I assume the Standard must be followed when the User’s Manual contradicts it.
90.1 – 2010, Standard
9.4.1.3 (b) “….reduce lighting power of each luminaire by a minimum of 30% when there is no activity for no more than 30 minutes.”
90.1 – 2010, User’s Manual
9.4.1.3 (b) “….reduce lighting power to 70% or less of maximum when there is no activity for 30 minutes or longer.”
The Standard requires auto-control to reduce light power at 30 minutes or before.
The User’s Manual requires auto-control to reduce light power after 30 minutes.
Waleed AlGhamdi
Sustainability EnablerEskew+Dumez+Ripple
18 thumbs up
July 1, 2020 - 5:33 pm
Intereseting. I always understood it to be a 30 minute max vacancy, even though in practice I've seen it around 15 minutes or thereabouts. In the 90.1 2016 User Manual, the langugae was clarified a bit and reads "... the lighting power of a space must be automatically reduced to less than 50% of the full power within 20 minutes of the last occupant leaving the space."
Standard 90.1 2016 reads "... The general lighting power in the space shall be automatically reduced by at least 50% within 20 minutes of all occupants leaving the space."
Ignoring the change in reduction amount and vacancy duration, the language of the standard and user manual align better in 2016.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
July 2, 2020 - 9:29 am
My guess is that the users manual in this case is clarifying very confusing language in the standard. What is written in the standard actually does not make any sense. You could interpret that as 10 seconds which would be ridiculous. The users manual makes more sense to me and I would go by that instead of the standard in this case. As Waleed points out you can often look to more recent versions of the standard to gain clarification and in this case it is pretty clear what is intended relative to these controls.
Dave Hubka
Practice Leader - SustainabilityEUA
LEEDuser Expert
494 thumbs up
July 2, 2020 - 10:04 am
To provide a bit of background.....I came across this language because GBCI triggered a review comment based on the User's Manual langauge...which was inconsistent with the languge in the Standard.
The project's lighting design incorporates auto-control to reduce lighting power to less than 70% of full power when 20 minutes of no motion (no occupancy) is detected.
We got this figured out,,,,,just a bit of a pickle when GBCI / Standards are inconsistent and/or incorrect.