Pat Naughtin
Tue, 10 Aug 2010 00:28:12 -0700
Dear Martin, John, Carleton, and Stan,It seems to me that measuring, recording, and reporting energy in joules and power in watts is the simplest way to go when we are discussing anything to do with energy and/or power.
Of course you might use an appropriate prefix to provide most of the amounts you discuss are in whole numbers. You might choose kilojoules for food energy, megajoules for small engines, and gigajoules, petajoules etc for larger amounts.
I find it difficult to understand why many engineers and scientists seem to avoid the word joule altogether preferring to use mongrel measures such as kilowatt-hours instead of the SI unit, joule.
This is a worry as scientists try to communicate their ideas on such things as climate change to journalists and politicians who often have no idea that energy and power are two totally different physical concepts/
Cheers, Pat Naughtin Author of the ebook, Metrication Leaders Guide, see http://metricationmatters.com/MetricationLeadersGuideInfo.html Hear Pat speak at: http://www.youtube.com/watch?v=_lshRAPvPZY PO Box 305 Belmont 3216, Geelong, Australia Phone: 61 3 5241 2008Metric system consultant, writer, and speaker, Pat Naughtin, has helped thousands of people and hundreds of companies upgrade to the modern metric system smoothly, quickly, and so economically that they now save thousands each year when buying, processing, or selling for their businesses. Pat provides services and resources for many different trades, crafts, and professions for commercial, industrial and government metrication leaders in Asia, Europe, and in the USA. Pat's clients include the Australian Government, Google, NASA, NIST, and the metric associations of Canada, the UK, and the USA. See http://www.metricationmatters.com for more metrication information, contact Pat at pat.naugh...@metricationmatters.com or to get the free 'Metrication matters' newsletter go to: http://www.metricationmatters.com/newsletter to subscribe.
On 2010/08/10, at 15:34 , Martin Vlietstra wrote:
We are drifting into the “Green” argument here which is outside the remit of this board. However noting that the best way to quantify “Green” arguments by using a single, consistent unit of energy is well within the remit of this board.From: owner-u...@colostate.edu [mailto:owner-u...@colostate.edu] On Behalf Of Carleton MacDonaldSent: 09 August 2010 23:10 To: U.S. Metric Association Subject: [USMA:48344] RE: Air-conditioningTrue. But nonetheless if all of that stuff in the house raises the internal temperature one degree Celsius, that’s one fewer degree the furnace has to work to get the house up to the setting on the thermostat (which in our house in the winter is 20 degrees Celsius).Carleton From: John M. Steele [mailto:jmsteele9...@sbcglobal.net] Sent: Monday, August 09, 2010 07:07 To: carlet...@comcast.net; U.S. Metric Association Subject: Re: [USMA:48340] RE: Air-conditioningI agree with Martin's response, but the more immediate effect to you is that you are heating at electricity rates, which are normally much higher than natural gas or other heating fuel rates.Use the electricity you need to, but the waste heat is a cost- ineffective offset to heating fuel use in winter and pure waste in the summer.From: Carleton MacDonald <carlet...@comcast.net> To: U.S. Metric Association <usma@colostate.edu> Sent: Sun, August 8, 2010 9:23:19 PM Subject: [USMA:48340] RE: Air-conditioningOn the other hand, in winter, wouldn’t all that heat mean the furnace has to run less often?CarletonFrom: owner-u...@colostate.edu [mailto:owner-u...@colostate.edu] On Behalf Of Stanislav JakubaSent: Sunday, August 08, 2010 15:34 To: U.S. Metric Association Subject: [USMA:48339] Air-conditioningUndoubtedly, the USA members on this forum noticed the flood of air- conditioning energy-consumption news. I responded to one of these. That Letter to Editor is below, and I am adding a paragraph beneath it for USMA that addresses SI units.Letter to Editor:The "How Air Conditioning Is Sapping Our Society" omitted one reason for the skyrocketing air-conditioning electricity consumption. It is not just the growing number of air-conditioned homes that contributes to the steep rise, it is also the higher electricity consumption in homes. And in commercial buildings for that matter.As everyone was taught in school, all electricity at home changes into heat. Thus the electricity consumed by each lightbulb, TV, stove, computer, freezer, down to the cell-phone charger, heats the building interior thereby raising the temperature if the walls are not "cooling" such as in hot weather. More then in the past, these electricity consuming devices are left on longer such as lights burning during daylight for decorative purposes, computers and TVs always on (and when off they still consume electricity unless unplugged), icemakers running at full tilt, dishwashers providing electrical drying, etc. In commercial buildings, there are more lights, more computers and devices on 24/7. In supermarkets there are heat blasting bakeries, cooled food counters, drinking water and soda-fountains, freezers, etc. whose coolers are not vented outside. The heat the compressors in these devices generate must also be removed by the main air-conditioners in addition to their basic load of cooling people, walls and ceiling. It all adds.Air-conditioners use close to the same amount of electricity for the removal of heat as is consumed by the individual appliances. To illustrate, it takes between 50 W to 100 W by the air-conditioning compressor motor, fan and controls to remove the heat flow a 100 W lightbulb produces. Total power: up to 200 W. Conversely, a simple turning off (better yet, unplugging) appliances in the hot, humid weather saves up to twice the amount of electricity they would consume.And it is not just air-conditioners that gobble electricity for cooling. Ice makers are another culprit. About 1 kg of ice is melted/ made for every person in the US daily. If melted inside the home, some of the energy helps cooling the interior but most of the ice goes "down the drain" cooling the underground and picnic grounds. I calculated that 2.5 GW is utilized for ice making in the US. That is more than the capacity of the nuclear power plants in Connecticut combined. Or, to involve renewables, the power of some 12 500 typical wind mills.Lastly, the misuse of fans. Leaving a 500 W fan on in a closed room when nobody is there, as is often done in homes, schools, and businesses, is not cooling it. To the contrary, it is adding 500 W to the room thereby heating it. It is the evaporation from skin and convection that cools us; the wind only intensifies it. When there is an air-conditioner on concurrently with the fan and nothing to evaporate, another 500 W load is added to the compressor, a total of up to 1 kW more is spinning the meter.USMA members will appreciate this addition:Many writers of the air-conditioning, energy-consumption analyses illustrate the numbers on the example of the 100 W lightbulb as above. Then they take the Btu rating of an air-conditioner and thru convoluted conversions among various energy and power units provide a number in yet another unit. In the analyses, they often refer to Btus and omit specifying whether it is Btu per something such as per hour or minute. Contrasting, the “tons of refrigeration” is treated as an energy unit. And sometimes units are invented as if these I-P- units numbers were not hard enough to compare even if the terminology were unified.Why, oh why, don't writers recognize that since all (or most) electricity coming to a house changes to heat, and that both electricity and heat can and should be measured in the same unit? If they did, one would learn that to remove 100 W heat flow coming from that lightbulb requires up to 100 W electricity flow into the air- conditioning unit to power its fans, compressors, and controls. That would reduce the usual gibberish to the simple "a 100 W lighbulb, if lit, requires up to 100 W of electrical power to remove its heat in hot weather." To be a bit more informative, a writer could add that if the electricity comes from thermal power plants, it takes 300 W of fuel energy flow to power the 100 W lightbulb and consequently 300 W to power the air-conditioner, or 600 W altogether. And perhaps also hint that a person contributes about 100 W sitting idle. Not much can be done about the latter load short of going outside, which, come to think of it, may be healthy as well as frugal. The impact of metabolism is obscured by the usage of the DV measured in Calories (or calories) in the U.S. so that nobody can correlate that heat production to cooling without converting.Stan Jakuba