Joule in the Crown

By The Metric Maven

The creators of the television series Futurama had a question about money in the future. Would there be any? After deciding there probably would be, they speculated about what form the currency might take. An early suggestion for a currency basis was the joule, but in the end they opted for the dollar. The joule seemed like a much better idea to me, what is more important to the “modern” world than energy? Energy has made life luxuriant when compared with the life our forefathers (and foremothers) experienced. The joule is the unit of energy in the metric system and would be universally recognized—well except in one country.

Recently a fellow from the local energy company knocked on my door and announced he needed to work on the gas meter. Apparently in the mid-1990’s a wireless reader was installed so it could be read remotely. The battery was at the end of its life and so it was to be replaced. I watched as the technician unscrewed the existing meter module, which has its units in cubic feet. He then replaced it with an identical module, which in the year 2014 still reads out in cubic feet of gas.

My utility company sends me a bill for energy usage each month. The word energy is even in their corporate name. Below is a scan of a recent bill’s comparison information section:

The gas and electric energy usage is offered in Kwh per month and in therms respectively. The Kwh stands for kilowatt-hours. A watt is a joule per second, so multiplying a value in watts by hours is pigfish talk. The recognized unit of time in SI is the second. For this bill, the first energy value given is 928 Kwh for the electrical energy used, but energy is internationally described in joules. When all the conversions are done, the electrical energy used for the month in SI is 3341 megajoules.

The natural gas usage is assumed to be in Therms. So what is a therm?  Well, in the US, it’s 100 000 BTU, and BTU are British Thermal Units, but not the British Thermal units used by the British, those are a bit different. These are American British Thermal Units—you know—the patriotic kind. Gas meters don’t directly measure the energy delivered, but instead the volume of gas delivered. According to Wikipedia:

Since (Natural Gas) meters measure volume and not energy content, a therm factor is used by (Natural) gas companies to convert the volume of gas used to its heat equivalent, and thus calculate the actual energy use. The therm factor is usually in the units therms/CCF. It will vary with the mix of hydrocarbons in the natural gas. Natural gas with a higher than average concentration of ethane, propane or butane will have a higher therm factor. Impurities, such as carbon dioxide or nitrogen, lower the therm factor.

The volume of the gas is calculated as if it was measured at standard temperature and pressure (STP). The heat content of natural gas is solely dependent on the composition of the gas, and is independent of temperature and pressure.

Therms “Explained” for Consumers.  It is noted that 10 therms is a decatherm (Dth) and not a dth as one might expect. This is very “metricy” sounding but clearly not metric. Therms are BTUs  (click to enlarge)

So we have to have a temperature correction, and apply a therm factor which is in therms/CCF. So what is a CCF?  Well, it’s centium cubic feet or 100 cubic feet. So  the first C is the roman numeral C and stands for 100. The second identical C stands for the word cubic and F is for foot. It is sometimes alternatively written as Ccf. MCF is also used for 1000 cubic feet. The M standing for the Roman numeral for 1000 The correction factor is used to calculate the value as if it were at STP (i.e. standard temperature and pressure). Obviously, accurate values for temperature are important in determining accurate values of natural gas usage. I assume that the average daily temperature has some relationship to this required correction factor. It does not have an obvious entry on my bill. Here is what my energy company states:

Therm Multiplier

Gas usage is defined in Therms, a measure of the heat, or energy content of natural gas in a billing period. One Therm equals 100,000 British Thermal Units (Btu). The energy content of gas changes depending on its source, the altitude and temperature at which it is delivered. After your meter measures your usage by volume (in hundreds of cubic feet and appearing on your bill as “Measured Usage”), this volume is multiplied by the Therm Multiplier to determine the units of energy consumed.

Kwh “Explained” for Consumers (click to enlarge)

The multiplier is not broken down any further and does not spell out the individual contributions. Apparently the temperature, altitude, energy content and such are all wrapped into the Therm Multiplier. The comparison section on my bill is strange, as it has natural gas printed on a line above electric as if the top line is gas, and the bottom is electric. What appears to be the case is that the Kwh value (yes I used a capital K) is the amount of electrical energy usage and the therm value is the natural gas energy usage. It is assumed the customer knows and understands this energy demarcation from the Account Summary they’ve presented.

The most straightforward way for both electric and gas usage to be described, would be in terms of energy usage with a single, simple, internationally recognized unit, but they choose not to do this. Instead, the company uses kilowatt-hours and therms. In the case of kilowatt-hours, it is a pigfish unit, which is metaphorically based on metric, but not the actual metric unit for energy, and for therms it is a semi-imperial system unit for energy. Neither of them use the internationally  accepted unit for energy—the joule.

The comparison section of my energy bill could have been written  in a  much, much clearer way, that anyone could understand, using the metric system and gigajoules:

Comparison Information

Metric Comparison (click to enlarge)

When the bill is written this way, one can immediately see the difference in direct energy cost per gigajoule between Electric and Gas. Electricity is 4.85 times more expensive per joule when compared with natural gas. One can assume that the electric usage is essentially for operating appliances and gas is used for heating, just by looking at the energy usage from this year to last. This year was sixteen degrees colder than last year, and the amount of gas usage in gigajoules was different by a factor of 2.6. The previous energy use was lower for the warmer average temperature as one would expect. One also notices what is missing in this table, the comparison cost per gigajoule from the previous year for electric and gas. This would be a very useful way to gauge the change in cost from year to year. The way the energy bill is originally written one could easily confuse the columns. When presented this way, it is clear.

The way the energy usage is presented in the actual/original bill does not allow a consumer to directly compare energy prices—which are offered by an “energy” company. This is because two non-metric proxy units are used, kilowatt-hours and therms, which have a conversion factor between them of approximately 29 (i.e. 1 therm = 29.307 kilowatt-hours).

One cannot be certain about the origins of the format of the bill I received, but I could not help but think about the word confusopoly, which was introduced in Scott Adams’ book The Dilbert Future. According to Wikipedia:

The word is a portmanteau of confusion and monopoly (or rather oligopoly), defining it as “a group of companies with similar products who intentionally confuse customers instead of competing on price”. Examples of industries in which confusopolies exist (according to Adams) include telephone service, insurance, mortgage loans, banking, and financial services.

I would like to add energy companies to the list.

Australian Gas Meter — Photo by Peter Goodyear

Electricity and Gas are pretty basic, both are sold by energy content, so despite the view they are public utilities, one can only wonder if they are not following the confusopoly model when they present bills in Kilowatt-hours and Therms. My rework of my utility bill certainly looks simpler to understand than the one that uses “our traditional measurements.” When the metric system is implemented, people can readily see it’s a system.  When energy is discussed in any context using the metric system, it is always joules, so the energy content on food packages are in kilojoules, as is a person’s energy bill in gigajoules. The metric system allows for a more integrated and systematic understanding of the world by everyone. There will always be those who will try to use metric in a non-transparent manner, but it takes much more effort than when using the potpororri of “traditional” measures currently established in the US. The joule in the crown for energy description is the joule. No matter what energy is under discussion:

Australian Subway napkin with food energy in kilojoules (kJ).  An average person burns (i.e. radiates as heat) about 169 000  kJ per month (169 MJ) (courtesy of Peter Goodyear — click on image to enlarge)
US Subway Napkin with Calories (kilocalories) and grams of fat — The word energy does not appear on the  US napkin (click to enlarge)


On a side note, New Scientist on 2014-01-04 related that since the UK phased out incandescent light bulbs there has been a considerable drop in energy usage. They state:

The average amount of electricity needed annually to light a UK home fell from 720 kilowatt-hours in 1997 to 508 kWh in 2012, a drop of 29 percent.

So  the average energy use by a UK home in 1997 was 2592 megajoules/year  and in 2012 was 1829 megajoules/year

Unfortunately New Scientist can play fast and loose with energy quantities and power values. On 2014-03-08 in an article about using batteries for energy storage from wind power they state on page 20:

Last year California passed legislation requiring the state’s energy companies to create more than 1.3 gigawatts of energy storage between them by 2020.

One could blame this technical faux pas on scientifically illiterate California legislators, but one would expect New Scientist to note this mistake, and possibly comment on it. Energy storage is in joules, the amount of energy flow out of the batteries is watts (joule/second). It is like equating the amount of water behind a dam with the flow rate of water leaving it.

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.

The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.

The third book is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.

17 thoughts on “Joule in the Crown

  1. To be fair, I’m pretty sure kWh is used for household electricity usage world wide. I don’t know of any country that bills in MJ or GJ.

  2. Quoted from article: “A an average person burns (i.e. radiates as heat) about 169 000 kJ per month (169 GJ)”

    Uhh, no! That would be 169 MJ; 169 GJ would likely put a person in spontaneous human combustion. Gotta watch those prefixes.

    Also the 169 MJ figure may be a bit light, but depends on what you want the figure to mean. This site gives mean adult dietary intake as 8700 kJ/day.
    Some of that goes into work (which eventually becomes heat when it comes to rest) and some is direct radiation from the person. Assuming average of 30.5 days/month, 265 MJ/month. Do you want the fuel demand of the person, or only waste heat generated, the difference being useful work?

    Those UK figures from efficient lighting are only the electrical energy for lighting needs, not total consumption, per the quote. Few of us (or them) use as little as 508 kW·h per year (I use more per month).

  3. I learned a new word today. “Confusopoly”. What a great word! Thank you Dilbert and Randy

  4. Here in Australia the gas bills are in megajoules (MJ) and the electricity bills in kilowatt-hours, which made my life difficult when I was a home energy advisor and had to explain peoples’ utility bills t them.

    The gas meters here all read in cubic meters as per the photo in the article and there are two conversion factors on the bill, one for the heating value and another for pressure. (The pressure factor is the same on all the bills, I’ve never seen it vary. Strange.)

    Even now, more than a generation after the introduction of metric units, it still seems strange to be talking about the energy value of food in joules.

  5. Perhaps just an oversight, but your metricated version still gives the temperatures in degrees Fahrenheit.

  6. In the novel “Imperial Earth” by Arthur C Clarke the interplanetary currency, the Solar, was backed by the kilo-watt hour, the way currency used be on the “gold standard.”.

  7. BTW, in Italy, where I live, the situation is essentially like this:

    … thus, with a mix of metric, but probably not optimal units, like for example cubic decimeters and bars (and the CE marking^ symbol is also wrong – i.e., the C and the E are too close (which today often means “China Export”…), – on the electric meter: but probably and hopefully they have corrected this, since then…).

    As Lachlan Hunt said before, the kWh is probably here to stay, probably also because it explicitly involves time, which perhaps is felt as important or more “intuitive” for billing purposes.

    Or, maybe, it’s just another example of “customary” (not only US, thus, but also metric) habit, which could easily be superseded once SI *evolves* (e.g., also with a more widespread diffusion and effective use in everyday life: today “unusual” prefixes included, etc. etc.): that would, of course, be ideal…


  8. As for money or not, in the future, not even Star Trek is so clear about that:

    It would be cool if the need for money were eventually superseded, thus evolving towards a more human society, also with the heavy work entirely automated (see robots and other more or less intelligent machines); sadly, that doesn’t seem to be the case currently, despite continuous technological innovation (but probably too focused on individual gadgets and on making profits, rather than on improving the life of humanity as a whole)…

  9. BTW, in electrical engineering, is the “var” (as in “kilovarhours” (?), or kvarh) a “real” SI unit?

    Anyway, what a mess of often redundant units, even in the supposedly already quite evolved metric system: i.e., a lack of (political will towards) – and possibly worldwide – rationalization and standardization, perhaps…

    BTW, thinking about Europe (but also appliable elsewhere in the world), there isn’t even a common standard on electrical plugs and sockets (not to talk about railway voltages, etc. etc.) – hmmm, not so good…

    • It is made of from real SI units, but it is not recognized by the BIPM. However, if you follow up on the footnotes, it is explicitly recognized by the former EEC (now EU) and the US government (probably others too), and sanctioned by IEC. It is a very important concept in ac power distribution and must have a term. Since the BIPM failed to provide one, the industry did. Also the volt-ampere is important, and it must be recognized that is NOT the same as the watt in ac power unless the phase angle is zero (power factor = 1)

      For a single phase AC circuit with rms voltage V, rms current I, and phase angle theta between,
      apparent power is simple V*I
      real power is V*I*cos(theta)
      reactive power is V*I*sin(theta)
      (these are in quadrature, forming a right triangle vector diagram, and all rules of solving such a triangle apply. Apparent power is the square root of the sum of the squares of real and reactive power.

      If reactive power is excessive (it is nearly always inductive), capacitors are added to reduce phase angle, bring power factor closer to unity. Commercial power is generally charged by the apparent power, kVAh, not by the kWh. If you don’t get phase angle under control you are charged a penalty.

      • Thanks for the eccellent explanation!

        The fact that the industry provided a unit that the BIPM failed to “create” is very interesting: and it will probably be the (worldwide) industry that eventually will be responsible for the metrication of the US, lacking a political will to do so.

        If engineers – of course as and together with citizens – “decided”, instead of bureaucrats, economists and politicians, etc. etc., the world would probably be a much more evolved and better place to live in.

        But there’s still a long way to go, before we’ll reach a possibly Star Trek-like (see before) post-scarcity and worldwide economy and society, with unified technical standards and measurement system…

        • As other examples, in chemistry, there is pH. As a matter of fact, the mole was in use in chemistry LONG before it was sanctioned by the BIPM.. I see it as OK when it truly fills a gap, and not OK when it simply avoids a perfectly good SI unit.

          A few others like the astronomical unit and parsec (from astronomy) started this way, but astronomers apparently have better lobbyists, and they are now listed by the BIPM.

          The IEC has sanctioned the binary prefixes which are multiples of 2^10 to avoid misuse of metric prefixes in relation to computer memory. That results in things like kibibytes, which sound more like dry dog food that memory units (kibibits for smaller dogs). In spite of sounding funny (maybe I’m just not used to them yet), they fill a need.

  10. Interesting, indeed…

    BTW – also returning more in topic, thus, – I remember that when I was in elementary school, in Denmark, in the mid-’70s (also with a great hippie-like teacher, who made us really enjoy learning…) of the last century, they already taught us that the new energy unit should mandatorily be the “new” Joule, and not the “old” calorie: well, those were the times, my friends – hehehe…

    That said, I must confess that, after all, I don’t think that units named after persons (even if obviously self-evident and great geniuses of the past) are a so good thing, perhaps: they don’t convey much intuitive sense of what is measured, IMHO…

    • Really? Their work was so closely related to the unit named after them that, to me, it has substantial mnemonic value. I think of Joule’s mechanical equivalent of heat experiment and think immediately of the joule. Death to the calorie and BTU.

      • One could have redefined the erg, with 1 new erg = 1 joule.

        “Erg” sounds just about perfect for an energy unit; but it was already taken by the old CGS system, and redefining it towards MKS and SI would probably have been difficult.

        Anyway, better names than the current SI ones could always be invented: especially for the kilogram, a derived base unit, something that makes very little sense (a base unit must… well, be a base unit, with a proper name, and not derived from other units!).

  11. … The same also for the dyne and other units with excellent and almost universally intuitive names – derived from ancient Greek, etc. etc. – of the old CGS system: ideally, they should have been “ported” to MKS and finally to SI, IMHO, instead of “reinventing the wheel” with sometimes strange names, related more to history than to the essence of what is measured.

    Only a personal opinion, of course…

  12. Very good blog post. There are many pigfish units out there. For example, saying that an average person burns 169 000 kJ per month is just as strange as using kWh for energy. 169 000 kJ/month is of course just a pigfish way of saying 64.3 W. Watt is the proper unit for power. The (169 MJ) parenthesis makes it worse by using the wrong unit altogether and expresses power as if it was energy, the same error that New Scientist made.

    The metric comparison information has similar problems. For an ongoing cost like energy consumption, whether the bill comes once, twice, or twelve times per year has very little relevance to the energy consumption or cost so it should not affect the comparison information. The comparison should use Watt, not Joule. To extract the actual energy usage from the metric comparison one has to first guess that the 3.172 GJ is supposed to be per year, even though it is not stated anywhere except very implicitly under the billing period. The original bill gets this right and writes all values as cost per time period and as power. Even if the original units were strange, at least they are units of power, not energy.

    The metric comparison also uses “F” which is not metric, and is also not the right symbol for Fahrenheit: °F.

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