ATLANTA - The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has announced that public input to help shape the technical requirements in Standard 90.1 is being sought through 21 proposed addenda, which could become part of the 2010 version of the standard.

ANSI/ASHRAE/IESNA Standard 90.1-2007, Energy Standard for Buildings Except Low-Rise Residential Buildings, provides minimum requirements for the energy-efficient design of buildings except low-rise residential buildings. The proposed addenda cover a range of topic areas, including daylighting, air leakage, EER and IEER values, and requirements for VRF air conditioners and heat pumps.

“Our goal is to produce a standard to increase energy efficiency in buildings,” said Mick Schwedler, Standard 90.1 committee chair. “Public input from the industry into development of the standard has proven invaluable since it was first published 35 years ago.”

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, said ASHRAE. 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 control the “night lights” that are part of the emergency system when there are no occupants in the space. Today, generally by default, lights are kept on even if buildings are unoccupied. Therefore, there are savings to shut them off. Addendum ct would reduce the threshold for daylighting to 250 square feet from 1,000 square feet.

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

“The 90.1 committee worked closely with manufacturers, designers, and owners of computer rooms to address comments and produce the language in this addendum,” said Drake Erbe, Mechanical Subcommittee chair.

Below is a list of proposed addenda open for public review until April 4:

• Addendum bb – would modify Appendix C and Appendix 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 process due to 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 the 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 which the committee found to have merit.

• Addendum cu – would control the “night lights” that are part of the emergency system when there are no occupants in the space. This offers definite energy savings and is not prohibited by the electrical codes.

• Addendum cv – would add energy efficiency requirements for service water pressure booster systems.

• Addendum cw – would address corrections and clarification necessary to Section 11, Table 11.3.1 section 11 Service Hot Water Systems.

• Addendum cx – would allow a 40 percent window wall area path within the prescriptive Tables 5.5-1 through 5.5-8.

• Addendum cz – would incorporates bi-level control for parking garages to reduce the wasted energy associated with unoccupied periods for many garages and allows an exception for lighting in the transition (entrance/exit) areas to accommodate IES recommendations.

• Addendum da – would establish that an Appendix G baseline shall be based on the minimum ventilation requirements required by local codes or a rating authority and not the 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.

The following proposed addenda are open for public review until April 19:

• Addendum bu – would modify the computer room efficiency requirements based on comments received during the first public review.

• Addendum cd – would strengthen the language to actually require exterior control rather than just require the 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 and 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; and replace the IPLV descriptor for condensing units with the new IEER metric and amend the EERs 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 90.1.

• Addendum cr – would set a definition for an unmet load hour currently lacking a throttling range or limit to the setpoint. It was decided that the baseline and proposed shall 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 sections.

• Addendum ct – would reduce the threshold for daylighting from 1,000 square feet to 250 square feet.

• Addendum cy – would makes several revisions to the economizer requirements in section 6.5.1 and in section 6.3.2

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

Publication date:03/22/2010