Parking garage exhaust ventilation

Hello,

We are working on a  New Construction office building.

The garage  within the building consists of two identical underground floors.

According to ASHRAE 62.1-2010, this would require 3.7 l/s/m², equating to approximately 46,628 l/s or ~168,000 m³/h of continuous exhaust airflow.

 However, we would like to justify a reduction in this value based on local practices, advanced vehicle standards, and the use of a demand-controlled ventilation (DCV) strategy.

 Key Justifications:

1. Updated Vehicle Emissions Context
   The majority of vehicles expected to use the garage comply with Euro 6 and Euro 7 emission standards, which significantly reduce pollutants. Additionally, the project includes the installation of at least 90 electric vehicle (EV) charging stations, further lowering expected emissions.
2. Local and European Standards
   The design complies with EN 15251 and VDI 2053 (2014-12 Part 1) – “Air Conditioning – Car Parks – Exhaust Ventilation” – a widely accepted German standard. Based on these, the required exhaust airflow is approximately 84,000 m³/h, nearly half of the ASHRAE-prescribed rate. Reference: VDI 2053 Standard
3. Demand-Controlled Ventilation (DCV)
   The garage ventilation will be controlled using carbon monoxide (CO) sensors placed throughout the space. Based on real-time CO readings:
   • Ventilation rates will be modulated at low, medium, or high levels.
   • In case of elevated CO levels in a specific zone, that area’s exhaust system will increase to full capacity, and the system will temporarily reach or exceed ASHRAE 62.1-2010 values at that local level.
4. Contaminant Monitoring & Exposure Limits
   • The system is designed to maintain CO levels below 35 ppm (8-hour TWA) and never exceed 50 ppm at any time, in accordance with local and international health guidelines.
   • Other potential pollutants, including NO₂, VOCs, and particulates, have also been considered, though their expected concentrations remain minimal due to the high EV ratio and modern combustion technology.
5. Energy Efficiency Considerations
   Designing the garage for full ASHRAE exhaust rates continuously would result in significant over-sizing, increased energy use, and reduced HVAC system efficiency, which would contradict LEED's energy efficiency goals.

 Please let us know if any additional documentation or calculations are required for the acceptance of this credit?