[Bldg-sim] Car Parking Ventilation Fans

Sherif Farag sherif.sabr at gmail.com
Thu Dec 18 09:04:32 PST 2014

Dear Modellers;

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

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

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

b)    b)f the answer is YES, can I assume the saving is 45%

I will appreciate your feedback


*Sherif Farag*

*Sustainability Consultant*

P.O. Box: 127842

Abu Dhabi, UAE

M: +971 55 199 0022 | E: sherif.sabr at gmail.com | Skype ID: sherif.farag9
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