[Bldg-sim] Natural ventilation

[July Chen]

Ground Source Heat Pump - heating modeDear colleague:

      I have met a serious problem during LEED a factory.
        
      For this project, There equipped some HL-600G&HL-600 Gravity type skylight ventilator on the factory roof and some operable window at the surrounding walls. But the height of the ventilator is from 10.5m to 13m over the ground surface.

            LEED/ASHRAE 62 requirment: Natural ventilation spaces shall be permanently open to and within 8m of operable wall or roof opening to the outdoors.   

           Assume the breathing zone is 1.6m high, So LEED accept height of the ventilator should be lower than 9.6(1.6+8)m. So the interior area(more than 8 m away from surrounding walls) does not have valid natural ventalition system as described by LEED/ASHRAE.

     
           The designer does not agree our opinion, their reason:

1.    the design is to give comfort to the operators on the floor since the process equipment is very hot and the space within the 8-m high will get unbearably hot.  Nanjing is known for its hot summers
2.    the specification is for 22 air changes per hour (ACPH) and the need for 8-m floor to roof eave height is to aid natural draught ventilation so it is easier to reach 22 ACPH
3.    The supplier is to warrant 22 ACPH and provide ASHRAE calculations to reach this figure.
4.    It is less acceptable to fill the roof area with mechanical roof ventilators since it is energy dependent (an increase in the carbon footprint) and as such agaist the LEED concept
5.    The approach is within the philosophy of LEED in that the operators comfort and well being is at the heart of this design, the use on natural ventilation address sustainable design in that no energy is required to get 22 ACPH.

    QUESTION:  1. Are the designers reason will be agreed by LEED?

                2.  If we installed some exhaust fan on the roof, makeup air will go in through operable windows on the surrounding walls. whether the ventalition system changed to mechanical ventalition system as defined by ASHRAE/LEED?

 Any further suggestion is highly appreciated. 


Ziqiang Chen
 
Project Engineer
 
EMSI
 
86-21-54962727 TEL
 
86-21-64435767 FAX
 
zqchen at emsi-green.com.cn
 
www.emsi-green.com
 

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