Changes Proposed for Standard 90.1

From green roofs to glazing products, measures to increase energy stringencies are being proposed for major sections of ANSI/ASHRAE/IESNA Standard 90.1-2007, Energy Standard for Buildings Except Low-Rise Residential Buildings. Currently, nine proposed addenda to the standard are open for public review.

Proposed addendum by would establish revised lighting power densities for whole-building and space-by-space compliance methods. The addendum would reduce lighting-power allowances in many building and space types while maintaining industry-recommended lighting levels as their basis.

“This will encourage designers to use more efficient lighting technology applications that provide more light without using more energy, which will require more thought at the design phase,” said Eric Richman, chair of the Standard 90.1 lighting subcommittee. “Additional proposed daylighting control requirements will also encourage them to incorporate effective daylighting and corresponding electric lighting control into their designs.”

Changes also are being proposed to the envelope section, including addendum f, which sets requirements for high albedo roofs. This proposal recognizes a number of roof-construction strategies that result in reduced buildings loads.

Other proposed changes to the envelope section are addenda cl and cm, both of which address glazing products. Addendum cl would clarify how to interpret the use of dynamic glazing products that are designed to vary a performance property vs. having just a single value. As the ratings for these products give a range of performance values, designers and code officials require an interpretation on what to use for compliance with the standard. Addendum cm clarifies how to interpret the use of dynamic glazing products given the requirements in proposed addendum bb, which would update building-envelope requirements for opaque elements, such as walls and roofs and fenestration.

In the mechanical section of the standard, proposed addendum ck expands the zone-control demand-control ventilation to include system-level strategies to reduce ventilation during system operation.

The remaining addenda—cg, ch, ci, and cj—would make modeling defined by Section 11 and Appendix G of the standard consistent with other addenda that have modified Sections 6-9. These modifications include daylighting, dual minimum controls, cooling towers, and data centers.

The proposed addenda to Standard 90.1 are available for comment only during their public-review period. The public-review period for addenda ck, cl, and cm ends Feb. 28. The public review period for addenda by, cg, ch, ci, cj, and f ends March 15. To read the addenda or to comment, visit

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