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SECR in a nutshell

“Streamlined energy and carbon reporting” (SECR) is the term commonly used to describe the regime introduced with the Companies (Directors’ Report) and Limited Liability Partnerships (Energy and Carbon Report) Regulations 2018, Statutory Instrument 1155. This is not a self-contained set of regulations like ESOS; instead it consists of nothing but dozens of amendments to existing company reporting law. In short, undertakings covered by SECR simply need to collate annual total energy and emissions data and give them to their company secretary or accountant for inclusion in the annual report that they already have to prepare.

As this is an extension of financial reporting, compliance will be policed by the Financial Reporting Council, and not, as one might have thought, by the Environment Agency. The good news is that in terms of accuracy and completeness, your SECR reports need only be free of material misstatements, and according to the Government’s published guidance it is fine for a company to omit 2-5% of its energy or emissions if it considers them not to be material in the grand scheme of things.

Who is affected?

SECR applies to all quoted companies, and to unquoted companies and limited liability partnerships (LLP) which meet two of the following three criteria:

  1. At least 250 employees;
  2. £36 million annual turnover or more
  3. Balance sheet of £18 million or more

This is not quite the same as the ESOS regulations, in which an undertaking would be obliged to participate if it met criterion (a) alone.

Undertakings which consumed less than 40,000 kWh in the year being reported do not have to report their actual figures but must still state that they fell below that threshold.

It is fine for a company to omit 2-5% of its energy or emissions if it considers them not to be material

Group reports should include the figures for all subsidiaries apart from those that would be exempt. Under these circumstances a subsidiary need not report its own figures although, of course, it will still need to collate the data for group use.

What must be reported?

The requirement covers energy use and greenhouse gas emissions arising from all use of electricity, gas, and transport fuels. Incidentally the definition of “gas” is not limited to natural gas, but refers to any gaseous fuel so it even includes hydrogen. The inclusion of electricity means that SECR differs from emissions reporting. Somewhat bizarrely liquid and solid fuels do not have to be accounted for, unlike in CRC (which SECR supposedly replaces) ESOS and EUETS. Bought-in heat, steam and cooling are included but not compressed air.

Quoted companies must report global figures, but LLPs and unquoted companies only have to declare UK consumption and emissions.

In the main, therefore, any undertaking that already keeps even very basic monthly fuel and electricity consumption records for its fixed assets will have no trouble collating the necessary energy data. Transport fuel, of course, is a different issue. As many an ESOS participant has found, transport fuel data are disproportionately hard to collect relative to its importance in the mix. Luckily, if you can reasonably assert that your transport energy and emissions are not material to the overall picture, you can just leave them out.

My advice would therefore be to look first at transport fuels, decide whether they are material, and if so put resources into capturing the data or estimating the figures.

SECR requires emissions to be reported as well as energy consumptions. The necessary factors are published by the government and undertakings would be well advised to set up a methodical procedure for carrying out the calculations, because they must include details of their methodology alongside the data that they report.

Undertakings must report intensity metrics, of which an example would be kWh per unit of saleable product output. The idea is that stakeholders will be able to see, once a year, what progress the company is making in energy efficiency. This is actually a somewhat naïve and fanciful aim, given all the ways that such simple ratios can be distorted by external factors nothing to do with energy performance. Even more implausible is the idea of making ‘benchmarking’ comparisons between enterprises, but that is the government’s stated objective.

Companies are entitled not to report intensity metrics if, in their opinion, it would be prejudicial to their interests to do so. For example it might entail disclosing sensitive information about their sales volume. One option is to quote a metric based on financial turnover (which is already disclosed anyway). This may not be meaningful, but then neither is anything else they might report.

Finally, annual reports must now include descriptions of the principal measures taken to improve energy efficiency during the year in question, if there were any.

What is the compliance deadline?

Energy, emissions, intensity metrics and associated methodologies must be stated in annual reports covering accounting years starting in April 2019 or later. So the first wave will be reports for the year ending March 2020 and the last will be those with years ending in February 2021. This at least leaves plenty of time to get data collection in order. Actual report submission deadlines fall six months later for public companies (nine for private companies).


See links to SECR resources

Monitoring electrically heated and cooled buildings

WHEN you use metered fuel  to heat a building (or indeed if you use the building’s electricity supply, but have no air-conditioning) it is straightforward to monitor heating performance critically because you can relate energy consumption to the weather expressed as degree days.

Things get difficult if you use electricity for both heating and cooling and everything shares a meter, as would be the case if you use reversible heat pumps (air-source or otherwise). Because the seasonal variations in demand for heating and cooling complement each other (one being high when the other is low), you may encounter cases where the sum of the two appears almost constant every week. Such was the case on this 800-m2 office building:

Figure 1: apparent low sensitivity to weather

 

Without going into detail, this relationship implied a heating capacity of little over 1 kW, which is obvious nonsense as there was no other source of heat. The picture had to be caused by overlapping and complementary seasonal demands for heating and cooling, which is illustrated conceptually in Figure 2:

Figure 2: total consumption is the sum of heating and cooling demands

 

The challenge was how to discover the gradients of the hidden heating and cooling lines. The answer in this case lay in the fact that we had sufficient information to estimate the building’s heat rate, which is the net heat flow from the building in watts per unit inside-outside temperature difference (W/K). The heat rate depends on the thermal conductivity of the building envelope and the rate at which outside air enters. There is a formula for the heat rate Q:

Q = Σ(UA) + NV/3

Where U and A are the U-values and superficial areas of each building element (roof, wall, window, etc), V is the volume of the building and N is the number of air changes per hour. Figure 3 shows the spreadsheet in which Q was calculated for the building in question (an on-line tool to do this job is available at vesma.com):

Figure 3: calculation of heat rate

In this case the building measurements were taken from drawings, the U-values were found on the building’s Energy Performance Certificate (EPC), and the figure of 0.5 air changes per hour is just a guess.

The resulting heat rate of 955.5 W/K equates to 955.5 x 24 / 1000  = 22.9 kWh per degree day. This is heat loss from the building but it uses a heat pump and will therefore require less input electricity by a factor of, in this case, 3.77 (that being the coefficient of performance cited on its EPC).  So the input energy required for heating this building is 22.9 / 3.77 = 6.1 kWh per degree day. This is the gradient of the unknown heating characteristic, the upper dotted line in Figure 2.

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To work out the sensitivity to cooling demand we use a little trick. We take the actual consumption history and deduct an allowance for heating load which, in each week, will be 6.1 times the number of heating degree days (remember we just worked out the building needed 6.1 kWh per degree day for heating). This non-heating electricity demand can now be analysed against cooling degree days and this was the result in this case:

Figure 4: variation of non-heating electricity with cooling degree days

 

The gradient of this line is 3.5 kWh per (cooling) degree day. It is of similar order to the 6.1 kWh per degree day for heating, which is to be expected; the building’s heat loss and gain rates per degree difference are likely to be similar. As importantly, we now have an intercept on the vertical axis (a shade over 1,200 kWh per week) which represents the non-weather-related demand. Taking Figure 1 at face value we would have erroneously put the fixed consumption at around 1,500 kWh per week.

Also significant is the fact that Figure 4 was plotted against cooling degree days to a base of only 5°C. That was the only way to get a rational straight line and it means there is a finite amount of cooling going on at outside temperatures down to that value. I had been assured that cooling was only enabled “when the weather got hot”. But plotting demand against cooling degree days to, say, 15.5°C (a common default for summer-only use) gave the result shown in Figure 5:

Figure 5: non-heating electricity demand against cooling degree days to a base of 15.5C

 

This is not as good a correlation as Figure 4 and my conclusion in this case was that when the outside temperature is between 5 and 12°C, this building is likely to have some rooms heating and some cooling.

Carbon emissions – a case of rubbish data and wrong assumptions

The UK Government provides tables for greenhouse gas emissions including generic figures for road vehicles. For example a rigid diesel goods vehicle of 7.5 to 17 tonnes has an indicative figure of 0.601 kg CO2e per km. You need to apply such generic figures with caution, though. I saw a report from a local council that used that particular number to back-calculate emissions from its refuse collection trucks. Leaving aside the fact that many of their vehicles are 26 tonners, they spend much of their time accelerating, braking to a halt, idling and running hydraulic accessories, with the result that one would expect them to do no better than about 4 mpg with emissions more like 1.8 kg CO2e per km, three times the council’s assumed value.

For the council in question that is not a trivial error. Even on their optimistic analysis domestic waste collection represents 33% of their total emissions. Properly calculated (ideally from actual fuel purchases) they will turn out to be more than all their other emissions taken together.

Further reading

Training

For sustainability professionals to make a real practical difference to carbon emissions they need a broad appreciation of technical energy-saving opportunities. To help them understand the potential more clearly I run a one-day course called ‘Energy Efficiency A to Z‘. Details of this can be found at http://vesma.com/training

 

Network operator promoting voltage reduction

Regular readers of my newsletter will know that I take a pretty dim view of people who try to sell voltage reduction — or what they often misleadingly call “optimisation” –as an energy-saving technique (see footnote for more details)

One of my readers was therefore surprised to read an Observer article on the Guardian web site in which a network operator, Electricity North West (ENWL), was touting the benefits of voltage reduction as a way to cut customers’ bills. The article correctly stated that customers’ kettles would take longer to boil because of reduced power output, but suggested wrongly that their consumption would go down as a result. In fact, it will slightly increase because the longer heat-up time increases the duration of heat loss from the kettle, and that extra heat loss needs to be made up from extra electrical energy input (the amount of heat put into the water is the same, so no effect on consumption there). This same perverse result – higher consumption at lower voltage – will apply to all thermal appliances operated on intermittent cycles.

I looked at some research that ENWL had commissioned on parts of their network, which had shown that a 1% drop in substation voltage had resulted in a 1.3% drop in power to connected customers. That is plausible but not the whole story. It’s true that for some unregulated appliances like incandescent lamps and toilet extract fans, reduced power will have resulted in reduced output (which nobody noticed) and hence lower energy consumption. But for thermostatically-controlled appliances like space heaters, ovens and immersion heaters, lower power will be compensated for by increased run times and there will be no saving. ENWL’s public-relations people have confused power (kW) with energy (kWh).

In reality ENWL probably have a different agenda and I think that the research behind their conclusions is part of a lobbying effort to get the legal limits on voltage relaxed, which will make it life easier for them in a world of distributed generation. When customers’ solar panels are generating at their peak, they tend to push the voltage up on the low-voltage network; and conversely being able to drop the voltage maximises how much solar power can be absorbed. Pretending that lowered voltage saves money is part of their pitch.

Footnote: 

Different types of electrical equipment will respond in different ways to reduced supply voltages. In short:

1. If the equipment is regulated in any manner, either in terms of its output or internally to maintain set voltages for electronics, 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.

Gross and net calorific value

“Efficiency” in our business means the ratio of the useful output energy to total input energy. Unfortunately, when evaluating combustion performance, there are two versions of the input energy because any hydrocarbon fuel has both “gross” and “net” calorific values (GCV and NCV).

To understand the difference, you have to appreciate that the products of combustion include water vapour, and that it takes energy (latent heat) to vaporise water whether it happens in a kettle or as part of the combustion process. In a condensing boiler you get that latent heat back. A fuel’s GCV counts all its chemical energy but its NCV disregards that fraction (10% in the case of natural gas) that will be absorbed as latent heat. So when you calculate efficiency on the basis of NCV you get a higher value than if you had used GCV, to the extent that you see condensing boilers advertised as having over 100% efficiency. That is actually true on an NCV basis, but only because there’s energy in the fuel that NCV ignores.

Why does this matter? Because when you look at a combustion test report from a maintenance contractor it may well be on an NCV basis, which somewhat flatters the performance. I prefer to use the GCV basis. Some combustion analysers also make an allowance for boiler standing losses in an effort to give a supposedly more realistic overall efficiency figure, but that just clouds the issue in my mind.

If you want to be sure you are getting results (a) in GCV terms and (b) without deductions for standing losses, you can take the raw measurements from a boiler test and feed them into this on-line calculator, which incidentally lets you try changing the input assumptions for a side-by-side estimate of the savings that would result.

ISO50001 Q&A

One of my newsletter readers, A.M., wrote from New Zealand with a series of questions about ISO50001, the management-systems standard for energy management. He has just started to get to grips with the 2018 edition. Here are his questions and my answers:

A.M.: How we distinguish between boundaries and scope? if boundary is simply the physical borders for the system (e.g. the office buildings), what is scope then? and if scope is for example “transportation” and etc., why in SEU [significant energy use] we say “Transportation” could be an SEU as a process?

V.V.: “Scope” means the range of activities covered. For example “manufacturing processes” or “heating, ventilation and air conditioning” or, as you say “transportation”. Within transportation you might have, for example, “freight” as an SEU, but equally you could declare all transport as significant. There is no paradox here.

A.M.: In the new edition, the top management shall take all the responsibilities that the representative had in the last edition. This sounds impossible to delegate all the tasks to the top management. How do we cope with this?

V.V.: If you are responsible for a task you can delegate it but still keep responsibility, i.e., it is your fault if the people you delegated it to fail to carry it out properly. Managers are accountable for the actions of subordinates.

A.M.: In section 4.3, page 8, after b) we have a statement “The organization shall not exclude an energy type within the scope and boundaries” I do not understand the idea! why we are not allowed to do so?

V.V.: The requirement seems logical to me. For one example: if you have transport as your scope and you have plug-in hybrid vehicles, it is reasonable to insist that you cannot exclude any electricity used by them. Another example: if you had an oil-fired boiler and replaced it with a wood-fired one, it would evidently be wrong to exclude the wood fuel from consideration.

A.M.: If a new opportunity would become replacing diesel boiler with wood pellet, it means we are changing the energy types which does not necessarily reduce the energy costs. Can we call it action plans?

V.V.: ISO50001 is about managing energy performance, not costs or carbon. If substituting a different fuel improves the energy performance, it will contribute to your aims and objectives, so it would make sense to classify the work as an action plan.

A.M.: I understand that for each energy type, we identify SEU(s) and for each SEU, we list the action plans. What if one action plan reduces diesel and increases electricity? Do we still keep it as an action plan for diesel?

V.V.: What matters is the overall energy performance. If the amount of electricity consumption that you add exceeds the amount of diesel energy saved, your energy performance would be worse after the project and it would therefore make no sense to include the project in an action plan within your EnMS. If the project is going to improve energy performance, you could declare it as part of an action plan.

LED versus metal halide lamps

Clare C., a regular reader of my energy-management bulletins, was perplexed when she started researching the cost advantages of LEDs as replacement for metal halide (MH) high-bay fittings. She discovered that MH lamps have luminous efficacies very similar to LEDs with both, broadly speaking, yielding about 100 lumens per watt. Certainly she wasn’t going to get the 50% saving she was after, and she asked my opinion.

There are a couple of factors that would tip the balance in favour of LEDs. Firstly, she needed to account for the fact that unlike LEDs, MH lamps need control gear which would add some parasitic load (say 20 watts on a 400-watt lamp).  Secondly, LEDs are more directional and can deliver all their output more effectively to the working space; MH lamps are omnidirectional and need reflectors which may lose some of the light output. So in terms of useful light output per circuit watt, a well-specified and correctly-installed LED fitting may have a moderate advantage.

But the big gain is in controllability. MH lamps have a warm-up time measured in minutes and a ‘restrike’ time (after turning off) which is longer still, to allow them to cool before being turned on again.  This is common to all high-intensity discharge (HID) lamps. It does not matter how long the delay is; it discourages the use of automatic control so  HID lamps are often turned on well before they are needed, and then stay on for the duration. LEDs by contrast can be turned off at will and as soon as they are needed again, they come on. This is where Clare will might get her 50% saving.

High-intensity discharge lamps in a sports hall – a good candidate for LEDs because of erratic occupancy

Ultra-rapid charging

StoreDot and BP present world-first full charge of an electric vehicle in five minutes” runs the headline on this news item from BP which actually talks about an electric scooter. The Storedot website is a bit more gung-ho about their new battery technology, which they think would enable a 5-minute full recharge of an electric car with 300 mile range. Really?

Quick sense check: for a 300 mile range you’d be talking probably about a 100-kWh battery for which a 5-minute full recharge would demand 1.2 megawatts of charging capacity. That’s going to be some meaty charger. Moreover, even upping the charger voltage to 1,000 volts you’ll be drawing 1,200 amps, so I reckon the charger cables are going to need a pair of conductors of (say) 4 square centimetres cross section. And cars would need to be engineered with DC charging circuits to match …

I put these points to StoreDot and they pointed me to Chargepoint’s website which talks about “up to 500 kW” Express Plus charging using the CCS Type 2 connector, although as far as I know CCS2 goes nowhere near that rating and when those kinds of powers are achieved they are going to need thousand-volt water-cooled charging cables with thermal sensing on the plug because of the risk of overheated contacts.

Our next course on transport energy and carbon is on 17 October: click here for details

Back to the scooter that BP had seen recharged in 5 minutes. The  model in question has two 48V 31.9 Ah batteries (so about 3.1 kWh) which to recharge in 5 minutes would require a 37 kW charger – plausible in a non-domestic setting. I imagine the demonstration to BP involved removing the batteries to recharge them because obviously the scooter’s onboard electrics would not be designed to handle a charging current of 800 amps.

My colleague Daniel did some digging and unearthed this priceless video from StoreDot in 2014, purporting to show a smartphone being completely recharged in 30 seconds using battery technology that would be released in 2016 (I’m still waiting…). The sceptical comments are worth reading — especially the ones about fake phone screens, and indeed the ones about exploding phones — but you can’t help but notice in the video itself they are actually “charging” a huge battery glued to the back of the phone. So a big dose of scepticism is in order, I think, and if the link to the video no longer works you can guess why.

More credible is the news this April about battery developments using vanadium disulfide cathodes stabilised with a microscopic layer of titanium disulphide: this promises faster charging but they are careful not to say how much faster.

Water treatment

Scale build-up from hard water is often cited as a cause of energy waste in hot-water systems (I am talking here about ‘domestic hot water’ supply, not closed loops within central heating systems). Actually though, contrary to claims for some water treatment devices, it is not necessarily the case that energy waste will be significant. Indeed with an electric immersion heater on a 24-hour service, all the supplied energy still gets into the water; there is no loss. Of course the rate at which the water temperature recovers will be reduced, and the heating element will fail prematurely, but those are service and reliability issues not energy waste.

The story is a little different on intermittent hot water storage of any kind. Here, because scaling will retard temperature recovery, users may extend preheat times and that will result in a marginal increase in standing heat loss. If the heat supply is from a primary (boiler-fed) water loop, the primary return temperature will be higher because scale impedes heat transfer, and this also will increase standing losses although in reality not to a significant extent in the grand scheme of things. If hot-water recovery times deteriorate markedly, users may of course dispense with time control altogether and in those circumstances avoidable standing heat loss might become significant if thermal insulation is poor.

Preventing scale build-up

Simplifying the story somewhat, the main constituent of scale is calcium carbonate, which starts to form above about 35°C through breakdown of the more soluble calcium hydrogen carbonate that is present to varying degrees in the public water supply, with  ‘hard’ water containing higher concentrations of it. Calcium carbonate crystals of the normal ‘calcite’ form stick to surfaces and each other, and that is what constitutes limescale.

One way to deal with this is softening which (in its strict sense) involves a chemical process to turn calcium carbonate into sodium carbonate which does not precipitate as crystals but stays in solution. The process is costly in terms of chemicals; a waste product, calcium chloride, needs to be flushed away periodically; and the softened water is unsuitable for drinking and cooking because of its high sodium content.

The alternative to chemical treatment is physical conditioning. Various proprietary methods are available. Some involve electric or magnetic fields which are supposed to affect the calcite crystals in some way (for example giving them an electric charge so that they repel each other, or in some other manner inhibiting their tendency to agglomerate).

Another class of conditioner is electrolytic. Electrolytic devices release of minute quantities of zinc or iron into the water, which change the calcium carbonate to its ‘aragonite’ form which, unlike calcite don’t stick together, so they stay in suspension and do not contribute to scale formation.

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With the exception of electrolytic devices, there is no scientific explanation of how or why most  of these physical conditioners work, and there are no accepted tests of efficacy. There is only anecdotal evidence, but if it works, it works.

The one method of physical condition which is definitely effective (and I can vouch for it personally) is polysilicate-polyphosphate dosing. This has a dual action. It modifies the carbonate crystals to stop them sticking to each other, and it coats the inner surfaces of pipework and appliances to inhibit scale formation.

For anybody wanting further references, this note from WRc commissioned by Southern Water is what I currently regard as the most authoritative advice on the subject of water treatment techniques.

The value of a tree

We all know that trees are good and absorb carbon dioxide. But how good are they? Let’s work it out…

Trees absorb carbon dioxide at different rates depending upon their age, species and other factors but as a rough order of magnitude you can say the figure for a typical established tree is 10 kg per year. The carbon dioxide emissions associated with energy use are 0.2 kg per kWh for natural gas and (in the UK in 2018, including transmission losses) an average of 0.3 kg per kWh for electricity.

So 50.0 kWh of gas or about 33.3 kWh of electricity each generate the 10 kg of CO2 that a single tree can absorb in a year. Take that figure for electricity. As a year is 8760 hours, 33.3 kWh equates to a continuous load of only 3.8W. So one entire tree compensates for one broadband router, a TV on standby, or a couple of electric toothbrushes or cordless phones (roughly).

And as for gas consumption: remember pilot lights? The little flame that burns continuously to ignite the main gas burner? If you had pilot flame with a rating of 100 watts, in the course of a year it would use 876 kWh and require no fewer than 17 trees to offset its CO2 emissions..

Are the assumptions correct?

The first time I published this piece in the Energy Management Register bulletin my estimate of CO2 takeup rates was challenged. Fair enough: I plucked it from stuff I had found on the Web knowing that it might be out by an order of magnitude. So let’s do a sense check.

The chemical composition of wood is 50% carbon (on a dry-matter basis) and all that carbon came from CO2 in the air. So 1 kg of dry woody matter contains 0.5 kg of carbon, which in turn was derived from 0.5 x 44/12 = 1.833 kg CO2 . Thus if we know the growth rate of a tree in dry mass per year, we can multiply that by 1.833 to estimate its CO2 takeup. Fortunately a 2014 article in ‘Nature’  has the growth figures we need. Although there is wide variability in the results, for European species with trunk diameters of 10 cm the typical growth in above-ground dry mass is 1.6 kg per year, equating to a CO2 takeup of only 2.9 kg per year (although this rises to 18 and 58 kg per year for diameters of 40 and 100 cm). So newly-planted trees (which is what we are talking about) are going to fall well short of my 10 kg/year estimate, and it will be years before they reach a size where their offsetting contribution reaches even modest levels.

I like trees – don’t get me wrong – by all means plant them for shade, wildlife habitat, fruit or aesthetic appearance. But when it comes to saving the planet I just think that given the choice between (a) planting a tree and waiting a few years, and (b) cutting my electricity demand by 3.8 watts now, I know what I would go for.