ASHRAE 62.1 — Section 6.2.5

ASHRAE 170 Table 7-1 / FGI Guidelines 2.1-3.2

This fails on multiple counts. First, ASHRAE 170 Table 7-1 requires a minimum of 12 total ACH in AII rooms — the 10 ACH provided is below the minimum. Second, AII rooms must maintain negative pressure (minimum -0.01 inches w.g.) relative to adjacent spaces, which requires the exhaust rate to exceed the supply rate — not equal it. Neutral pressure provides no directional airflow control and allows infectious aerosols to escape when doors open. Third, while HEPA filtration on the exhaust is good practice, it does not compensate for inadequate air changes or incorrect pressure relationships. The room as designed would not contain airborne pathogens.

ASHRAE 62.1

ASHRAE 62.1 requires outdoor air determined by the ventilation-rate procedure — for offices, 5 CFM per person plus 0.06 CFM per square foot — not an arbitrary fixed percentage. Run the numbers: 20 occupants need 100 CFM of people-OA plus the floor-area component (a 2,000 sq ft zone adds 120 CFM, totaling ~220 CFM). Whether '15% OA' delivers that depends entirely on the unit's supply airflow — a 2,000 CFM unit at 15% provides 300 CFM (passes), a 1,200 CFM unit provides 180 CFM (fails). A percentage setpoint with no calculation behind it isn't a compliant ventilation design.

ASHRAE 62.1 — Section 6.2 (Ventilation Rate Procedure)

Minimum outdoor air position must meet the zone ventilation requirements of the Ventilation Rate Procedure during occupied mode — it can never be 0%. ASHRAE 62.1 ventilation rates apply whenever the space is occupied, so a 0% minimum during occupancy starves the space of required outdoor air and is a code violation. (0% is only acceptable during UNOCCUPIED periods, where ASHRAE 90.1 actually encourages closing the OA damper to save energy.)

ASHRAE 62.1 — Section 6.2.7

The CO2 differential for DCV should be based on the difference between indoor and outdoor CO2 levels, not an absolute 1000 ppm indoor reading. ASHRAE 62.1 Section 6.2.7 allows DCV based on a maximum CO2 differential of approximately 700 ppm above outdoor levels (typically 400 ppm outdoor, so 1100 ppm indoor max). However, a setpoint of '1000 ppm above outdoor ambient' would be 1400 ppm — too high and not compliant. The system logic needs correction.

ASHRAE 62.1 — Ventilation

VAV boxes require an airflow measuring station (sensor ring or averaging pitot tube) to measure actual airflow for proper modulation. Without it, the controller cannot maintain setpoint.

ASHRAE 62.1 / Crestline BAS Specification

This CO2 sensor installation meets all requirements. The 0-2000 ppm range covers the full operating range needed for DCV (outdoor ambient of ~420 ppm to maximum occupied levels around 1000-1200 ppm). The ±30 ppm accuracy meets the specification tolerance. Mounting at 4 feet (breathing zone height) on an interior wall away from supply diffusers and doors ensures the sensor reads representative room air rather than being influenced by drafts or supply air.