Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
90.1-2010 Table G3.1.5a (Baseline) has two new exceptions regarding the requirement for providing rotational baselines, the first of which appears reasonable/invoked in your situation: If it can be demonstrated to the satisfaction of the Program Evaluator that the building orientation is dictated by site considerations.
That said, "demonstrat[ing] to the satisfaction of the Program Evaluator" seems to invite wiggle room and provides an opportunity for the Program Evaluator to resist for the sake of doing so.
If this exception wasn't provided, I'd defer to rotating the city block. :)
| | 2 | No.2 Revision |
90.1-2010 Table G3.1.5a (Baseline) has two new exceptions regarding the requirement for providing rotational baselines, the first of which appears reasonable/invoked in your situation: If "If it can be demonstrated to the satisfaction of the Program Evaluator that the building orientation is dictated by site considerations.considerations."
That said, "demonstrat[ing] to the satisfaction of the Program Evaluator" seems to invite wiggle room and provides an opportunity for the Program Evaluator to resist for the sake of doing so.
If this exception wasn't provided, I'd defer to rotating the city block. :)
| | 3 | No.3 Revision |
90.1-2010 Table G3.1.5a (Baseline) has two new exceptions regarding the requirement for providing rotational baselines, the first of which appears reasonable/invoked in your situation: "If it can be demonstrated to the satisfaction of the Program Evaluator that the building orientation is dictated by site considerations."
I think since you're latching an addition onto an existing building, this is the kind of site condition(s) referenced in the exception's verbiage.
That said, "demonstrat[ing] to the satisfaction of the Program Evaluator" seems to invite wiggle room and provides an opportunity for the Program Evaluator to resist for the sake of doing so.
If this exception wasn't provided, provided in Table G3.1.5a, I'd defer to rotating the city block. :)
| | 4 | No.4 Revision |
90.1-2010 Table G3.1.5a (Baseline) has two new exceptions regarding the requirement for providing rotational baselines, the first of which appears reasonable/invoked in your situation: "If it can be demonstrated to the satisfaction of the Program Evaluator that the building orientation is dictated by site considerations."
I think since you're latching an addition onto an existing building, this is the kind of site condition(s) referenced in the exception's verbiage.
That said, "demonstrat[ing] to the satisfaction of the Program Evaluator" seems to invite wiggle room and provides an opportunity for the Program Evaluator to resist for the sake of doing so.
If this exception wasn't provided in Table G3.1.5a, I'd defer to rotating the city block. :)
To answer your comment below: I say yes, set any wall area that is common to an existing building as adiabatic (assuming you satisfy items in Table G3.1.2a-d), and yes, include the adiabatic areas in the WWR calc. My reasoning is based on the fact that the language in 90.1-2010 Table G3.1.5c (Baseline) seems resolute: "...gross above-grade wall area". I think your plan East wall would have a max WWR of less than 40% due to adjacent geometry, and your plan South walls and (one) West wall would have a max WWR of zero assuming those adjacent buildings are at least as tall as your addition.
