Canadian Consulting Engineer

ASHRAE proposing changes for ventilation and energy saving standards

October 9, 2007
By Canadian Consulting Engineer

The American Society of Heating Refrigerating and Air-Conditioning Engineers (ASHRAE) is proposing new requirements...

The American Society of Heating Refrigerating and Air-Conditioning Engineers (ASHRAE) is proposing new requirements for demand-controlled ventilation in commercial and institutional buildings. The changes are being proposed for ANSI/ASHRAE Standard 62.1-2007, “Ventilation for Acceptable Indoor Air Quality.” Some proposed changes to the standard are open for public review and comment until October 14, but most are open until October 29.
One of the changes is addendum “g” specifying more precise requirements for demand controlled ventilation (DCV) based on the use of carbon dioxide levels as they relate to outdoor airflows. Such controls allow for the alteration of outdoor air intakes based on time of day and predictable schedules. The addendum would require that optional DCV controls provide no less than the “area outdoor air rate” listed in Table 6-1. It would also require that such controls ensure that the minimum outdoor air intake flow dips no lower than the required exhaust airflow rate. Other addenda proposed for standard 62.1 affect such things as performance-based air cleaning requirements and the recirculation of air from energy recovery systems being transferred to washrooms.
Also set for changes is ASHRAE Standard 90.1, a standard that addresses energy efficiency. Among the changes being proposed for ANSI/ASHRAE/IESNA Standard 90.1 “Energy Standard for Buildings Except Low-Rise Residential Buildings,” is addendum “l” to add requirements for closed circuit cooling towers to reduce their energy consumption. The addendum would add minimum efficiency and certification requirements for axial and centrifugal fan closed circuit cooling towers, also known as fluid coolers.
Another change to 90.1 is addendum “n” which extends variable air volume (VAV) fan requirements to large single-zone units, whereas currently VAV fan control is only required for multiple-zone systems. The change would take effect in 2012 after equipment manufacturers have had time to redesign their products. Most of the addenda to 90.1 are also up for public review and comment until October 29.
For a full list of the addenda to both standards and to comment, see


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