ASHRAE90.1-2010 - Energy Cost Budget Method - Fenestration Orientation

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Hi fellow modelers,

I am working on a compliance energy model for which we are considering the ASHRAE 90.1-2010 Energy Cost Budget (chapter 11) method. Under the budget (baseline) building, section 5 in Table 11.3.1, the instructions refer to the section 5.5.4.5 where the baseline model needs to comply with:

As>=Aw and As>=Ae

As= south oriented vertical fenestration area Aw= west oriented vertical fenestration area Ae= east oriented vertical fenestration area

Our building has As=0. The code says: "If the fenestration area facing west or east of the proposed building exceeds the area limit set in Section 5.5.4.5, the area shall be reduced proportionally until the area is the same as the area limit set in Section 5.5.4.5. The area limit is the fenestration area facing south in the northern hemisphere or the fenestration area facing north in the southern hemisphere as defined in Section 5.5.4.5."

Has anyone dealt with this before? Does this mean that we should assume no windows for east and west sides on this building to comply with this section?

Any thoughts/interpretations would be appreciated.

@nfonner Yes, we did.

There are adjacent buildings on the south plus the scenic view on the north, east and west has probably mandated the glazing on those orientations not on the south.

We are considering the exception with 75% shaded fenestration areas as an alternative but are wondering what would one do if there was no escape from this rule? how should the area on the east and west be reduced PROPORTIONALLY to reach the southern fenestration area given that As=0?

The adjacent buildings to the south would not qualify the project for exception b (buildings that have an existing building or existing permanent infrastructure <20ft to the south... and half as tall as the proposed project.)