Requirements only for exterior lighting?

Only exterior lighting now in v4.

We just realized this as well--how is it acceptable for a fully glazed building to be lit from inside all night long ? This makes no sense whatsoever. My client will be taking advantage of this loophole and we've been left feeling very silly because we assumed that the old requirement to have internal lights turned off was the very essence of this credit. It feels strange to tell the client that this credit makes no sense. 

The requirements for interior lighting controls are addressed under a separate LEED prerequisite (EA Prerequisite: Minimum Energy Performance), which require projects to meet the mandatory requirements of ASHRAE 90.1-2010 or approved equivalent standards.

Per ASHRAE 90.1-2010, Section 9.4.1, automatic lighting shutoff is mandatory for the majority of interior lighting in buildings. Therefore, fully glazed buildings could not be lit from inside all night long, and comply with the requirements of EA Prerequisite: Minimum Energy Performance.

1. ASHARE 90.1-2010 has mandatory control requirements for interior lighting.  (edited to 2010 now)
​    a. Either, All lighting must be automatically shut off within 30 minutes of all occupants leaving the space.
​    b. Or, all lighting shall be off when the space is scheduled to be unoccupied.
​        1. Each space must be independent controls, larger areas shall be no more than 2,500 or 10,000 sf.
​​        2. Manual override can only turn the lights on for 2 hours per activation.

In what way are they taking advantage of the loophole?  Are they planning to claim all spaces are occupied all night?  Are they actually going to be?  Blatantly violating the mandatory control requirements of ASHRAE is not a loophole.  It is a violation.  Don't permit them to violate it.  ASHRAE 90.1 is building code and legally required in most states.

You have described the building as a fully glazed building.  Since the ASHRAE energy budget limits buildings to 40% glazing the envelope is creating a significant energy deficiency.  The MEP systems will have to compensate significantly to reach the energy modeling target.  It does not sound like the energy model matches the intended use of the building.  The lights will have to be off during the night (and HVAC temperature set back) to help with the energy savings in the modeling, but you say they intend to have the lights on all night.

​If the spaces are occupied all night, then yes, the lights in this fully glazed building will be on all night, and allowed by ASHRAE and LEED.  I am finding it difficult to believe a 100% glazed building can meet LEED energy savings if the energy model shows all of these spaces occupied all night.  

Hi Bill--thanks for your comments. In fact its now about 70-75% glazed, and could even reduce further (but not by too much) but shaded extensively externally to reduce energy use and its doing quite well in terms of meeting the energy reduction targets. In addition they're using extremely efficient equipment internally.  Most of one floor + a portion of at least 1 other will operate 24/7--and of course to support this they will probably keep lit the main lobby, entry to parking and service core in order to service the continual occupancy. To be honest, we just found out about this--its quite late in the design sequence-- and have not input it into the model. I thought operating hours had to match in the base building, but I'm not a modeler so I'll check with the team--if base building operation is only day, then it may hurt the outcomes. In any case, this is the "loophole" I was talking about--partial occupancy--so the building will be brightly lit but as long as external lights comply then it can achieve the credit --just seems odd since the reason for the credit is to preserve biodiversity and I fail to see how brightly lit windows don't contribute to light pollution. Further, I just warned the designers that they may find it difficult to ensure that all exterior lighting is compliant considering that they have to keep pathways to the building lit for the shift workers. Still it seems possible.

Yes, the occupied hours need to be equal between the baseline and design models.  One of the ways energy savings is shown is to let the temperature drift further in spaces when they are unoccupied.  A lower delta-T between indoor and outdoor temperatures means less energy loss.  If there are no unoccupied times then this can't happen.

​Generally I don't like glass boxes for reasons unrelated to lighting.  They are energy hogs and will be energy hogs for decades.  It is amazing to me that glass boxes regularly get LEED certified.  

​A typical glass wall will lose 4x more energy than a typical solid wall.  Doing a quick calc for a building.  Same quality of glass and wall.  Only wall ratio changed.
- 100% glazing, the energy loss is 567 kBTU/hr thru the glass.
- 70% glazing, the energy loss is 431 kBTU/hr thru the walls and glass.
​- 40% glazing, the energy loss is 295 kBTU/hr thru the walls and glass.

​This is a significant energy deficit from the glass.  I wonder how much better buildings would perform with a decent envelope.  Or if the envelope could exceed ASHARE as much as the MEP systems.

​The extensive shading only helps reduce solar heat gain in the summer for a few hours a day on the South facing wall.  It doesn't eliminate it, only reduces it.  SHG does not affect the numbers above.