ANSI Opens Public Comment Period for ASHRAE 189.1 Addendum “ag” Changes

The American National Standards Institute (ANSI) has opened a public comment period for recommended changes to several addendums to ASHRAE Standard 189.1-2011, “Standard for the Design of High-Performance Green Buildings (Except Low-Residential Buildings).”

Among the proposed changes are some within Addendum “ag” to define “daylight area” as the “area in an enclosed space that is in the primary sidelighted area, daylight area under roof monitors or daylight area under skylights.”

“This addendum updates definitions by referencing ANSI/ASHRAE/IES Standard 90.1-2010, Energy Standard for Buildings Except Low-Rise Residential Buildings,” writes ASHRAE in its description of the changes.

For the definitions of “daylight area under roof monitors” and “daylight area under skylights,” the proposal suggests that ASHRAE 189.1 now reference ASHRAE 90.1 for these definitions.

The proposal seeks to remove the following definition of the primary sidelighted area:

“The total primary sidelighted area is the combined primary sidelighted area without double-counting overlapping areas. The floor area for each primary sidelighted area is directly adjacent to vertical fenestration in exterior wall with an area equal to the product of the primary sidelighted area width and the primary sidelighted area depth. The primary sidelighted area width is the width of the window plus, on each side, the smallest of:

  1. 2 ft. (0.6 m); or
  2. The distance to any 60 in. (1.5 m) or higher vertical obstruction.

The primary sidelighted area depth is the horizontal distance perpendicular to the

glazing which is the smallest of:

1. The distance from the floor to the top of the glazing; or

2. The distance to any 60 in (1.5 m) or higher vertical obstruction.”

The proposal also seeks to remove the following definition of “the total daylight area under skylights:”

The total daylight area under skylights is the combined daylight area without double-counting overlapping areas. The daylight area under skylights is bounded by the skylight opening, plus horizontally in each direction, the smallest of:

  1. 70 percent of the ceiling height [0.7 × CH];
  2. The distance to any daylight area under roof monitors; or
  3. The distance to the front face of any vertical obstruction where any part of the obstruction is farther away from the nearest edge of the skylight opening than 70 percent of the distance between the top of the obstruction and the ceiling.”

Comments on the changes are due on April 28 and can be sent to Bert Etheredge at 404/636-8400 or by email to

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