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Too much emphasis is placed on the insulation and
other such tricks in the energy consumption in my experience. Lowering the thermostat (and putting on the ugly xmas-present
sweater) or limiting the hot water usage (showers, dishwashers) is far more
effective.
Our New England colonial household (of the
usual 150 GJ/y for a generation) recorded zero improvement
(statistical averaging) in adding attic insulation, zero improvement in
replacing a 60 years old oil-heating system with a new boiler, natural gas fired
(a few years later), etc.
On the other hand, when another person moved
in to live with us, the prior year's 145 GJ jumped promptly to 165 GJ, all
else equal. A colder weather (and do not believe that year's weather was
colder) cannot account for the difference. Shower, Jacuzzi, cloth washer and
dryer, dishwasher and other appliances do.
As a matter of fact, if the heating were to
predominate, the house should use less energy for the additional 100 W of heat
every person generates. Doing nothing, that is.
Stan Jakuba
----- Original Message -----
Sent: 06 Feb 01, Wednesday 10:58
Subject: [USMA:35936] Re: When was the
joule introduced to SI?
I keep a record of our household energy use, last
year we used 186 GJ of energy for the whole year, combined natural gas and
electric, (Pat said the average was 150 GJ) mostly due to the poor
insulation of the house we live in. The highest use was in winter. Average
$20,23/GJ. Another reason I'd like to build a well insulated solar
powered house.
----- Original Message -----
Sent: Sunday, 08 January, 2006
23:25
Subject: [USMA:35609] Re: When was the
joule introduced to SI?
This was my original note. I have collated the
responses below.
Dear All,
Can anyone give me the definitive date that
the joule was introduced into the SI as the unit for energy. I
suspect that it was at the same time as the newton, but Im having
trouble finding the right reference.
I have searched the
BIPM web site but with no
luck.
Dear All,
Many
thanks to everyone who contributed to my request for information about the
joule. Thanks for your help in tracing the official origins of the joule as
the unit for energy.
It seems that the chronology goes something like
this.
1818
James Prescott Joule (1818/1889) was born into a
wealthy brewing family in Salford, England.
1840
Joule
stated a physical law, now called Joule's Law, that heat is produced in an
electrical conductor.
1845
Joule was the first person to
measure the equivalence of work and heat, by having falling weights rotate
paddles in water.
At about this time, Joule shared in
discovering the law of the conservation of energy, which says that energy
used up in one form reappears in another form and is never lost. His
co-workers were Hermann von Helmholtz, Julius von Mayer, and William Thomson
(1824/1907) (later Lord Kelvin) and he worked with Lord Kelvin to develop
the absolute scale of temperature. Joule never claimed to have formulated a
general Law of Conservation of Energy but his experiments were certainly
fundamental in bringing about that formulation.
1881
At the
First International Electrical Congress (IEC) in Paris, five 'practical'
electrical units were defined; they were: the ohm, farad, volt, ampere, and
coulomb. This decision was based on the recommendations of a British
Association for the Advancement of Science and their recommendations were
largely based on Joule's researches on electrical energy. See an excellent
article by Robert A. Nelson at: http://www.aticourses.com/international_system_units.htm
on these and some other metric issues.
1889
In 1889, the year of
Joule's death, it seems likely that the British Association for the
Advancement of Science (BAAS) suggested the name for the energy unit to
honor the name of James Prescott Joule for his pioneering work on
electricity and energy. The BAAS promoted this idea actively and the Second
Congress of the International Electrical Conference (IEC) added the joule,
watt, and a unit of inductance that was later given the name
henry.
The joule was adopted by the IEC as the unit for energy
and work. The Oxford Dictionary of Weights and Measures quotes 'Le Système
International d'Unités (Sevres; France: Bureau International de Poids et
Mesures, 1985)' as its source.
1946
The joule was defined by
the CIPM. (SI brochure, Appendix 1, Section 2.4 (Electric current)), which
shows CIPM resolution 2 giving the definition of the
joule,
1948
The joule and its definition were ratified by
the CGPM as the official SI unit for energy. This made the joule the
official world unit for energy. Resolution 3 of the CGPM (1948)
said:
3.
The unit of quantity of heat is the
joule.
They then went on to say in a
footnote:
Note: It is requested that the results of
calorimetric experiments be as far as possible expressed in joules. If the
experiments are made by comparison with the rise of temperature of water
(and that, for some reason, it is not possible to avoid using the
calorie), the information necessary for conversion to joules must be
provided. The CIPM, advised by the CCTC, should prepare a table giving, in
joules per degree, the most accurate values that can be obtained from
experiments on the specific heat of
water.
It seems that the CGPM felt troubled by the
promoters of the calorie (or is that Calorie) even then. (This footnote has
a decidedly grumpy tone in my opinion!)
1960
When the CGPM first
defined SI, in 1960, it included the joule as the derived unit for energy.
This reconfirmed the joule as the official SI metric unit for
energy.
1998
The joule is listed in 'The International
System of Units (SI) in 'Table 3. SI derived units with special names and
symbols' as the SI derived unit for the 'Derived quantity' of 'energy, work,
quantity of heat'.
2006
Question: Why am I researching the origin
of the joule?
Answer: Recently, I was rewriting my web page on
why we should move more quickly towards the metric system (See http://metricationmatters.com/why_metrication
), when I realised that a lack of knowledge about energy, and particularly
about how to measure it using joules, kilojoules, and megajoules etc., was
seriously hampering a great deal of public debate on extremely important
energy issues.
I wrote:
Energy and
power
This lack of ability of old measures to lead to
understanding can lead to very serious problems in the world. Consider the
world's pressing need to understand how we use our limited energy supplies
and how quickly we use them. These questions directly relate to global
warming.
Fundamental concepts such as energy and power are
essentially simple in concept but they often confuse politicians because of
the numerous ways they are measured with so many unrelated units. This
complexity makes it difficult, if not impossible, for politicians to
understand even basic quantitative information about the physical world
around them. To understand the total world energy issue using old measures
is quite difficult (even for scientists and engineers) and almost completely
impossible for politicians and the rest of us.
If you want to
begin to comprehend global warming, you need to have a working knowledge of
most of these 68 old pre-metric energy measures because in the year 2006
they are all still in use:
Atomic energy unit, barrel oil
equivalent, billion electron volts, British thermal unit (16 °C), British
thermal unit (4 °C), British thermal unit (international), British thermal
unit (ISO), British thermal unit (IT), British thermal unit (mean), British
thermal unit (thermal), British thermal unit (thermochemical), calorie,
calorie (16 °C), calorie (20 °C), calorie (4 °C), calorie (diet
kilocalorie), calorie (int.), calorie (IT) (International Steam Table),
calorie (mean), calorie (thermochemical), Celsius heat unit (int.), coulomb
volt, cubic centimetre atmospheres, cubic foot atmospheres, cubic metre
atmospheres, dutys, dyne centimetres, electron volt, erg, foot-grains,
foot-pound force, foot-poundal, gigaelectronvolt, gram calorie, gram
calories (mean), hartree, horsepower hours, horsepower hours (metric), inch
pound force, Kayser, kilocalorie (16 °C), kilocalorie (4 °C), kilocalorie
(int.), kiloelectronvolt, kilogram calories (int.), kilogram force metre,
kilojoule, kiloton TNT equivalent, kilowatt hour, kilowatt minute, kilowatt
second, megaelectronvolt, megajoule, megaton TNT equivalent, megawatt hours,
newton metres, Q unit, quadrillion, quad, Rydberg, therm (EC), therm (US),
thermie (16 °C), ton TNT equivalent, tonne coal equivalent, tonne oil
equivalent, watt hour, and watt second.
In contrast, using the
metric system to consider energy is relatively easy. We know that energy is
measured in joules and that we will probably need to use some large prefixes
to understand our energy use on a global scale. Here are some figures to
consider.
If you are an average teenager you will need 11 000
kilojoules or 11 megajoules of food energy each day. This is 77 megajoules
each week 330 MJ each month and about 4000 MJ of energy for a whole
year.
You might even like to think of this as four gigajoules per annum
(4 GJ/a) as there are 1000 megajoules in a gigajoule. Even a hardworking
construction worker only needs about 5 gigajoules per annum (5
GJ/a).
In a temperate climate, an average family household uses
a bit over 100 gigajoules of energy in a year. This might go up to 150 GJ in
a cold climate.
In 2003, the USA used 112 exajoules of energy
that was made up from:
42
exajoules from petroleum,
26 exajoules from natural gas,
26
exajoules from coal,
11 exajoules from nuclear energy, and
7
exajoules from renewable
energy.
See: http://metricationmatters.com/why_metrication
for more details about why we should move more rapidly to the metric units
expressed as 'The International System of Units
(SI).
Cheers,
Pat Naughtin ASM (NSAA), LCAMS (USMA)*
PO Box
305, Belmont, Geelong, Australia
Phone 61 3 5241 2008
Pat Naughtin is the editor of the free
online monthly newsletter, 'Metrication matters'.
You can subscribe by
going to http://www.metricationmatters.com/newsletter
*
Pat is the editor of the 'Numbers and measurement' chapter of the Australian
Government Publishing Service 'Style manual for writers, editors and
printers', he is an Accredited Speaking Member (ASM) with the National
Speakers Association of Australia, and a Lifetime Certified Advanced
Metrication Specialist (LCAMS) with the United States Metric Association.
For more information go to: http://metricationmatters.com
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