Re: [EnergyPlus_Support] daylight

Although the language implies as much, in this point I don't think it differs from the normal daylighting calc. Although there are differences in how effectively lighting types make light flux at certain input wattages, "dimming" assumes a linear power to flux reduction which may be more similar to switching off groups of lights. The aspect of the light emmiter becomming less efficient at lower dim settings is not yet part of energyplus. Furthermore, modern dim controls+lights are "electronic" and not "resistive" as in the past. Basically the drop in efficiency may be negligable. Otherthan this, I guess you could account for the "losses" by defining other OtherEquipment objects and driving them with an EMS program. What does the manufacturer data say for the lighting you are trying to model?

2015-12-16 15:40 GMT+01:00 Fakeha Sehar fakeha_s@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>:

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how about the daylight:DElight controls, does this object exactly maintain daylight plus electric light lux to the set point value for low daylight levels?

On Wednesday, December 16, 2015 3:37 AM, "Jean Marais jeannieboef@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

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My understanding is that the control is quite crued. I don't think a convertion of lighting power to lux exists in the algorithms because we don't define it anywhere in the lighting object. If it does it will be pretty generic.

So basically it's just a "stupid" proportional (or step if defined) control to reduce lighting power based on lux delivered by daylight.

On 16 Dec 2015 6:32 am, "Fakeha Sehar fakeha_s@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

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the daylight:controls module dims light as per the set point lux but does it dim the lights to the extent that the total daylight plus electric light lux is exactly equal to the set point value in the case when daylight illuminance is low? or just dims so that the daylight plus electric illuminance together produces lux near set point value? Does the lux measured at the photosensor location indicate that in the entire controlled zone the same lux level is being maintained?

Anyone experienced in daylighting control: If the zone is around 49m in length and 4m deep would one photosensor be effective, placed at the center of the zone, to control electric lights? When I place two photosensors (each controlling 50% f the zone space) along the length or depth of the zone, the savings decrease as compared to using only one photosensor. The lights are never completely shut down even if the daylight lux is greater than set point value.