[Equest-users] LED Lights (UNCLASSIFIED)

Peter Hillermann peterh at westallarchitects.com
Fri Oct 7 08:42:21 PDT 2011


John,

Hopefully this will help. It is an article that explains heat dissipation
with items that have small hot spots.
http://www.ledjournal.com/eprints/nextreme_sept09.html

Your discussion is far more philosophical and delves into a discussion about
embodied energy. What you are talking about below is addressing multiple
issues which are far more complex than the building energy modeling we are
doing right now. Remember that you are simulating.

I have started going down these roads and it turns out they are very
complex. Keep it simple and use averages.

Thanks,

PETER HILLERMANN

peterh at westallarchitects.com

westall
architects
3404 pierce drive
chamblee, georgia 30341

o 770.458.4113
f  770.458.5352
c 678.898.2936

westallarchitects.com





-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Eurek, John
S NWO
Sent: Friday, October 07, 2011 10:28 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] LED Lights (UNCLASSIFIED)

Classification: UNCLASSIFIED
Caveats: NONE

All,

Are LED lights really magical?  We have all used a laptop and felt the AC/DC
converter get hot.  We know that if a transformers (not the cool kind) are
inside a building they put off a lot of heat.  What about the transformers
for the LED lights?

LED lights need DC power, where are all the transformers and were does that
heat go?

I suspect the LED light is like the electric car. It is cool that the car
runs off of electricity, just don't look at the coal that is burnt to make
the electricity.  Yes LED lights give off almost no heat, but what about the
transformer?

Anybody have any information on this?  What is the heat of rejection from
the transformers.... (I have done a little research and one solution was to
have a single transformer for the building and wire the lighting of the
building with DC power.  Talk about changing business as usual.)


John Eurek 

-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of John Bixler
Sent: Thursday, October 06, 2011 8:25 AM
To: Taylor Sharpe; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Lighting densities and Electricalequipment
contributing to Space Heating

Taylor,

 

A number of things play into the question you are asking.

 

*         Different types of lighting have different efficiencies.
Incandescent lights create a lot of heat, LEDs create practically no heat.
Fluorescent is somewhere in between but create much less heat then
incandescent

*         The style of light installed - is it pendant hung in the space?
If
so, 100% of the created heat is given to the space.  Is it recessed?  If so,
a portion of the heat is given to the plenum, and some of the heat given to
the plenum leaves the building as relief air (in fact, it's possible that
all the plenum heat leaves the building in the case of a 100% outdoor air
system)

*         The schedule of the lights.  Were you looking at yearly
consumption
or peak heating load?  Peak heating load is typically calculated with the
lights (and occupancy and misc loads) at 0%.  If you were looking at yearly
consumption, but your modeled facility has the lights turned off for a
majority of the time, the impact may be minimized.

 

Point being, you have to consider more than just lighting density when you
make this analysis. 

 

John Bixler, EIT, LEED AP BD+C

Mechanical Designer

Sebesta Blomberg
sebesta.com | P  319.364.1005 | M  319.558.9299 

 

This message has been sent via the Internet. Internet communications are not
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From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Taylor
Sharpe
Sent: Wednesday, October 05, 2011 10:18 PM
To: John Bixler
Subject: [Equest-users] Lighting densities and Electrical equipment
contributing to Space Heating

 

Hi everyone,

I feel that this topic must have been discussed at some point, but an
exhaustive archive search got me nowhere, so I thought I'd throw together a
post of my own, especially since I'm working on an eQuest model of a small
server building which is heated in part by a large number of computers that
run many hours every day.

I'm interested in how eQuest treats electric loads - from lights, computers,
refrigerators, etc - as regards space heating.  I had always assumed that,
especially in the case of lights, much of the energy used would be converted
to heat within the building, and contribute to space heating.

However, I set up an experiment to test this and found that the results were
far different from what I'd expected: I upped the lighting density in an
existing natural-gas-heated building model by about 15x and compared the
electric use from before and after the lights were increased.  I converted
all values to mmBtus for easy comparison.  To my surprise, I found that only
a very small fraction (about 6%) of the mmBtus added to the building through
those lights contributed to space heat.  The kWh recorded were increased
hugely, but the heating energy required to keep the building heated was
almost the same in both cases.

I repeated the experiment, upping misc. equipment instead of lighting, and
saw a similar result.

Does anyone have any knowledge of what equations eQuest uses to decide how
much electrical energy use is converted to heat and added to the space in
which it is installed?

Regards,
Taylor Sharpe
Sharpe Energy Solutions
newspectrum at gmail.com
(541-840-5698)


Classification: UNCLASSIFIED
Caveats: NONE


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