Clarification is requested for energy modeling protocol on a lab building which is 44,000 sf in area. An energy model was done based on Laboratory Modeling Guidelines using ASHRAE 90.1-2004 Appendix G. (http://www.epa.gov/lab21gov/pdf/ashrae_appg_draft_508.pdf). In previous CIRs (5/11/2005) earlier versions of these guidelines have been accepted in creating Baseline building models, except for calculating fan energies. Also, LEED for Laboratories Application Guide (Draft) states that the guideline may be used for energy modeling purposes. The project team, however, recently came across a CIR ruling dated 3/4/2008 that these guidelines may not be used. We would like to confirm: 1. If the Laboratory Modeling Guidelines using ASHRAE 90.1-2004 Appendix G can be used to create the Baseline building model for our project? If not: 2. Per CIRs dated 11/3/2006 and 2/26/2007, the Baseline system should be representative of a typical system. Since Systems 3 & 4 (ASHRAE90.1 Table G3.1.1A) would not be suitable for a lab with 100% outside air requirements in Houston,TX, can we use System 5? 3. Per CIR dated 8/13/2007, can we use a min. flow ratio of 50% for our baseline-supply and baseline-exhaust, both? 4. Per CIRs dated 12/21/2004,2/4/2004,12/15/03(EAp2) fume hoods should be treated as process loads. In our project, it would be impossible to isolate the energy from these as they are synchronized with the supply VAV boxes, and are occupancy driven. In this context, they aid in modulating outdoor air levels and comfort ranges for occupants and hence cannot be treated as process loads. Can we let the fan energy associated with exhaust be part of overall ventilation energy? 5. Equipment power density for lab areas is taken at 8.0W/sf in both Proposed and Baseline models, referring to the typical value from Laboratories for the 21 Century:Energy Analysis. Is this acceptable?
This CIR is asking several questions. The responses are: Question 1: No, the project may not use Labs21 to create the Baseline, as stated in the referenced CIR ruling dated 3/4/2008: "Project teams may not use the Labs21 "Laboratory Modeling Guidelines using ASHRAE 90.1-2004 Appendix G" as a compliance path for modeling laboratories. The deficiencies in modeling laboratories are being addressed through addenda to ASHRAE 90.1-2004. Project teams are permitted to use addenda to ASHRAE standards as outlined in a USGBC Memo posted here: http://www.usgbc.org/ShowFile.aspx?DocumentID=2664". Question 2: The applicant is requesting a different system be used than the one prescribed by the ASHRAE Appendix G. As per the CIR rulings dated 11/3/2006 and 2/26/2007 that were referenced above, the system prescribed in Appendix G must be used as the baseline. It is unclear why System 3 or 4 would not be suitable for the lab building as mentioned in the CIR. Please note that the ASHRAE 90.1-2004 Standard Appendix G modeling protocol is not a compliance method but rather a method of comparing the proposed design\'s energy performance to a building that would have been typically built Question 3: The applicant is requesting clarification of minimum turndown ratios for the baseline system. The baseline laboratory exhaust only may be set as 50%, the supply and non laboratory exhaust systems must meet the requirements of Appendix G, as the referenced CIR dated 8/13/2007 states: Section 6.6.7.2 of Standard 90.1-2004 requires the proposed laboratory system to include either VAV controls that are capable of reducing exhaust and makeup air volume by 50% of design values or heat recovery meeting the requirements of Section 6.5.6.1. This is consistent with the applicants request to not include heat recovery in the baseline building model. In addition, the baseline VAV system serving the laboratory should only reduce the exhaust and makeup air volume to 50% of design values during unoccupied periods instead of the minimum volume setpoint of 0.4 cfm/ft2 of floor area as required by Section G3.1.3.13." Question 4: The applicant is requesting clarification on how to account for fume hood operation. If the flow through the fume hoods is required to operate the building HVAC systems as designed, then they should be considered part of the HVAC system. If the fume hoods are operated in a way that is in addition to the required air-flow and ventilation air from the HVAC system, then they should be considered process loads. Question 5: The applicant is requesting acceptance of equipment power densities. Equipment power densities should be modeled in a way that best represents the designed equipment load in the building. If no more specific information is available for the project, the Labs21 baseline would seem to be a good guideline to use.