Greenhouses still need light
14 Aug 2006I was doing some research today and came across this spectacularly bad greenhouse information resource from the Australian Greenhouse Office (part of our Commonwealth’s Department of the Environment and Heritage). It (mostly sensibly) advocates ways to save energy in the expensive “install energy-efficient lighting” bit, but then proceeds to soundly shoot itself in the foot under “Use lights efficiently”.
Update: I discovered a resource on the same Greenhouse site that explains things much more accurately/clearly. Or maybe just more geekily. Anyway, I found it helpful. Down the bottom of that page it’s basically point by point the same just using different words and being generally less stupid. Now all they gotta do is amalgamate resources/rewrite the “brief” copy.
“Buy and use compact fluoros instead of incandescent lighting” (sensible) versus “Modern dimmer controls reduce greenhouse gas emissions as they reduce light output. They also extend lamp life.” (ridiculous – and incompatible with CF lighting)
“Fit lower-wattage globes or compact fluorescents in bright lights, especially downlights and spotlights; save up to 50% of greenhouse gas.”
Potentially ridiculous: As increasing numbers of downlights/spots are using halogen bulbs, more are being installed to compensate for stupidly narrow beams. This doesn’t have to be the case, but people seem to opt for narrow beam lights for some reason. Replace one 80W@240V (3A) fixture with six 30° 50W@12V (1.5A) + transformer power consumption (varies) — you’re really not saving much. ALSO, there is no CF alternative to halogens so far as I know. There ARE some LED products on the market, but they’re probably a garish blue (or at least a fair way from the 3000K temperature we generally expect from domestic lighting) and still cost upwards of $AU25/unit, versus about $5 for a regular halogen. The obvious advantage here is that they don’t require reflectors and will thus automatically have a wider coverage, along with rubbish total cost of ownership stuff that no-one really cares enough about to pay attention.)
“Reflector-back lamps of lower wattage provide more useful light in downlights or spotlights while generating less greenhouse gas.”
Potentially ridiculous: what did I just say? Yes, this is helpful, no, it’s not the best option. Think of it as reducing the evils of halogens (except for where you need/don’t mind 270°+ vertical light coverage, which is sometimes).
“Low voltage halogen lamps are not necessarily low energy lamps: each one generates one kilogram of greenhouse gas every 15 hours – about the same as an ordinary 60-watt globe – although they do produce more light.”
Potentially faulty maths I don’t know how they arrived at that figure. But then again I’m an English major so there we go. They must have really pumped the transformer figure, OR they’re talking about the mythical 240V halogen — a creature rarely found in the wild, but rumoured to exist. Hardly ever in use.
“Use light fittings which allow maximum light to pass through – coloured glass often cuts light output by half, creating a need for higher-wattage lamps.”
Good call. Completely irrelevant to domestic settings. Well, kinda. Unless they’re expecting people to rip apart their lamp-shades today. Maybe in twenty years when we’re out of fuel and are struggling to start a fire huddled in a cave… yeah, right.
“A 20-watt compact fluorescent provides as much light as a 100-watt incandescent.”
Sure. Which is all fun and games until you’ve been conned into purchasing them by above disinformation thinking they’ll cope okay with your crappy variable pot dimmer. Then, out go the incandescents when Joe Consumer thinks they break too quickly.
“A 20-watt compact fluorescent provides as much light as a 100-watt incandescent.”
Yup.
“Timer controls and daylight or movement sensors are now available to switch off lights automatically.”
They sure can. Great for keeping your house dark, not so great for cutting emissions. Insert vague statistics about the amount of unnecessary power consumed by devices on standby in the average domestic setting each year. Some small benefit might be realised, but you’d be better just cultivating a habit of turning off lights when leaving rooms.
“Use light-coloured paint inside your house. Dark wall colours absorb light, increasing the amount of lighting needed.”
Revolutionary. Sorry, I shouldn’t be so sarcastic… this is a good point. I’m not sure whether the wall colours magically absorb light or simply fail to reflect it. Or if there’s even a difference between the two. I’m all out of smart-arse ammo on this point.
“Modern dimmer controls reduce greenhouse gas emissions as they reduce light output. They also extend lamp life.”
Debunked above. Stupid consumers aside, I think there’s probably a decent-sized question of efficiency here, also. How about you just buy lower wattage globes to start with?
“Use desk lamps or standard lamps where light is most needed, so less lighting is required in the rest of the room.”
Huh? What, the desk lamps you can’t buy CF fittings for? People use too-high wattage incandescent globes (60W-ish) or still-too-high wattage halogens (20W), and then proceed to have two or three on to compensate. I’ve seen it happen. You can get some appropriate low-wattage fittings for this purpose (standard fluoros or, sometimes, screw/bayonet CFs if the lamp supports it) but I’m still doubting the practical helpfulness of this one.
“Keep lamps and fittings clean: dirt build-up will reduce light output over time.”
Good call. Especially with really high wattage fixtures (theatre luminaires can often do with a good wiping down!) Equally, this applies to windows. Seriously. If you’re stuck in an old, musty church building and are having trouble seeing, go clean a few stained-glass windows. You don’t notice the grime as readily as you would with clear windows, but it will definitely make a difference if they ever get hit by sunlight (and even if they don’t). Particularly this applies if you’re near any major roads.
“Use daylight instead of artificial lights – but do not overdo it. Large windows and skylights add to summer heat and winter cold.”
Yup. This ties in to my last point.
So, take government fact sheets with a grain of salt. I don’t know whether the document was written by well-intentioned public servants or misinformed, wildly-optimistic hippies, but the fact remains it seems to miss a fair few key problems/misrepresents a handful of things. And yes, I’ve probably misrepresented things, too… I can get away with it because I’m just an opinionated blogger/Arts student — they’re supposedly the authority. So if I’ve got anything wrong be gentle ;-)