Lights for Manual J. I'm not confident with the old stand by 2 watss per ft2
since the new electronic fixtures. And computors have changed a great deal.
What is everyone using for these BTU gains in J?
The new style floresents four bulb suspended ceiling fixtures, what is
appropriate to use for BTU gain?
Computors. Changing all the time.
Desktop BTU with CTR btu output?
Desktop BTU with LCD Screen output?
Laptop BTU output?
If you are talking about one flourescent light fixture and one
computer, it is easy, just neglect it in your load calc but if you are
trying to figure the load on a commercial building by researching the
btu output of a computer screen ,Then you are dowmright scary.,
29CFR (OSHA regs) define the amount of light required for various types of
commercial and industrial spaces... expressed in "foot candles".... 2 watts
per sqft is nothing more than a rule of thumb, or a wild assed guess.
When in doubt... count the number of each type of light fixture, and run the
Yes, computers are changing all the time, so it would pay to check each
one... LCD displays generate a lot less heat than CRTs do, etc.
Yes I do my homework.
Two watts per sq foot is better than nothing, at least your putting
something in for lighting, and it seems that no one knows the answer any
better than I do or they would have posted the darn btu per watt formula for
the new electonic ballist type bulbs.
First, I cant find my Manual N or D, So I'm in a catch here. so, can you
tell me what the new electronic bulbs deliever in BTU's per watt? If I
could find my manual along with others that my kids threw away I would look
it up :-) I even had to email Gary Lloyd to get replacements of his books.
Usage of watts= 3.413 btu is not correct or wise and it will get you into a
large oversizing condition.
So, once again, does anyone know what the btu's are for lights?
Yep, I can relate :-))) But I also said that I would share it with
another tech person. I've been stun twice this week with homeowers and Mark
walked off a job because of one trying to pick his education and then wanted
to do everything himself, but owned a rental on the lake!
Anyway, I just recieved an email explaining everything I needed to know, so
Also, I was informed that I was viewing something incorrectly and now I've
been set on the STRAIGHT AND NARROW again Mike !!! Praise the Lord!!!
BTW, Mark and I thought that you one reply elsewhere was good but we both
want to know what you meant when you said.....
"GOD help us all" Are you starting to get the spirit, Mike??? Good boy,
you'll be a better man for it.
Rich, I had have "spirits" around me from day one and in fact started
as one and will return as one. This is nothing new.
BTW there isnt a single "God" sitting on a throne with a beard and
septor waiting to judge you. Thats what organized religion wants you
to think to keep you in line. They want you to think there is some
kind of punishment for non-obeyance to "God".
Its not like that at all Rich, this may come as a shock you but there
is no Hell and nothing to fear from death. Although the "spirits" or
souls as I like to call them say Hell is on earth, it doesnt really
exist in the afterlife. Fearing "hell" is a waste of time. Fearing
"God" is a waste of time.
All your loved ones that have passed on Rich, are watching you. It
would please them very much to see you understand and believe what Ive
just said to you. :)
You know what the closest thing to "God is? A pet. They exibit
unconditonal love and forgiveness. Thats what "God" is.
Geo, it sounds more like a commercial load you are running so manual j,
not the best approach.
Offices with flourescent lights, I think 1.5 per sqaure foot is pretty
good, they start with the fancy low voltage stuff , dimmable
incandescent then it could be higher. Maybe there is a lighting plan
you could look at.
For work stations now with the LCD monitors I allow 100W to 150W and it
seems to be conservative, copiers and high volume laser printers etc
need to be looked at specially
Thanks Abby, finally thats something I can work with. I have been looking
for a copy of ASRAE project RP-822 for days now and can't find a copy
anywhere. My one contractor friend is on vacation and his workers don't know
where he has it
Lights, computors and copiers can be a pita for sure. So many people reply
and say to take the total watts x 3.413 and that is the BTU, which is wrong.
Thanks again, and if anyone has ASHRAE manual N numbers please post them.
The manufacturers of lighting all publish the BTU output these days, as
I remember. We're using Cooper lighting in our new building and I know
they were able to provide the data.
We've seen severe disproportional heat loading in office environments
directly related to copiers and laser printers. Abby was right... these
need a real close look. Lexmark has some data out there on lasers... I
don't know if I've ever seen any on copiers.
AMD has some pretty good data on CPU cooling, as I remember. AMD's run
hot so their info would be conservative for Intel machines (I'm told).
My gut feeling is that in a one-person-per-office scenario, standard
LCD's and workstations don't present a huge problem. Start stacking them
together and it's a nightmare. I've seen it.
No one likes to deliberately oversize systems... but it would be nice if
just a little planning was done prior to installation. You're doing the
customer right by asking these questions.
Case-in-point: We recently were working a controls project at a major
order-taking/distribution site in the Indianapolis area. The building
had a huge open area that was the 'order-taking' bull-pen... so to
speak. A consultant decided that 'associates' could be more 'productive'
if printers were placed in numerous strategic locations throughout the
maze of cube workstations. That way... they didn't have to run half-way
across the building to get print-outs (which they need only occasionally).
They didn't ask anyone but their network people if this was a problem.
For the network... it was not. But going from 2 to 16 laser printers
took it's toll on the HVAC system in a 100 x 40 zoned space. The cooling
couldn't keep up. There was no 'magic' controls fix.
They had to upgrade the system.. which was expensive post-construction.
I know we're all very focused on energy savings these days.. which is
what VS and multi-stage systems are all about. It is my own opinion that
designing for a 20% (or more) increase in load is not a bad idea these
the way things change so quickly.
After all, the systems can be somewhat 'scalable' to demand.
Wow, between all these great posts and email I'm getting an adrenalin buzz!
I can see the problem you had with those extra printers, that would really
upset the cart.
This one job is pretty simple, but I know the guy that designed the prints,
hes a 110% idiot that needs to be shown to the rest of the community.
The existing building was a grocery store and they are making three equally
divided offices in the building. The original building had NO insulation
anywhere and had TONS of the old type ballast 8 foot lights and a 120,000
btu furnace and 4 ton AC worked exceptionally well.
. The building was gutted and it went from 8" Bare block walls to R-23 walls
and r44 ceiling. and insulated glass and real doors verses those leaking
automatic doors. Now the prints say they need 14 tons of AC and 490,000
BTU's of heat!!! See why I want this right. Being so small I could fudge
it by a half ton in each unit but I know its going to be asked about the
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