Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

90.1-20XX ECB - Exterior Lighting

asked 2016-08-17 15:54:08 -0500

updated 2016-08-17 20:06:07 -0500

I am seeking clarification on the inclusion/exclusion of exterior lighting when completing an ECM/Chapter 11 model. The language is similar between all of my 2007, 2010, 2013; for both the 90.1 Standard(s) and accompanying User's Manual(s). Is exterior lighting included?

NO: The User's manual specifically calls out to exclude exterior lighting. Our/my assumption is that exterior lighting falls in Section 9.4, making it a mandatory item, though that doesn't fully explain why it couldn't be traded-off. The User Manual documentation forms also do not include a separate 'exterior lighting' category.

YES: In the Standard, Table 11.3.1 Part 12 Misc Loads talks about exterior lighting, indicating that "all end uses must be accounted for" - though it mentions nothing of the Baseline Exterior Lighting Allowances or trade-offs. It actually calls for Baseline=Proposed. 'Part 6 Lighting' from the table also makes no real explicit language on exterior lighting either.

For Appendix G (not ECM) it is known/thought that exterior lighting is included in the models, though reviewing this section has left me searching for the inclusion of 'all' exterior lighting, and not just "parking garage and Façade" lighting. The User Manual explicitly calls out to include Exterior, but I cant seem to find that in the Standard.

What are others' experiences or thoughts? Code references appreciated. Thanks.

edit retag flag offensive close merge delete

2 Answers

Sort by » oldest newest most voted

answered 2016-09-13 00:17:31 -0500

What an interesting question! Short answer -- it doesn't really matter what we think, it only matters what your code reviewers think, and how they interpret it.

I think it is probably more correct to model it identically in the baseline and proposed (because of the "include all loads" language), but my local jurisdiction seems to prefer it broken out with baseline vs proposed since that is what they are used to under IECC Total Building Performance Method (where it is explicitly included and traded). They want to see that the design of the exterior lighting is in compliance.

Since compliance is the name of the game, I always show a baseline and proposed load generated using 9.4. I haven't had a project that is close enough to the edge that a bit of exterior lighting tradeoff makes a difference, and code officials are happy.

edit flag offensive delete link more

answered 2016-09-09 08:44:07 -0500

In Table 11.3.1, Part 12 Miscellaneous Loads, on both the proposed and budget sides, in 90.1-2007, 90.1-2010, and 90.1-2013 says:

All end-use load components within and associated with the building shall be modeled, unless specifically excluded by Sections 13 and 14 of Table 11.3.1: including, but not limited to, exhaust fans, parking garage ventilation fans, exterior building lighting, swimming pool heaters and pumps, elevators and escalators, refrigeration equipment, and cooking equipment.

Which indicates that you should not include exterior lighting in the model for either the budget or proposed models.

This is just my individual interpretation.

edit flag offensive delete link more


thank you for an answer!

but a follow-up question: exterior lighting is not mentioned in sections 13 or 14, and with the wording above it would seem to indicate that it should be modeled since it is not explicitly excluded....? Where am I missing the "not / must exclude"...? it seems like the wording goes out of its way to be inclusive of all loads ("not limited to"), and all of the other elements in that list are included in models (parking garage fans, elevators, etc).....color me confused...sorry if I'm being dim...

dradair's avatar dradair  ( 2016-09-09 09:16:16 -0500 )edit

I would agree that it is not the clearest wording but the "including ... exterior building lighting" seems specific to me. Although ultimately, it does not matter since even if you include exterior building lighting in the proposed design since there is not explicit budget defined for it, it would be modeled as the same in the proposed and budget. For Section 11, which is just looking to make sure the design energy cost does not exceed the energy cost budget, adding the same amount of energy to both does not impact compliance.

JasonGlazer's avatar JasonGlazer  ( 2016-09-09 09:38:54 -0500 )edit

I agree that you don't have to include exterior lighting, but for a different reason. If you take out the exception language, Table 11.3.1, Part 12 reads:

All end-use load components within and associated with the building shall be modeled: including, but not limited to, ..., exterior building lighting, ....

But if you look at Section 13 the exception says:

a. component energy usage does not affect the energy usage of the systems and components that are being considered for trade-off.

Ext lighting wont affect any systems within the building that are considered for trade-off

rraustad's avatar rraustad  ( 2016-09-09 09:47:57 -0500 )edit

I agree with the verbiage...but it appears indicates inclusion of exterior lighting, not excluding it. Similar to how exhaust fans or parking garage fans are included. Exterior lighting is the only element on this list that is not included on the ECB reporting forms.

If exterior lighting were included, would it not follow the limits prescribed in Section 9.4? Similar to how fan power limitations for exhaust fans? ECM is checking against a "prescriptive" building. This could make it a credit or a penalty depending on the design.

dradair's avatar dradair  ( 2016-09-09 10:09:17 -0500 )edit

and don't get me wrong - I have typically excluded exterior lighting from ECB models, but in diving in and reviewing the language; I'm struggling to find an explicitly stated "exterior shall not be included" except from the User Manual (this is not code). The exception rraustad points out is another avenue discussed internally, but exterior lighting comes through the electrical meter, which can impact the rates for electrical....its part of the proposed building design; credit or penalty should reflect a total design.

dradair's avatar dradair  ( 2016-09-09 10:14:38 -0500 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools

1 follower


Asked: 2016-08-17 15:54:08 -0500

Seen: 244 times

Last updated: Sep 13 '16