday schedule ran from 06:00 to 17:00. Normally this might be reasonable, but only if they were using a fixed-time control. In fact the control was an "optimiser", a timeswitch that automatically delays the startup time to prevent the building getting up to temperature earlier than necessary. Optimisers adapt to the characteristics of the systems they control, aiming to achieve a chosen target temperature at a specified time. Therein lay the users' error: their school was going to be snug and cosy at six o'clock every morning (at least two hours prematurely). An optimiser schedule must be set for the start of occupancy, not the plant startup time.

They had also set the optimiser target temperature at 21 degrees C. Two things wrong with that. The main thing is the risk that this target temperature will not be reached (because the normal thermostatic controls will prevent it getting there). If that happens, the optimiser will always think it has failed to allow enough preheat time, and will progressively start the plant earlier and earlier every day. The other bijou problemette with 21 C is that it is illegal. The Fuel and Electricity (Heating) (Control) (Amendment) Order 1980 generally prohibits artificial heating above 19 degrees.

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2 October 2012


Pretty well everyone has combustion apparatus (typically the burners on heating boilers) among the things they deal with as an energy manager. Management of combustion efficiency is a universal and often-neglected opportunity to save energy for next to nothing. Here's how.

A proportion of the heat released during combustion inevitably escapes up the chimney (a) because the exhaust gases are hot, and they contain either (b) any excess air that wasn't needed for combustion or (c) unburned fuel if insufficient air was supplied. Ensuring that burners are properly tuned during routine maintenance will ensure that the proportion of energy lost in this manner is minimised. It may only save a few percent, but the point is that the saving is free if you manage your maintenance contractor proactively: good burner tuning is just part of diligent maintenance.

Interesting, percentage losses in flue gases can be inferred using measurements of their oxygen and carbon monoxide levels, together with their temperature relative to the air in the boiler room. The apparatus to do this is perfectly affordable for many energy users, enabling them to keep an eye out for loss of efficiency.

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18 September 2012


One of the first steps in any energy motivation and awareness campaign is to establish what people in the organisation currently think about the subject. A questionnaire is one possible method, but designing an effective one is tricky. They quickly become bloated, and think about this: how often have you filled in a multiple-choice questionnaire and been frustrated because the answer you wanted to give was not one of the options?

I would like to suggest two guiding principles. Firstly limit yourself to four questions; and secondly make them open-ended. The four that I usually use are:

  1. Do you think there is significant energy waste at work?
  2. If so, whose job should it be to deal with it?
  3. If you think it is important for the organisation to save energy, why?
  4. What other aspects of your work are as important, or more important?
The answers to these questions are all you should need as a foundation. You may find the responses rather surprising, but that is good because it shows that your own preconceptions were wrong.

If you work for a large organisation you probably dread having to read and analyse all the free-text responses. But there is a way around that problem: invite people to discuss the questions with their friends at work and submit a group view. That not only reduces your workload, but also raises the profile of the subject, which is after all what you are trying to do.

The next step would be to publish the conclusions promptly in a half-page summary, focussing on those areas of consensus which are helpful or neutral to your campaign. This feedback serves several purposes, one of which is that it subtly helps to align everyone's attitudes through the phenomenon called 'social proof', the unconscious tendency to behave like other people whom we regard as similar to us. And of course the effect works on everyone who hears the feedback, not just those who responded to the survey.

But don't do the survey in isolation: have your next few steps planned out. Be ready, for example, to have people suddenly start making more suggestions. A positive groundswell of opinion will be wasted if your campaign cannot respond smoothly.

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16 August 2012


1. Make maximum use of decoration. Bright colours, gradient fills, 3-D effects, borders and boxes (preferably with shadows) are essential because your readers have a mental age of six and are easily bored by information.

2. Put your logo prominently on the top left-hand corner of the screen, because that is prime real estate. It is where the user’s eyes will usually land first, and your brand identity is surely the most important piece of information on the screen.

3. Pack in as much data as you can. Empty space on a dashboard is a clear signal that you have not been working very, very hard.

4. Pie charts are the perfect choice for presenting comparative data because (a) there is a limit to the number of items that they can portray, and (b) the human eye finds it difficult to judge the relative areas of the segments (use 3-D pie charts to make it even harder). Labelling the segments with text around the perimeter, connected by leader lines, is an excellent way to make the graphic shrink to an unusable size, but you may prefer to use a colour-coded key which will significantly slow down interpretation of the chart — and ideally render it ambiguous or even unusable for anyone with impaired colour vision.

5. Dial gauges are a very good way to use more space than necessary to report a single numerical value. Using a dial proves that you are clever and understand the dashboard metaphor. If users need to compare a selection of different values, an array of ‘rev counter’ gauges is an attractive way to prevent them doing so easily.

6. Make liberal use of vertical text for chart labels, to make users crick their necks (having a mix of upward and downward text directions really shows your disregard for their comfort). Text must be in a mixture of large and tiny fonts: large to use up space, small to make things difficult to read, and the mixture to make the presentation uglier in case you have otherwise failed to make it garish enough.

7. When reporting two or more associated variables, stacked column graphs are an excellent way to conceal trends and comparative values. If possible put the values with most variability at the bottom of the stack, to ensure that the values of the second and subsequent tranches are as difficult as possible to follow.

8. If you are displaying a history of monthly consumption values, use a column-chart format overlaying one year on another (all Januaries together, and so on) to prevent the long-term trend being visible and to hide what happens at the turn of the year. With the right choice of column colours, moreover, you can arbitrarily emphasise one year in particular. Never use a simple line chart to portray the history of a measured value, because it makes it too easy to spot trends.

9. Always report numerical values to as many decimal places as possible.

10. A table should always be presented as a grid with lines separating the rows and columns, because the recipients, who are stupid, will not be able to read it otherwise. They may not even realise that it is a table. Redundant separators are also an excellent way to force the use of unreadbly-small type.

11. Be sure to restart all reports and charts at the beginning of the year and discard any earlier data. It is vital to avoid moving averages, rolling totals and other representations that make it easy to perceive longer-term trends. Instead, be sure to reset all averages and cumulative totals to zero each year (or on a monthly, weekly or daily basis if it is important to disrupt the continuity of shorter-term reports).

12. Avoid giving any indication of context or significance, such as whether a reported value is within acceptable limits, on a trend in a particular direction, subject to high variability, and so on. Under no circumstances should you compare actual with expected values, much less prioritise any deviations or hide instances that are not significant. Your invariable aim, when reporting a numerical value, should be to have the user say: “so what?”.

... Joking aside, if you are interested in how to do the job well, I heartily recommend the textbook 'Information Dashboard Design' by Stephen Few, who is a strong advocate of clean, lean and uncluttered displays and offers a wealth of design tips.

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