Fan power limitation requirements for complex HVAC systems, such as those in hospitals and laboratories, would be improved under a proposed change to ASHRAE’s energy standard. Eight proposed addenda to ANSI/ASHRAE/IESNA Standard 90.1-2004, Energy Standard for Buildings Except Low-Rise Residential Buildings, are open for public comment until May 1, while two are available until April 16. Included is addendum ac, which would expand application coverage to address complex mechanical systems.
“The standard would more effectively address static pressure associated with complex HVAC systems requiring specialized equipment in return air or exhaust air systems, such as those in hospitals,” says Larry Kouma, who heads the group that oversaw the proposed addendum. “Appropriate allowances for discharge and return air flow treatment equipment would be allowed, enabling a clear avenue for these systems to demonstrate compliance using the prescriptive compliance methods of the standard. Or, if required, users can still use the standard’s energy cost budget method.”
The addendum also improves compliance consistency and strengthens stringency for simple systems with an easy-to-use format and structure. Other proposed addenda open for comment until May 1 are:
- Addendum aa adds definitions for lighting-related terms.
- Addendum ab clarifies which sections should be referenced in Section 11 and Appendix G.
- Addendum ae changes Section 11 and Appendix G to clarify the way lighting power is to be modeled.
- Addendum ai revises the lighting power requirements to eliminate confusion.
- Addendum aj adds the ASTM test method E 1980 - Standard Practice for Calculating Solar Reflectance Index of Horizontal and Low-Sloped Opaque Surfaces.
- Addendum al clarifies the terminology for metal building roofs and the required assembly U-factors for such roofs.
- Addendum am allows minimum variable air volume turndown to be limited by the minimum ventilation requirement for a zone.
Two proposed addenda to Standard 90.1 are open for review until April 16. They are:
- Addendum ag clarifies that only HVAC fans that provide outdoor air for ventilation need to be modeled as running continuously.
- Addendum ah clarifies the budget building model heat recovery requirement by stating that condenser heat recovery must be included in the budget building model if it is a prescriptive requirement for the building.
To obtain drafts of (or comment on) proposed addenda aa, ab, ac, ae, ag, ah, ai, aj, al, and am, visit (www.ashrae.org/standards). The standard provides minimum requirements for the energy-efficient design of buildings except low-rise residential buildings.
This information was reprinted with permission from the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), an international organization of 55,000 persons. Its sole objective is to advance through research, standards writing, publishing, and continuing education the arts and sciences of heating, ventilation, air-conditioning, and refrigeration (HVAC&R) to serve humanity and promote a sustainable world. To find out more, visit (www.ashrae.org).
