ASHRAE standard news
Fourteen proposed addenda to the standard currently are open for public comment. Under proposed addendum l, closed circuit cooling tower requirements to help reduce energy consumption would be added to the standard. The addendum would add minimum efficiency and certification requirements for both axial and centrifugal fan closed circuit cooling towers, also known as fluid coolers.
“These requirements will provide consulting engineers, system designers and contractors with guidelines for the selection of independently certified, energy-efficient closed circuit cooling towers,” Mick Schwedler, chair of the 90.1 committee, said. “This change also will complement existing minimum and certification requirements for open circuit cooling towers, helping prevent confusion between the requirements for open vs. closed.”
Also open for public comment is addendum n, which extends fan requirements for large single-zone units. VAV fan control currently is required in the standard for multiple-zone systems. Extending VAV control to single-zone units would save energy by reducing fan energy consumption when space cooling loads are reduced, he said.
The change would take effect in 2012, allowing air conditioning unit manufacturers time to redesign and test their units. Manufacturers are currently redesigning to meet the 2010 phase-out of certain refrigerants
“Utility rebate programs and other incentives should encourage wider demand for these units and help this requirement to see real savings before 2012,” he said. In addition, addendum r, which would change informative Appendix G’s performance rating method into a normative appendix, is open for comment. Making the performance rating method normative, or required, would allow its adoption into advanced energy standards, such as proposed Standard 189P, Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential Buildings, being developed by ASHRAE in conjunction with the Illuminating Engineering Society of North America and the U.S. Green Building Council. Additionally, language has been changed to make Appendix G enforceable allowing adoption by model codes.
Requirements for systems that use optional demand-controlled ventilation strategies are being proposed for ASHRAE’s ventilation standard. ANSI/ASHRAE Standard 62.1-2007, Ventilation for Acceptable Indoor Air Quality, sets minimum ventilation rates and other requirements for commercial and institutional buildings.
Seven proposed addenda to the standard currently were open for public comment until late October 2007.
Currently, the dynamic reset section of the standard allows designers to use optional controls to reset outdoor air intake flow and/or zone minimum airflow as conditions within the system change. For instance, it would allow a ventilation-system control approach that alters outdoor air intake flow based on time-of-day, if variations in zone population follow a predictable schedule, according to Dennis Stanke, committee chair.
Proposed addendum 62g provides more specific requirements for such optional system controls, especially those historically called “demand controlled ventilation” (DCV) and based on the use of CO2 levels, as they relate to outdoor airflow rates.
For example, the addendum would require that optional DCV controls provide no less than the “area outdoor air rate” listed in Table 6-1, and that such controls maintain the minimum outdoor air intake flow no lower than the exhaust airflow rate required by Section 6.2.8, Stanke said.
“After public review and approval, this change should clarify DCV requirements,” he said.
Also open for public comment is proposed addendum 62.1c, which would add performance-based air cleaning requirements to section 6 of the standard. This would allow designers in jurisdictions outside of the United States to more readily determine when air cleaning is required. If approved, this addendum also would add air cleaning requirements for systems in non-attainment areas for particulate matter with diameter 2.5 microns (PM2.5)and smaller. Such systems would need to use intake air filters with minimum efficiency reporting value (MERV) 11.
“Through better filtration, this would improve indoor air quality in many metropolitan areas of the United States,” Stanke said.
Also open for public comment is addendum 62.1i, which replaces mandatory language requiring that outdoor air rates for environmental tobacco smoke (ETS) areas be determined using engineered methods with language indicating that increased outdoor air rates address odor and comfort for ETS areas, but not health. It also expands and clarifies a note to inform designers that increased outdoor airflow has not been shown to reduce health effects associated with ETS.