[Equest-users] LED Lights (UNCLASSIFIED)

[Charles Holleran]

LED's use DC power, and do so efficiently.  Sounds like you're referring to the AC-to-DC power supply though, not the LED light source itself.
 
As described in your post below ACDC power converters can be loosely lumped into 2 categories:
- old, inefficient, big, hot, LINEAR converters with their big transformers, and
- newer smaller, cooler, SWITCHING converters ("the cool kind" referred to below)
 
I think Enerstar has done a lot to phase out the inefficient LINEAR converters.  You can still procure the LINEAR power supplies.  But you probably won't find one that meets Enerstar requirements.  The SWITCHING supplies are much more efficient, and may even cost less now, as they are smaller, lighter, and have less metal in them.
 
So here's a couple of Enerstar links for some reference material:
http://www.energystar.gov/index.cfm?c=archives.power_supplies
http://www.energystar.gov/ia/partners/product_specs/program_reqs/eps_prog_req.pdf
 
For more information on SWITCHING ac to dc supplies:
http://en.wikipedia.org/wiki/Power_supply#AC.2FDC_supply
 
The Wiki article gives some ideas as to the "magic" that is achieved with the new supplies.
 
If the question was about the LED's themselves and not the transformers/converters that go with them then please excuse my sidetrack.
 
If anyone has seen central DC converters wired throughout the facility I'd be very interested to hear about it.  Certainly many loads are now DC.  Perhaps the Tesla Wars (http://en.wikipedia.org/wiki/War_of_Currents) are swinging back towards Edison for efficiency reasons.
 
Charlie Holleran
Holleran Technologies
scorpdaddy at hotmail.com
 

 

> Date: Fri, 7 Oct 2011 09:27:55 -0500
> From: John.S.Eurek at usace.army.mil
> 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
> secure against interception or modification. Sebesta Blomberg therefore can
> not guarantee that this message has not been modified in transit. This
> message and any files transmitted with it are confidential and intended
> solely for the use of the addressee. If you have received this message in
> error please notify the sender and destroy your copies of the message and any
> attached files.
> 
> 
> 
> 
> 
> 
> 
> 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
> 
> 
> _______________________________________________
> Equest-users mailing list
> http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
> To unsubscribe from this mailing list send a blank message to EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20111007/d9aa9944/attachment-0002.htm>