Our project has 4 basements with fresh air, exhaust and circulation fans. The logic of exhaust fan functioning is designed such that during normal mode only few fans operate, during pollution mode few more fans additionally switches on. CO sensors are installed to monitor and control the fan operation. Can we take benefit for this logic in exceptional calculations as per the guidelines outlined in advanced energy modelling guide appendix (Like a dual speed fan)?
If yes, the baseline has to be defined for 0.75 Cfm/sft and 0.3W/cfm as per ASHRAE. But these values are only for the exhaust fans in normal mode alone. (Please correct if the understanding is wrong). Then how to take benefit of the logic defined to save energy?. Also how to do the exceptional calculations for the fresh air and circulation fans running in dual speed mode?
Thank you !
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
November 20, 2014 - 10:11 am
Sounds like these basements are parking garages? If not where is the CO coming from? If it is CO sensor control of ventilation (and this is not standard practice in the area of the project) then yes you can claim the savings.
Per LEED Interpretation 10371, the project team must demonstrate that the proposed design goes beyond standard practice and this measure must be modeled as an Exceptional Calculation Measure (ECM). In order for approval, the following conditions must be met. Address each of the following:
a. Baseline case shall meet the requirements of ASHRAE 90.1-2010, Section 6.4.3.4.5 Enclosed Parking Garage Ventilation. Baseline fan volume shall be based on the minimum required ASHRAE 62.1 parking ventilation rates of 0.75 cfm/square foot. Baseline system fan power shall be calculated at 0.3 watts per CFM.
b. Proposed case shall reflect the actual design. Evidence shall be provided documenting that demand control ventilation strategies are sufficient to automatically detect contaminant levels of concern in parking garages (Carbon Monoxide, Particulates, VOCs, etc. and NO2) and modulate airflow such that contaminant levels are maintained below specified contaminant concentration as identified in ASHRAE 62.1-2010 Addendum d. Evidence shall also be provided that contaminant sensors are placed in space in an appropriate manner for detection of contaminant in question and that the sensors be calibrated yearly.
c. If other activities occur in the garage area, the ventilation for these uses shall be in addition to garage vehicle ventilation.
d. Proposed case shall be modeled such that a minimum air flow of 0.05 cfm/square foot is maintained.
e. A narrative shall describe all Baseline and Proposed case assumptions included for this measure, and the calculation methodology used to determine the projected savings. The narrative and energy savings should be reported separately from the other efficiency measures in the LEED Form.
f. No more than a 75% fan energy savings shall be claimed for this measure.
Chilufya Lombe
Sustainability ConsultantSolid Green Consulting
30 thumbs up
November 20, 2014 - 10:22 am
Hi Marcus, this response answers a question I asked round about the same time. Please ignore my query when you get to it.
Rathnashree Bharadwaj
4 thumbs up
November 21, 2014 - 4:39 am
Hi Marcus, Thanks for the reply.
Yes, the basement is used for parking only.
Is the fan power of 0.3 W/cfm defined as per 62.1 is only for the exhaust fans or includes fresh air fans as well?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
November 21, 2014 - 9:47 am
That is the total baseline fan power - 0.3 W/cfm of maximum supply airflow.