Rating System

LEED ID+C: Commercial Interiors

Rating System Version

v2 - LEED 2.0

Inquiry

The requirement to achieve this credit for a mechanically ventilated space is to increase outdoor air ventilation rates by at least 30% above the minimum rates required by ASHRAE 62.1-2004. We would like to know if the outdoor air ventilation rates shall be maintain under all conditions or if it could be decreased according to the demand (as per article 6.2.7 of ASHRAE 62.1-2004). We would like to propose to our client the installation of CO2 sensors to modulate the outdoor ventilation rate according to the occupation of spaces, but we are not sure if it will compromise EQ Credit 2. The following example shows how we could keep the outdoor air ventilation rate 30% above the minimum rate but also to allow a reduction according to the needs. The design airflow of the example according to ASHRAE 62.1-2004 is 3825 CFM. Usually, the CO2 concentration shall remain under 1000 PPM. But if the CO2 sensor reads 750 PPM, the airflow may be reduced to 2260. In our case, the design airflow will be 4975 CFM (30% over ASHRAE), and if the CO2 sensor reads 750 PPM, the outdoor airflow will be 2940 CFM (30% over 2260 CFM). Therefore, the airflow will always be 30% above the standard. Is it acceptable to design a system this way according to the EQ Credit 2?