Date
Inquiry

Our project involves interior fit-out of tenant space in a building of approximately 125,000 gross square feet. The building is mechanically conditioned by two 200 ton rooftop units. One tenant will occupy the entire building. There are 34 rooms in the building that may be occasionally occupied by enough people to be considered "densely occupied" if evaluated on an individual, room-by-room basis. Twenty five (25) rooms range in area from 109 square feet to 112 square feet. One (1) of the rooms is 225 square feet. Eight (8) rooms range from 340 square feet to 2,640 sf. The combined area of the aforementioned rooms totals 8% of the building area, thus the mechanical design team determined that the two units serve spaces that are predominantly not densely occupied. The project goal is to optimize the amount of outside air needed in a space to provide proper ventilation without wasting energy. The Base Building already includes a CO2 sensing and control system with sensors located above the ceiling in the return air plenum. To achieve the intent of the credit, the engineer designing the mechanical systems for the fit-out of the tenant space proposes providing outdoor airflow measurement at each rooftop unit that monitors outdoor air to within 15% of the design minimum outdoor air rate. Does the proposed monitoring and control approach for this situation satisfy the credit criteria? If not, what additional measures would be required to earn the credit?

Ruling

No, the method you are proposing is appropriate for the non-densely occupied spaces only. The credit also details the approach required for densely occupied spaces. All densely occupied spaces, those with a design occupant density greater than or equal to 25 people per 1000 sq. ft. evaluated on a room by room basis (as defined in ASHRAE Standard 62.1-2004) require CO2 monitoring in order to meet the intent of the credit. The monitors shall be between 3 feet and 6 feet above the floor, since sensors in the return plenum indicate average CO2 level, rather than zone CO2 level. Applicable Internationally.

Internationally Applicable
On
Campus Applicable
Off