Anyway, it's less costly the more efficient your gadgets are at doing what they are supposed to do. More costly if they do other stuff besides what they were intended for.
Light bulbs.
- Thread starter petros
- Start date
Yeah. Heat pumps are worth the cost, too, as is geothermal gear, if you have the landscape for it.
If someone is looking to be more energy efficient, leaving incandescent light bulbs on in your house is a really poor method.
Just as a simple example, suppose your house has a volume of 300 cubic meters, 10m long, 10m wide, and 3 m high. You have say 5 100 watt bulbs to light the space. That means every second, 500 joules of energy is given off by the incandescent bulbs.
The density of air is 1.2 kg/m3, so we have 360 kg of air in the house. Air has a specific heat capacity of 1000joules/Kg°C.
So, the change in temperature will be:
100j=1000j/Kg°C*∆T*360kg
∆T=0.000278°C
So, every second that you have your 5 100watt incandeacant bulbs turned on, you are heating the house by 0.000278°C. That's one degree celcius for every hour the lights are left on.
Just as a simple example, suppose your house has a volume of 300 cubic meters, 10m long, 10m wide, and 3 m high. You have say 5 100 watt bulbs to light the space. That means every second, 500 joules of energy is given off by the incandescent bulbs.
The density of air is 1.2 kg/m3, so we have 360 kg of air in the house. Air has a specific heat capacity of 1000joules/Kg°C.
So, the change in temperature will be:
100j=1000j/Kg°C*∆T*360kg
∆T=0.000278°C
So, every second that you have your 5 100watt incandeacant bulbs turned on, you are heating the house by 0.000278°C. That's one degree celcius for every hour the lights are left on.
For people not used to dealing with metric:
The house we bought when we move to Nanaimo from Gabriola Island has electric baseboard heating. The one thing about electric heat is that it is for the most part 100 percent efficient. One watt of elecricity over an hour provides 3.412 btus per hour. If we have electric lights, the heat given off by the lights helps to heat the house, and the house doesn't know where the heat is coming from. If we have air conditioning, the heat given off by the lights adds to the cooling load.
Efficient maybe but cheap, hell no. Any heat a light bulb would supplement to interior warmth would be lost in 5 secs when letting the cat out to pee when it is -20C.
That discussion reminds me of people insisting on insulating their water heaters, because of all the heat 'lost'...I pointed out that the heat is only 'lost' during times when you are not heating your house (assuming the water heater is inside the heated part of the house).
When you let your cat out in -20 temperatures there is going to be heat lost but it doesn't change what I said. If your house has a total heat loss of 90,000 btuh, the heat from a hundred watt bulb is not very significant but it is there. If you have twenty such light bulbs, it becomes 20x100x3.412=6824 btuh. Still not a lot but it is there.
what you want to achieve, is maximum result for amount of energy put in. Your lightbulbs/hotwater tank/dryer, can not heat your house as effectively for the energy put into them, as a high efficiency furnace can. You get your lights to only light, your hot water tank to heat only the water, and your furnace to heat the house as efficiently as you can, and you will be ahead in the energy game, rather than somehow justifying it because you've got residual heat bleeding off of stuff. And your summer cooling bill, if you have one, will be much lower as well. Win win win.
For whatever reason our(electric) hot water tank is in a little closet off the kitchen. If we planned on air conditioning the house we might have decided to insulate the water tank but it is a new tank and the new tanks are pretty well insulated from the factory. Probably not worth the effort..
Cool. Assemblies like that can go up into the hundreds for one bulb. I think it's probably got something to do with converting from AC to DC and stuff like that. I spent about $130 on a lamp for the computer and it had an array of 15 LEDs. It only lasted a few months though. Les took it apart and found out why. The little circuit board inside frazzed. It was made in China. The only piece that was made there happened to be the only piece that failed.This is the type I was talking about and the price was indeed $15 ea.
The whole point was in replacing incandescent bulbs with any other bulb, the heat loss is greater and less cost effective than the replacemant bulb. Nothing to do with any other type of heat source.
Your lights will always give off heat and so will your hot water tank and clothes dryer. Your furnace will never be one hundred percent efficient. In the Winter your house will always have transmission heat losses and infiltration losses as air leaks in to replace that air blown out by range hoods and exhaust fans. The best you can do is make sure your house is properly insulated and that you are not throwing anymore heat away than absolutely necessary.
I have a natural gas hot water heater. It's about 4 years old and like yours, sits in a closet (off the laundry room). The only source of heat it gives that room is from the pilot light. Newer HW tanks are glass lined and insulated.
Water tanks have been glass-lined and insulated for quite a few years now. New HW tanks are better insulated than they were ten or fifteen years ago, but they are still full of 140 degree water and they do give off heat. In the Winter this heat is welcome but in the Summer, if you have air conditioning, it adds to the cooling load.
Yup. But wouldn't you rather have your clothes dryer drying your clothes more efficiently? Wouldn't you rather have a light bulb producing more light? Leave the heating up to those things that are meant for heating and let light bulbs light, etc. As soon as you have various things multifunctioning, they lose efficiency and it costs you more in energy.
Go for a bicycle ride and you have pretty good efficiency. Load up your bicycle with something, use the same route, same speed, you lose efficiency because you have to add more energy in order to get the same amount done with the bike.
You get a new car and go for rides. Get a trailer so you can use the car to tote stuff around and you have to add more fuel to go the same places.
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