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21 Changes to Standard 90.1 Proposed

Twenty-one addenda proposed for ANSI/ASHRAE/IESNA Standard 90.1-2007, Energy Standard for Buildings Except Low-Rise Residential Buildings, are open for public review.

Standard 90.1 provides minimum requirements for the energy-efficient design of buildings except low-rise residential buildings. The proposed addenda cover a range of topics, including daylighting, air leakage, energy-efficiency-ratio (EER) and integrated-energy-efficiency-ratio (IEER) values, and requirements for variable-refrigerant-flow (VRF) air conditioners and heat pumps.

If no comments are received on the addenda, they likely will be incorporated into the 2010 version of the standard slated to be published this fall. If comments are received, the substance and volume of those comments will determine whether they are incorporated into the 2010 standard.

Among the proposed addenda are two that deal with daylighting. Addendum cu would address the “night lights” that are part of an emergency system when no occupants are in a space. Addendum ct would reduce the threshold for daylighting to 250 sq ft from 1,000 sq ft.

In another area, Addendum bu would modify computer-room efficiency requirements based on comments from an earlier public review.

The proposed addenda are:

Public Reviews from March 5-April 4:
• Addendum bb would modify appendices C and A in response to comments received on the previous version of the addendum, which modifies all fenestration and opaque assembly requirements in the standard.
• Addendum bf would place performance requirements for air leakage of the opaque envelope. Performance requirements have existed on fenestration and door products to date, but evidence suggests that the opaque envelope is the source of the majority of air leakage in buildings caused by lack of attention in the design, construction, and enforcement processes, which in turn is caused by the absence of performance criteria.
• Addendum bz addresses the comments received during the first public review calling for clarification of the requirements to reduce misinterpretation on the proposed monitoring requirements.
• Addendum ce would clarify requirements and avoid conflicts with other existing requirements for lighting space control.
• Addendum cs originated with a continuous-maintenance proposal to address information received on Addendum bs on receptacles after the public-review period closed and that the committee found to have merit.
• Addendum cu would control the “night lights” that are part of an emergency system when no occupants are in a space. This has definite energy savings and is not prohibited by electrical codes.
• Addendum cv would add energy-efficiency requirements for service water-pressure booster systems.
• Addendum cw would address corrections and clarifications necessary to Section 11, Table 11.3.1, Service Hot Water Systems.
• Addendum cx would allow a 40-percent window-wall area path within prescriptive Tables 5.5-1 through 5.5-8.
• Addendum cz would incorporate bi-level control for parking garages to reduce wasted energy associated with unoccupied periods for many garages and allow an exception for lighting in the transition (entrance/exit) areas to accommodate Illuminating Engineering Society (IES) recommendations.
• Addendum da would establish that an Appendix G baseline will be based on the minimum ventilation requirements required by local codes or a rating authority and not proposed design ventilation rates.
• Addendum dc. The conditions and common practice that existed to create the need for this requirement on tandem wiring are no longer practiced primarily with the new federal efficacy requirements and products available on the market.

Public Reviews from March 5-April 19:
• Addendum bu would modify the computer-room efficiency requirements based on comments received during the first public review.
• Addendum cd would strengthen language to require exterior control rather than just require control capability; add bi-level control for general all-night applications, such as parking lots, to reduce lighting when not needed; and add control for façade and landscaping lighting not needed after midnight.
• Addendum cn would add two versions of a combined advanced control to the control incentives table. These control-system combinations involve personal workstation control and workstation-specific occupancy sensors for open office applications. The control incentive will apply only to the particular controls when they are applied in open office areas.
• Addendum co would make three major amendments to Table 6.8.1A: update EER and IEER values for all condensing units and water as well as evaporatively cooled air conditioners with cooling capacities greater than 65,000 Btuh, establish a separate product class for evaporatively cooled air conditioners with different energy-efficiency standards, replace the integrated-part-load-value (IPLV) descriptor for condensing units with the new IEER metric, and amend the EER with more stringent values.
• Addendum cp would establish, for the first time in Standard 90.1, efficiency requirements for VRF air conditioners and heat pumps, including heat pumps that use a water source for heat rejection.
• Addendum cq would modify the duct-sealing requirements in Standard 90.1.
• Addendum cr would set a definition for an unmet load hour currently lacking a throttling range or limit to the set point. It was decided that the baseline and proposed will have the same thermostat-throttling range. This required additional language in the unmet load-hour definition as to how throttling range effects determination of an unmet hour along with additional language in Table 11.3.1 and Table G3.1, Design Model.
• Addendum ct would reduce the threshold for daylighting from 1,000 sq ft to 250 sq ft.
• Addendum cy would make several revisions to the economizer requirements in Section 6.5.1 and Section 6.3.2.

The proposed addenda to Standard 90.1 are available for comment only during their public review period. To read the addenda or to comment, visit

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