Dear All,
To benefit from a lighting power reduction, our project is proposing installing push-button switches in the communal stairs.
I know that in ASHRAE Appendix G, table G3.2 allows for a 10% reduction of LPD if an occupancy sensor is installed.
However, what about push button switches which turn the light on for, let's say, 30 seconds once pushed? I think these provide exactly the same savings as occupancy sensors.
Do you think these will be accepted in lieu of occupancy sensors?
Thanks,
Omar
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
January 14, 2013 - 10:39 am
You will need to provide justification for any savings claimed. This could include any studies showing savings or perhaps acceptance in a utility rebate program.
Anthony Hardman
Building Performance AnalystThe Green Engineer
16 thumbs up
January 14, 2013 - 11:08 am
If the default position is off, I think these would be acceptable. In the grand scheme of things, it's not going to have a big impact if it just applies to stairwells anyway.
Maya Karkour
EcoConsulting872 thumbs up
January 14, 2013 - 6:42 pm
Thanks Marcus & Anthony,
But the issue is: if the USGBC accepts occupancy sensors which turn the lights on for 30 seconds whenever someone moves in the stairwell, they should also accept a push button (default position is OFF) which, when pushed manually, turns on the light for 30 seconds too.
Note that the proposed scenario's lighting power densities can be reduced by 10% if occupancy sensors are installed. I'm assuming it's the same scenario for push-buttons.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
January 14, 2013 - 7:16 pm
The 10% credit for occupancy sensors is based on numerous studies. The majority of time in a regularly occupied space the lights are on. The majority of the time I would assume the stairwell lighting would be off. You may be able to make the case that claiming a 10% credit in this case is conservative but since it is an unusual situation you will need to make the case. I would recommend you provide a narrative and justify the savings as I stated earlier.
One issue this has is that at least a portion of the control is manual and in general projects cannot claim savings for manual controls. Just explain how and why you modeled it to eliminate any questions in the reviewer's mind.