Are ASHRAE 90.1-2010 Appendix G laboratory modeling requirements and/or ASHRAE 90.1-2010 addendum for laboratories allowed for projects using ASHRAE 90.1-2007 Appendix G? If so, should they be required to be used in their entirety (i.e. all ASHRAE 90.1-2010 Appendix G lab requirements without addendum; and/or all 90.1-2010 Appendix G lab requirements with addendum?)
Yes, ASHRAE 90.1-2010 Appendix G laboratory modeling requirements and/or ASHRAE 90.1-2010 addendum for laboratories are allowed for projects using ASHRAE 90.1-2007 Appendix G. Project teams using this option must apply ASHRAE 90.1-2010 addenda in their entirety to laboratory projects.
Additional details regarding ASHRAE 90.1-2010:
• G3.1.2.9.1 Design Air Flow Rates for Baseline System Types 1 - 8, and exception added: "For systems serving laboratory spaces, use a supply-air-to-room-air temperature difference of 17°F or the required ventilation air or makeup air, whichever is greater."
• G3.1.3.13 VAV Minimum Flow Setpoints (Systems 5 and 7)- changed from 0.4 cfm/sf in 2007 to the largest of 30% of zone peak air flow, the min OA flow rate, or the air flow rate required to comply with applicable codes or accreditation standards. And exception to this state:
o Systems serving laboratory spaces shall reduce the exhaust and makeup air volume during unoccupied periods to the largest of 50% of zone peak air flow, the minimum outdoor air flow rate, or the air flow rate required to comply with applicable codes or accreditation standards.
o 90.1-2010 Addendum cn - Exception (d) to G3.1.2.6 Ventilation: "For Baseline systems serving only laboratory spaces that are prohibited from recirculating return air by code or accreditation standards, the Baseline system shall be modeled as 100% outdoor air." This provides credit to proposed design systems that have lower peak design airflow, the Baseline is allowed to vary from the Proposed Case.
o Note, the way this has been treated to date for ASHRAE 90.1-2007 is if cooling loads drive Baseline total supply flow requirements above that of the outdoor airflow supplied in the Proposed Case, Baseline must be modeled with some recirculated air, which is not appropriate for laboratories.
• 90.1-2010 Addendum c - adds the following to the exception to G3.1.1 for Laboratory Systems: "The lab exhaust fan shall be modeled as constant horsepower reflecting constant volume stack discharge with outdoor air bypass."