ID#2406 made on
EQc5 - Indoor chemical & pollutant source control
LEED BD+C: New Construction, LEED BD+C: Schools, LEED ID+C: Commercial Interiors, LEED BD+C: Core and Shell
This CIR is in reference to the ventilation design of the 2 level underground parking garage (16,070 m2 / 172975 sq.ft) in an high-rise office building and its compliance with the requirements of Cred...
This CIR is in reference to the ventilation design of the 2 level underground parking garage (16,070 m2 / 172975 sq.ft) in an high-rise office building and its compliance with the requirements of Credit EQc5. The project is located in Frankfurt/Main, Germany. The exhaust fans of the parking garage are demand-controlled, depending on the CO content in the garage and start operating when the CO content exceeds the following levels: - Level 1: CO content > 30ppm => 4 m3/m2*h (0.22 cfm/sq.ft) - Level 2: CO content > 50ppm => 8 m3/m2*h (0.44 cfm/sq.ft) - Level 3: CO content > 80ppm => 16 m3/m2*h (0.88 cfm/sq.ft) If the CO content exceeds 80ppm, an alarm will sound and signs require drivers to turn off their cars immediately. In addition to the exhaust fans of the parking garage, jet fans are installed throughout the parking garage to ensure the efficient ventilation of the garage. They are operated locally, depending on where the CO content exceeds the threshold. The garage is directly exhausted to the outside without recirculation. The required pressure difference to adjacent spaces (aver. 5Pa / min. 1Pa) can be achieved in all Levels with the exhaust rate as specified above. The rooms connected to the garage will have a positive pressure, to ensure the required pressure difference between the garage and adjacent rooms when the exhaust fans of the garage are not operating. Additionally, all of the stair cases and elevator rooms are separated by a vestibule from the garage to prevent the entry of pollutants into the building. The CO content read out is averaged over a period of 15 minutes. In total appr. 45 CO measuring devices will be installed in the 16,070 m2 parking garage at a height of 1.5m. As required by LEED, all rooms connected to the parking garage are equipped with self closing doors and deck to deck partitions. MERV 13 filter are installed in the air supply system to regularly occupied spaces and permanent entryway systems are installed in all entryways. Outside air and return air from offices and storage rooms is provided as supply air to the garage. Despite the fact that the exhaust rate is not as required by LEED at least 0.5 cfm/sq.ft., the project team believes that the intent to minimize exposure of building occupants to potentially hazardous gases from the garage is fulfilled, due to the following measures: a. It is assured that the CO content does not reach harmful levels, due to the demand controlled ventilation system. b. The thresholds, as described above, are very strict, e.g. the New York City Building Code, Title 27 / Subchapter 7 specifies: ". max. average concentration of 100ppm for periods longer than 1 hour and with a maximum concentration at any time of 400ppm". c. Local jet fans provide an immediate improvement of the air quality by diluting the CO content locally. d. Vestibules with doors on each side separate the garage from the hallways leading to the stair cases and elevators. e. Hallways leading to the stair cases and elevators and a small number of storage rooms will be provided with positive pressure in relation to the garage. Please advice if the projects teams suggested approach for the ventilation of the parking garage is acceptable for the USGBC to fulfill the requirements of this credit.
The proposed strategy appears to satisfy the requirements of the credit, as well as EQ prerequisite 1. The project is using a demand control ventilation strategy that is capable of providing a maximum exhaust flowrate of 0.88 cfm/sf, which is significantly greater than the 0.5 cfm/sf requirement in the LEED-NC v2.2 Reference Guide, and greater than the 0.75 cfm/sf requirement in ASHRAE Standard 62.1. The project team is not required to provide a constant 0.5 cfm/sf exhaust rate, if demand control strategies with sufficient sensors and controls capable of maintaining acceptable carbon monoxide concentration set points have been provided. The proposed carbon monoxide set points, however, are too high. The sensors need to be distributed throughout the garage, including those places with the highest anticipated vehicular traffic and the lowest exhaust ventilation rate, and the controls set to maintain a maximum carbon monoxide concentration of 20 ppm at each sensor location. In addition, an audible alarm must be activated should the concentration of carbon monoxide at any sensor location exceed 35 ppm. These carbon monoxide concentrations are to be the instantaneous concentration or the average over no more than one minute. (This assumes that this project site is not a high altitude location (i.e. more than 4,500 feet above sea level). For high altitude locations the set points for carbon monoxide must be reduced to 13 ppm with an alarm point at 23 ppm to account for the reduced mass concentration of oxygen at these altitudes.) The project team has also demonstrated that the pressurization requirements can be met on a continuous basis. Applicable Internationally.
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