Heat, humans VS computers?

[Sunner]

Not exactly sure if this is HT or not, but here goes.

Was watching The Matrix for about the 100'th time yesterday, and when it came to the part where Morpheus spoke about a body generating 25.000 BTU's of heat, I couldn't help but wonder how that compares to a fairly new computer along with a decent monitor.

Now, I haven't got a clue about BTU's really, so I dont know how that is, or about BTU vs Watts, but thats why Im asking here.

Is there any easy(as in graspable for me) way to compare the heat generated by a computer and a human?
Say Im sitting in a closed room, working on a computer using up 200W of power, and a monitor using 130W.

Who generates the most heat, me or the computer/monitor?
I understand that this varies greatly depending on computer/person, but just generally?

 

[CTho9305]

well, a sciam article said the human brain is a 25 watt device

 

[Armitage]

some specs I have from a vendor show a dual 1.6 GHz athlon as drawing 240 Watts.
1 BTU = 1055 watt-seconds = 3.4123 watt-hours
which comes out to about 819 BTU/hr

Now add in whatever the monitor comes to.

 

[Agent004]

<< well, a sciam article said the human brain is a 25 watt device >>



what about the whole human body I know it depends on your age, mass, volume, surrounding temperature and so on....

 

[Evadman]

25,000 BTU's seems really high for the human body. the grille in your backyard has a BTU rating of between 30 and 40k. If the human body put out that much, I think it would burn itself up.

Of course this is just speculation, I have no backed up arguments. I was not a student of biology. I will look around.

 

[Evadman]

Maximum cooling capacity of the human body when acclimated to a hot climate is 2.4 Kilowatts / day. (2400 watts / day = .1kwh ) Average computer uses .3kwh ( 300 watts)

More good info here. Also lists average wattage human body uses as 100 watts.

deff's 1 hp = 2545 Btu/hr = 746 watts.

330 btu's / hr The human body gives off heat, about 390 Btu's an hour for a man, 330 for a woman.

@ 100 watts, the body would do 2400 / day = 8,100 btu's / day. ( using the above 2545 btu's for 746 watts )

 

[Haircut]

You can work it out from the number of calories consumed in a day.

1 Kcal = 4184 Joules
If someone consumes 2,500 calories per day this is 10460000 joules per day, or 121 Joules per sec = Watts

In short divide the number of calories consumed in a day by 20.65 to get the wattage.

 

[Armitage]

<< You can work it out from the number of calories consumed in a day.

1 Kcal = 4184 Joules
If someone consumes 2,500 calories per day this is 10460000 joules per day, or 121 Joules per sec = Watts

In short divide the number of calories consumed in a day by 20.65 to get the wattage. >>



That assumes of course, that the system is in equilibrium! Something that I've been having some trouble maintaining lately

 

[Haircut]

Yeah, by 'consumes' I meant how much the body burns up, not how much you actually eat.
This calculation will not work for fat bastards who eat far too much

 

[geekender]

<< If the human body put out that much, I think it would burn itself up. >>

...a thinly veiled proponent for spontaneous human combustion?

 

[Evadman]

<<

<< If the human body put out that much, I think it would burn itself up. >>

...a thinly veiled proponent for spontaneous human combustion? >>



Nah, just thing about 25k BTU's. That's a lot of energy.

 

[Armitage]

<<

<<

<< If the human body put out that much, I think it would burn itself up. >>

...a thinly veiled proponent for spontaneous human combustion? >>



Nah, just thing about 25k BTU's. That's a lot of energy. >>



Yea, to put it in perspective ... my 1600 ft^2 house has a 125K BTU furnace (which is to big for the house).
So if the Matrix figure were correct, I could just invite 4 friends over to heat the house and wouldn't need the furnace.

Another perspective ... a typical gas-log fireplace puts out between 20 and 40 KBTU/hr. You don't feel quite that warm standing next to somebody do you?

 

[MrDudeMan]

i think it is relative


its not literally saying you will feel that heat coming from their body


i think that is the addition of what we burn + what we expel through pores, orifices, etc.

or i could be totally wrong, but i dont think it was meant to be taken 100% literal

 

[XFreebie]

matrox is a graphics card. matrix is the movie...

 

[Sunner]

Wanna nitpick huh?
Matrox is a company, G400, G450, G550 etc are graphics cards, how's that for notpicking?

Anyways, seems like I would be the major offender in generating heat then, especially considdering Im a rather big fella.

 

[Belegost]

The important thing to note here is that BTUs are a time independent unit. Given enough time a human body could probably produce 25000 BTUs and more.

 

[Armitage]

Actually, BTU by itself is not a time dependent unit. It's just a unit of energy, like calorie, joule, etc.
In common use however, when somebody says "a 100K BTU furnace" they almost certainly mean 100K BTU/hour.

So, to say that the human body generates 25K btu is somewhat meaningless. If they mean 25K BTU/hour they are clearly wrong. If they mean 25K BTU in some period of time, it doesn't mean anything without the time period (it would be about 3 days).

 

[mee987]

<< Actually, BTU by itself is not a time dependent unit >>


you appear to disagree with him, but you are still saying the exact same thing

 

[Armitage]

<<

<< Actually, BTU by itself is not a time dependent unit >>


you appear to disagree with him, but you are still saying the exact same thing >>



No I'm not. I'm pointing out that the common use of BTU is wrong. ie. stating the capacity of a furnace as "100000 BTU"

Actually, here is a link that points out exactly that: linkage

If I tell you to give me 100000 BTU of heat energy, you could deliver it in an instant with a small explosion, or stretch it out over a year with a trickle of water at slightly > room temperature.
Neither is going to be what I need to keep from freezing my tail off in my house tonight. For that I need a 100000 BTU/hour furnace.

 

[mee987]

<< Given enough time a human body could probably produce 25000 BTUs and more. >>




<< If I tell you to give me 100000 BTU of heat energy, you could deliver it in an instant with a small explosion, or stretch it out over a year with a trickle of water at slightly > room temperature. >>



I dont mean to be argumentative, but... same thing

 

[Armitage]

No.
BTU by itself is a unit of energy. No time dependence at all.
BTU, as it is commonly used, refers to a rate of production or delivery of energy, and is more properly stated as BTU/hour.

 

[Def]

<< The important thing to note here is that BTUs are a time independent unit. >>



What he said...............

 

[mrzed]

You can work it out from the number of calories consumed in a day.

I think people are forgetting that the human body moves.

Even if you just "stay still" your lungs are moving air, and your heart is pumping blood. Last I heard, movement requires energy. The number of calories you consume has a relation to the amount of heat you output, it can't be used to calculate it.

 

[Armitage]

<< You can work it out from the number of calories consumed in a day.

I think people are forgetting that the human body moves.

Even if you just "stay still" your lungs are moving air, and your heart is pumping blood. Last I heard, movement requires energy. The number of calories you consume has a relation to the amount of heat you output, it can't be used to calculate it. >>



That energy eventually becomes heat.

 

[BD231]

I never remeber Morphius saying 25,000 BTU's, he only said "At any given time, the human body generates 25 BTU's of body heat". Human body heat is a very weak form of energy, and aside from helping the body to keep a certain temp, it's completely unused. The human body gets energy only from food, vitamins and crap like that(sunlight as well). Heat generated from a computer comes from electricity, not the computer itself. If you were to shoot a constant beam of electriciy into a peice of metal, the metal would get hot, but the metal(silicon) itself would not be generating the heat, it would only be conducting the electricity in the only possible way it could which is heat, and I'm sure you know how cunduction of electricity works. So basicly, you can think of a computer as a big hunk of specialy designd metal that requiers energy in its most concentrated form, and whatever it dosn't use, it passes along as heat. Power supplys are what keep computers from exploding by the way.