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Re: [EnergyPlus_Support] Re: lux and watts



Vincent,

I think you're not getting what Rahul is saying. The Daylighting object outputs a 0 to 1 dimming ratio. That in turn is applied to the the Lights (where you define the wattage) you have defined for your zone.

Best,
Julien

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Julien Marrec, EBCP, BPI MFBA
Ingénieur en efficacité énergétique du bâtiment
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2014-06-19 19:39 GMT+02:00 vincent lacour vlacour@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>:
 

Rahul,
I am sorry to disagree with you.  If in my project we use incandescent bulbs , for a given illuminance I will use five times as much electricity as I would with leds.  This results in: 1/ a higher electricity bill, and 2/  am uch higher heating rate of my light system.  A 1w led will use 1w electricity and produce 0.8 W of heat and 50 lumen.  For the same 50 lumen you need a 5w incandescent bulb which will use 5W electricity and produce 4W heat.

Vincent


On Thu, Jun 19, 2014 at 7:03 PM, rahula7@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
 

There is no need for a lumen/watt ratio for energy modeling. The lighting power input into the lights object is assumed to be sufficient to provide the target illuminance because all the lights would need to be on at night. Thus, when light output = 1 (daylight contribution = 0), the lighting power is also equal to 1. If you use continuous dimming, the min input power fraction and min light output fraction fields will define the relationship between light output and lighting power. If you use stepped dimming, then the number of control steps will determine the lighting power. 


Rahul







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Posted by: Julien Marrec <julien.marrec@xxxxxxxxx>


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