Greening Your Home - Penny wise and pound foolish

Penny wise and pound foolish. Saving energy is not obvious. Worried about a 5 watt VCR standby when the 6 bulb dimmer switch is all the way down but not off (using 600 watts). Replacing a 90 watt tube TV with a 500 watt plasma or LCD. Great if you need the heat, sucks if the AC's on. Incandescent is 3X brighter than compact fluorescent for short moment lighting like finding the cookies, going to bed or nature calls. Watt miser florescent forcing me to install more fixtures. Insulation, efficient appliances and passive gain is the best bang for the buck now.

Penny wise and pound foolish. Saving energy is not obvious. Worried about a 5 watt VCR standby when the 6 bulb dimmer switch is all the way down but not off (using 600 watts).
Mcircus, you make some interesting points, but I'm not so sure I fully understand your point. If someone had 6, 100 watt bulbs on a dimmer, almost shut off, are you saying you would draw 600 watts because it is not fully shut off? I would expect it to be way less then the full draw rating.

Replacing a 90 watt tube TV with a 500 watt plasma or LCD.
This one really confuses me. Are there really LCD's that draw 500 watts? Who makes these monsters?

Regards,

Eric D

The light dimmer thing blew me away when I heard it in the elect. course. The 50" plasma I was checking out used over 500 watts with a dimmer (saving mode?) over 450 watts. You'll have to check and tell us what LCDs consume.

Penny wise and pound foolish. Saving energy is not obvious. Worried about a 5 watt VCR standby when the 6 bulb dimmer switch is all the way down but not off (using 600 watts). Replacing a 90 watt tube TV with a 500 watt plasma or LCD. Great if you need the heat, sucks if the AC's on. Incandescent is 3X brighter than compact fluorescent for short moment lighting like finding the cookies, going to bed or nature calls. Watt miser florescent forcing me to install more fixtures. Insulation, efficient appliances and passive gain is the best bang for the buck now.

I was wondering about the light dimmers in my house. I noticed they needed about 1/2 of a turn before any lighting was noticeable. But they needed to be turned to within about 1/3 of OFF, before the light bulbs went completely off.

So, I measured the voltage using a digital VOM. I was pleased with the results. When turning ON, there is no voltage out, until about 1/2 way up, then it suddenly turns on with about 50VAC.
When turning the bulbs down, I could get the voltage pretty low (and bulbs very dim) until the control hit the bottom 1/3 range. Then, the VAC suddenly dropped to 0.00 VAC.
So, unless you are extremely careless, you are likely not wasting any power when the dimmer is within 1/3 of OFF.
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My wife uses a 42" Plasma EDTV in the den. It uses 345W.
Looking at the specs on-line, I see many 42" LCDs use between 200 and 250 watts.
So, there is around 100 Watts of extra heating with the Plasma. Since there is so much glass in the den, it's nice to have a little extra heating. :)
IIRC, the old 1990s NEC 27" TV we had in the den used about 200W, but I think it used a lot more in standby mode, since the filament in the CRT was partly on (for instant-on).
The 42" Plasma uses 0.5W in standby mode.

In the summer, it seems we don't watch much TV during the hot part of the day. At night, only the bedroom is cooled, with it's own little 540W EnergyStar window AC .

My new living room 20" LCD HDTV uses a mere 55 Watts.
The 14" CRT (2 years older) TV it replaced, used 80 watts.
So, I'm the Green guy in this house! :)

Cheers,
Rich

A little older thread, but since someone brought it back to life......

My understanding of the standard house dimmer is that its basically a rheostat? Which means that the voltage (current?) not being sent to the fixture is being dissipated by resistance in the dimmer. Its not like you can just feed the 'unused' voltage back to the panel...lol. That means if the dimmer is not completely off, breaking the circuit path, you are using power. It's just being wasted as heat in the dimmer vs heat and light at the bulb.

Someone please jump in and correct me if my thinking is skewed.... Its been quite a few years since my AC theory classes.

A little older thread, but since someone brought it back to life......

My understanding of the standard house dimmer is that its basically a rheostat? Which means that the voltage (current?) not being sent to the fixture is being dissipated by resistance in the dimmer. Its not like you can just feed the 'unused' voltage back to the panel...lol. That means if the dimmer is not completely off, breaking the circuit path, you are using power. It's just being wasted as heat in the dimmer vs heat and light at the bulb.

Someone please jump in and correct me if my thinking is skewed.... Its been quite a few years since my AC theory classes.

Nope, it uses semi-conductors called thyristors or triacs.
They work like high speed off-on switches that turn on for less time when in 'dim' mode and more ON time in bight mode.

When they are in the ON mode, they have very little resistance, so they tend to dissipate a very small amount of heat. (As waste).

Very similar to the variable speed trigger on your AC power drill. Use the drill and it's speed controller devices don't heat up very much at all. If they used regular series resistance,
you would not be able to hold the drill. It would be smokin! :)

Mcircus, you make some interesting points, but I'm not so sure I fully understand your point. If someone had 6, 100 watt bulbs on a dimmer, almost shut off, are you saying you would draw 600 watts because it is not fully shut off? I would expect it to be way less then the full draw rating.


This one really confuses me. Are there really LCD's that draw 500 watts? Who makes these monsters?

Regards,

Eric D

cnet has a large comparison of energy usage of TV's
http://reviews.cnet.com/4520-6475_7-6400401-3.html?tag=lnav only one LCD uses over 500 watts, the Sharp LC-65D90U a 65 inch TV. Rear projections tend to be the most energy efficient using around 0.11-0.12 watts per square inch of screen (the worst plasma uses 0.62).

jvbish,

Very good link! Thanks for posting it.

Can someone explain the difference between DLP and LCD? Are they the same?

Thanks,

Eric D

Our Toshiba 42" LCD TV uses 169 watts. It's the Playstation 3 that chews through power like there's no tomorrow. Ironically since it plays DVDs, BluRays, CDs, video games, and acts as a wireless media player, we were able to get rid of our DVD player, CD player, and gaming console and replace it with one piece of equipment. We don't watch much TV or play games often, maybe 6-8 hrs a week, and only use the media player feature when we have friends over, but I was disappointed at how inefficient the PS3 was.

I will note that as we are remodeling we are caulking and insulating all the cracks in this 17 year old log home (talk about leaky!) and replacing the seals too. We're putting in glass doors and skylights to reduce the amount of electric lighting we need by day. When we started you had to turn on lights in nearly every room just to see what you were doing even in the daytime - now it's only at night. Since we heat primarily with wood, the heat loss through the glass is actually a blessing. (No need for AC at 8300 ft)

jvbish,

Very good link! Thanks for posting it.

Can someone explain the difference between DLP and LCD? Are they the same?

Thanks,

Eric D

DLP and LCD projection are similar. Both use a bulb, mirrors and project. Both are nearly obsolete already.
The newer thin LCD XBR Sony blows my Sony lcd projection away. so much brighter.

as info: 50 lcd projection - on about 9 hrs/day.
costs: 13 cents/day, .97 cents/wk, about 51 bucks/yr.

fred

Gunguy (love that screenname), Xring:

I believe you're both right.
The old-style dimmers were just rheostats (variable resistors), which wasted the energy not used for lighting into heat.

The newer electronic ones do not.

So it depends on which one you have. The ones in my parents house are original, installed in 1967.

I believe you can still get the rheostat or resistance type dimmers, they are cheaper. Which means that's what most people are buying.

LCD flat panel tv's use alot less energy than plasma flat panels. And until a year ago I would have said that the plasma is hands down a better product given quality of display. But LCD's haved matched them, and I think plasma will be on it's way out.

DLP uses a superfast spinning color wheel and thousands of tiny mirrors. It usually gives a better picture than LCD, but sometimes has a rainbow effect on the edges, due to the color wheel. LCD's sometimes have a screen door effect, where you can see the pixels. Generally only noticable to aficianados.

I replaced my old beer fridge in garage with an Energy Star new fridge.Trouble was that once it got around freezing point in garage,new fridge never kept anything cold.I had to move it in the house or heat the garage.
I bought a new dryer and put a vent with a styrofoam ball to keep the cold from coming in.Turns out after a year it created so much heat it burned dryer out and cost $200 to fix.I give up.:wall:

I replaced my old beer fridge in garage with an Energy Star new fridge.Trouble was that once it got around freezing point in garage,new fridge never kept anything cold.I had to move it in the house or heat the garage.
I bought a new dryer and put a vent with a styrofoam ball to keep the cold from coming in.Turns out after a year it created so much heat it burned dryer out and cost $200 to fix.I give up.:wall:


So when it was around 0*C, your fridge was actually heating things? Why not just unplug the fridge and leave the door open?