IES-VE User Forum

Hi,

I've got a query regarding parasitic power i was hoping you may be able to assist me with.

Under photoelectric options we have two options "control type" and "sensor type".

Does the parasitic power associated with the "sensor type" (i.e. standalone or addressable) still apply if i select "switching" as the "control type".

Meaning, am i paying a penalty on parasitic power if im selecting "switching".

My thoughts behind it is that there are no sensors associated with a system that is switching.

I found the following statement from "top tips for achieving compliance" online about achieving compliance which said the following.

"Care should be taken when assigning dimming controls to zones. If a user sets applies controls dimming
controls globally to each zone in the model then internal zones and zones without any windows will
still pay the penalty of parasitic power but will not benefit from any reduced lighting load."

The above statement suggests to me that we pay a penalty for "dimming" but not "switching".

Maybe my understanding is wrong and hoping for someone to share some light on this.

Regards

The photoelectric options apply to rooms where daylight harvesting is applicable. It should not be selected where there is only manual or occupancy control.

Under the photoelectric options:
The switching control mechanism turns a light off completely as daylight levels reach the required level.

The dimming control mechanism gradually reduces the light output as daylight level increase to the required level.

Both of the control types require a daylight sensor to determine the amount of daylight available and therefore parasitic power applies to both.

If I have understood the scenario you are trying to describe correctly you do not have any form of daylight control and therefore photoelectric options should be unticked. i.e. neither daylight switching or daylight dimming and no associated parasitic power.

Does this help?

Just a thought.

I've a feeling the "switching" control type means that there is still a sensor associated with the lighting but instead of the light dimming it now switching off.

If this is the case then i still only have two parasitic power associated with the "control type". standalone and addressable.

If this is the case then what is the purpose of having the option for "switching" and "dimming" if they both can have the same "sensor type" parasitic power associated with it, i.e. 0.3w/m2 for standalone and 0.57w/m2 for addressable.

Meaning what effect does "swithcing" or "dimming" have on results if any.

Correct me if im wrong

Regards

dimming saves more energy as it starts reducing the output from a light earlier than switching.

i.e if part of the lighting requirement is met by daylight, dimming would reduce the output from a light to meet the remaining requirement. Reducing further as daylight levels increase untill all of the requirement is met by daylight and the light turns off.

using switching the light remains on fullly until all of the lighting requirement is met by daylight, at this point the light turns off.

excellent.

Thats fully cleared it up.

Much Appreciated.

thanks for the prompt reply.

Just one final question.

Lets say we have both occupancy sensing and photoelectric selected.

Are we doubling up on parasitic power or does one overide the other.

regards

yes i believe they are added together

therefore if you have one sensor doing both jobs I put half the parasitic power in each box