Do light bulb heat BTUs Equal electric heater BTUs

Page 1 of 2  
I always wondered if leaving light bulbs turned on in the house in winter produces the same amount of heat (per wattage) as an electric heater of the same wattage.
For example, I know that a 500 watt heater and five 100 watt light bulbs will both consume 500 watts. However, will five 100 watt bulbs produce as much heat BTUs as a 500 watt electric space heater?
Anyone know?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/27/2011 4:12 AM, snipped-for-privacy@myplace.com wrote:

Approximately 90% of the power consumed by an incandescent light bulb is emitted as heat, rather than as visible light.
http://en.wikipedia.org/wiki/Incandescent_light_bulb
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The Daring Dufas wrote:

And the visible light is converted to heat when it is absorbed by whatever it hits. Ask any cat who basks in a sunbeam.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 27 Jan 2011 05:21:13 -0600, The Daring Dufas

Yes, and not only that, I'm pretty sure the remaining 10% is turned into heat as soon as it stops being light.
After all, what else could happen to it?
And it stops being light quickly, or a white room with white furniture would still be lit after you turn off the lights.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/27/2011 6:21 AM, The Daring Dufas wrote:

And the other 10%, unless it goes out the window, is also returned as heat. Weird, but true.
Jeff

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

re: "And the other 10%, unless it goes out the window, is also returned as heat."
True, but is it "efficient" heat?
By that I mean this...
My heat vents are at floor level. None of my lights are.
Most of my lights are not only above eye level, but also light up a large portion of the ceiling.
All that heat up near/at the ceiling isn't quite as "efficient" as the heat coming from my registers unless it's gets circulated back down to people level.
If it all starts at the ceiling and stays there, it's wasted to a certain extent.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 27 Jan 2011 13:04:52 -0800 (PST), DerbyDad03

Most (or at leat a fair fraction) of the heat you get from light bulbs is RADIANT heat - meaning it heats the object, not the air - so high lights pointing down heat you and the floor - which heats the air.
Forced air heating works a bit differently - so the outlets are floor level, and the hot air rizes.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 27 Jan 2011 18:02:25 -0500, snipped-for-privacy@snyder.on.ca wrote:

In that case, I think I'll just install all my lights on the floor. They would be a lot easier to install too. Just cut a whole in the floor, mount the box from the basement and wire it right to the breaker box.
I wonder if the code would require some sort of shield around the bulb for when people trip over them?
This could become a new fad. Think about this. People are boring. They have always put lights on the ceiling, except for a few on walls. That's very boring. Do something unique and different, install lights on the floor.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Jan 27, 6:02pm, snipped-for-privacy@snyder.on.ca wrote:

The majority of my "high lights" point up, not down.
The ones that point down are mostly CFL's, so they don't qualify of as "heat balls".
Most of the ones that point up have 2 150W 3-way heat balls, the others have bug-frying tungsten halogen lamps.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 28 Jan 2011 18:49:09 -0800 (PST), DerbyDad03

Yesh, but the light they emit is still light. Which turns into heat. Evenly on the walls and furniture and people, except when they are in the shadows.
As to the light on your ceiling, how many floors does your house have?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
?

Using bulbs as heaters is slightly less efficient as some of the energy is light. OTOH, I've been told that the light eventually turns to heat, but you probably need a physicist to give a good explanation of that portion.
It makes a lot of sense to use more efficient types of lighting in many cases, but in winter, that heat is not lost, but a benefit. In summer, you are paying to remove that heat with an air conditioner so the CFL is better then. Fortunately, the new CFL are much better light quality compared to the sickly green of years past.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

even so, a heat pump is more efficient at putting out heat per unit power than electric resistive heating, so it makes more sense to use more efficient lighting and rely on a heat pump for heat (assuming you have an all-electric house. If you have a furnace, the cost/benefit analysis depends on the cost per BTU of the furnace and electric resistive heating. I would suspect that in most if not all cases the furnace would be the better bet.)
Now heat pumps do have drawbacks in cold weather, unless you have a ground loop system which most people do not...
nate
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

It's good you raise this. I hadn't thought about it, but I guess they would be more efficient because they're not making heat entirely out of electricity, they're pumping the heat in from outside, where even when it's cold out (by human standards), the air has heat in it.
(If it didn't have heat, the oxygen, nitrogen, and other gases would all be solids, which would make walking out of the house impossible without a hammer and chisel. On a warm day maybe they would all be liquids, so that when you opened your front door, liquid nitrogen and liquid oxygen etc would start to fill your house. This might work out okay if you wore insulated hipboots, and I guess when everything dried most of it woudln't be damaged like water does, but you couldn't leave fruit or vegetables near the floor.)
Intuitively, there is no heat to be got from cold outside air, but I guess there is.
(For some reason they say that heat pumps are marginally a good idea in Baltimore, and not a good idea where it's much colder, but that's another topic.)

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
?

Intuitively, after removing 20" of snow from my driveway this morning you are correct. Anything above absolute zero has heat. The trick is to extract it at reasonable cost. Geothermal systems rely on the heat in the earth and that is often below the temperature we want in the house.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 27 Jan 2011 10:39:24 -0500, "Ed Pawlowski"

Really! Until just now I had an image of boiling or almost boiling lava, or at least really hot stuff like the red center in the drawing in my 7th grade science book.
It's going to take a while for this to sink in.
Is it at least warmer than the cold air outside? (I guess so or the pipes would freeze, the frost line would be much lower.) How deep do you have to go to get 50 degrees F on a cold day?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/27/2011 10:39 AM, Ed Pawlowski wrote:

I've been thinking radiant floor. Pump heat during the day and use it at night when it is usually 10 or 20 degrees colder. Wouldn't work so well in overcast weather, but in climates with sunny days storing the nights heat could be a good deal.
Jeff
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

My mother rented a house that had that, in Pennsylvania. The owner or the previous tenant didn't like it, so while my mother was there the owner replaced it with electric baseboard heat.
Nothing else was economical to install because they'd have to run air ducts or pipes, and take a lot of space in a 1-story house with no basement for the furnace.
(I think this happened before I visited so I never experienced it myself.)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Far from unheard of, hydronic radiant heatis quite common in many areas, particularly in higher end homes.
And talking about primitive, untill a decade or two ago, central heat in Britain was a "luxury"
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/27/2011 8:19 AM, N8N wrote:

Many people don't understand that a heat pump doesn't produce heat, it moves heat from one source to another. I wonder if anyone has tried an underground heat storage pit like the ice storage pits some facilities have to store cold during the winter and use it for cooling air during the summer months? I wonder if an inexpensive phase change heat storage material could be used for both heat and cold storage? Hummmmm, now I must scratch both ends in order to contemplate the concept. :-)
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

well, you've pretty much described a "ground loop" system except the bit in the ground just pretty much stays the same temp all year round (far below frost line)
I do remember reading a book on energy efficient houses that showed one house design that used a large reservoir of water underneath the house to try to even out day/night temp fluctuations.
nate
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.