[Bldg-sim] Car Parking Ventilation Fans
nathanm at rushingco.com
Thu Dec 18 10:14:29 PST 2014
I think you’ve presented a reasonable approach to an exceptional calculation, if you can establish it as reasonable that the fans would operate full-bore 24/7 otherwise. Does the garage have 24/7 access? If not, the reviewer might decide that it would be standard practice to have a time clock shut-down the fans during off-hours, and only allow credit for turning down the fans during hours of normal operation.
As a point of reference, for multifamily high-rise projects with parking garages, the Energy Star Multifamily High-Rise Simulation Guidelines- https://www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/mfhr/ENERGY%20STAR%20MFHR%20Simulation%20Guidelines_Version_1%200_Rev03.pdf?f027-c6f2 (Hey look everybody, they’ve just released the Jan 2015 version!), state :
For example, reduced fan runtime from installing CO sensors in residential associated garages may be modeled using 8.4 hr/day fan runtime in Proposed Design,
compared to 24 hr/day runtime in the Baseline Building Design. If Demand Control Ventilation is modeled in the Proposed Design, the baseline ventilation CFM must be
based on the lesser of the design ventilation flow rates required by the applicable code and the actual specified flow rate.
So for that kind of parking garage application it is reasonable to claim ~65% fan reduction.
I’ve had this exceptional calculation rejected on LEED projects where the CO control is required by local code, because the reviewer stated that it is thus standard practice, and not worthy of an exceptional calculation. I always found that unreasonable, as it punishes a project that happens to have a more strict local code, where as a similar building located elsewhere could receive the credit for the same measure.
Nathan Miller, PE, LEED AP BD+C – Mechanical Engineer/Senior Energy Analyst
RUSHING | D 206-788-4577 | O 206-285-7100
From: Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sherif Farag
Sent: Thursday, December 18, 2014 12:05 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Car Parking Ventilation Fans
I am modelling a residential building with underground car park, the car parking will be mechanically ventilated via variable speed fans using ducted ventilation system to provide an air-change rate comply with ASHRAE 62.1-2007. Pollutant sensors (PS) are connected to BMS to control fans speed at parking floors to achieve ventilation recommended by ASHRAE 62.1.
Pollutant sensors locations and numbers have been determined to ensure that no part of the car park is located more than 25 meters from a sampling point, monitoring locations selected are considered worst-case within the car park area. And that each area which is serviced by a separate ventilation system has a separate monitoring point. In addition, one sampling point is provided at each of the entrances and exits of the car park. The monitoring will take place within the breathing zone between 1 and 1.8m above the floor and more than 0.1 m from walls or air conditioning equipment.
Based on the occupancy schedule of the project, it is assumed that the number of vehicles moving in the parking area will be minimal between 8:00 pm to 8:00 am, this means that the CO levels in this period will be less than 50 ppm -given the large parking areas and small number of cars using the garage during these hours- and based on the sequence of operation for this system, the fan speed will be reduced at least 50% for 12 hour.
The sequence of operation of this system will be as the following:
a) Less than 25ppm, fan speed will be 1.5 ACH
b) At 25ppm, fan speed will be 3 ACH
c) Between 25ppm to 50 ppm, Fan speed will be 3 ACH to 6 ACH
d) At 50ppm, fan speed will be 6 ACH
Feedback CO sensors will reduce the fan speed by at least 50% for 12 hours a day and hence the energy consumption will be reduced by at least 45% a day.
My questions are:
1) a) Does the above sounds as an exceptional calculation (For me it is not standard practice and therefore can be done as an exceptional calculation)
b) b)f the answer is YES, can I assume the saving is 45%
I will appreciate your feedback
P.O. Box: 127842
Abu Dhabi, UAE
M: +971 55 199 0022 | E: sherif.sabr at gmail.com<mailto:sherif.sabr at gmail.com> | Skype ID: sherif.farag9
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