Fullscreen HTML5Med Res (??MB)HTML4

PUBLISHER’S LETTER www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Peter Smith Ross Tester Jim Rowe, B.A., B.Sc, VK2ZLO Rick Walters Reader Services Ann Jenkinson Advertising Enquiries Leo Simpson Phone (02) 9979 5644 Fax (02) 9979 6503 Regular Contributors Brendan Akhurst Rodney Champness, VK3UG Julian Edgar, Dip.T.(Sec.), B.Ed Mike Sheriff, B.Sc, VK2YFK Philip Watson, MIREE, VK2ZPW Stan Swan SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 003 205 490. ABN 49 003 205 490 All material copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Hannanprint, Noble Park, Victoria. Distribution: Network Distribution Company. Subscription rates: $69.50 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial & advertising offices: Unit 8, 101 Darley St, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9979 5644. Fax (02) 9979 6503. E-mail: silchip<at>siliconchip.com.au ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip Low voltage halogen lamps are huge power wasters In the eyes of many people, halogen lamps are a thing of beauty, a jewel-like pinpoint giving an intense white light that makes shiny objects sparkle and gleam. They also give an unclut­tered look to the low-slung ceilings of modern homes because conventional hanging light fittings are not practical. In short, halogen lamps are the “fashion” lighting accessory in modern homes. But they are awful power wasters. Recently, I visited some older relatives of mine in their sparkling, new home. And yes, every room was lit by halogen lamps recessed into the ceilings. Well, I hate ‘em, so I did not comment on this feature. However, later on during my visit, the man of the house happened to men­tion that their electricity bills were very high; much higher than in their previous home. He also said that their new home was much hotter than their previous home and so they had to run the whole house air-conditioner for much of the previous summer. He put the high power bill down to the air-conditioner. No doubt, he was mainly correct in this assumption but he had not thought about the halogen lamps. Each room was lit by four 50W halogen lamps and because (as in most modern housing developments) the house is cheek-by-jowl with neighbouring dwellings, they don’t get a lot of natural light and so tend to leave the lights on in several of the rooms for much of the day. And I daresay, as in many homes, the place is lit up like a Christmas tree at night. So the power consump­tion of their sparkly halogen lamps is consistently high. When I remarked that halogen lamps are power wasters, he replied that he understood that they were “efficient because they run at low voltage”. This sort of misconception makes me grind my teeth in frus­tration. I even think that this misconception is deliberately encouraged by some companies, to sell more of their wasteful lamps! Well, let’s thoroughly debunk that misconception. Low vol­tage does not mean low wattage! Low voltage is not good just because it is low voltage. Yes, it is true that halogen lamps run at low voltage - ie, 12V. But a 50W lamp still draws 50 watts, regardless of the running voltage. Furthermore, the stepdown transformers used to run halogen lamps are notoriously inefficient. I would estimate their efficiency at around 80% at best - that is why they run so stinking hot! And that is why installers are warned that halogen lamp transformers need plenty of ventilation and must not be crowded in amongst ceiling rockwool insulation. So rather than each 50W halogen lamp drawing 50 watts, the total draw is around 63W. And because they do have a narrow beam, you need more of them to light a room. So if you have four rooms, each lit with four 50W lamps, the total draw is around 1000 watts. That’s the same as a single-bar radiator! So say my relatives have four rooms in the house lit most of the day (seven hours) and six rooms run for an additional five hours in the evening. That’s a total daily lighting consumption of around 14-15 kilowatt-hours. That’s a lot of heat. That also means that the air-conditioner has to work so much harder to remove it. All told, their overall consumption due to halogen lighting probably averages around 20kWh every day. Over three months, that will cost at least $180 dollars or $720 per annum. They could cut that in half by merely switching off lights in the rooms they are not using. And they could further cut it by using more conventional incandescent and fluorescent lighting. So much for the cost of lighting “fashion”. Across Australia there are tens of millions of halogen lamps, in homes and shopping centres. They are an ecological disaster. Leo Simpson www.siliconchip.com.au