Indoor Air Quality Monitoring for Indian Buildings — ASHRAE 62.1 + WELL v2 + IGBC + NABH
By MEPVAULT Editorial Team · MEP Consultant · HVAC / Sustainability · 11 May 2026
Reading time ~ 9 min · Originally published: 05 May 2026 · Last revised: 11 May 2026
For a 30,000 m² Delhi office in November, outdoor PM2.5 routinely exceeds 200 µg/m³. WELL v2 Air demands indoor ≤ 12 µg/m³ on 24-hour average. The gap is closed by 93 ceiling-mounted CO₂ + PM2.5/10 + TVOC + T/RH sensor packs feeding BACnet/IP to the BMS, driving DCV + PM-spike response + TVOC flush logic. Capex ₹19 lakh — picks up max WELL Air points + IGBC EQ-2 + AHRI compliance.
Why IAQ monitoring matters for Indian commercial + healthcare
For a 30,000 m² office in Delhi during November (post-monsoon, pre-winter when ambient PM2.5 exceeds 200 µg/m³), the gap between outdoor and indoor air quality determines whether occupants get sick. ASHRAE 62.1-2022, WELL v2, IGBC EQ-2, and NABH HIC.6 all set thresholds — and a real-time monitoring stack lets the BMS respond before complaints reach HR.
What to monitor + where
| Parameter | ASHRAE 62.1 threshold | WELL v2 threshold | Sensor type + accuracy | Indian sensor cost ₹/point |
|---|---|---|---|---|
| CO₂ | ≤ outdoor + 700 ppm | ≤ 800 ppm peak | NDIR ± 30 ppm | 12,000-18,000 |
| PM2.5 | ≤ 15 µg/m³ (24-hr avg) | ≤ 12 µg/m³ | Laser scattering ± 10 % | 22,000-35,000 |
| PM10 | ≤ 50 µg/m³ | ≤ 35 µg/m³ | Laser scattering ± 10 % | same sensor as PM2.5 |
| TVOC | ≤ 500 µg/m³ | ≤ 500 µg/m³ | MOS or PID ± 15 % | 18,000-28,000 |
| Formaldehyde (HCHO) | — | ≤ 27 µg/m³ | Electrochemical ± 20 % | 25,000-40,000 |
| Ozone (O₃) | — | ≤ 100 µg/m³ | Electrochemical ± 15 % | 22,000-35,000 |
| Radon (where applicable) | ≤ 4 pCi/L | same | Alpha track + electronic | 30,000-45,000 |
| Temperature + RH | 22-26 °C, 30-60 % | same | RTD + capacitive | 3,000-5,000 |
A 30,000 m² Delhi office — IAQ monitoring stack architecture
| Zone type | Sensor density | Total sensors | Capex (₹ lakh) | BMS integration |
|---|---|---|---|---|
| Open office (300 m² avg) | 1 sensor pack / zone | 60 | 12.5 | BACnet/IP |
| Conference rooms (15 nos) | 1 sensor pack each | 15 | 3.2 | BACnet/IP |
| Cabin offices (40 nos) | grouped (1 per 4 cabins) | 10 | 1.8 | BACnet/IP |
| Corridors + circulation | 1 per floor at AHU return | 6 | 0.9 | BACnet/IP |
| Outdoor reference | 2 (one per OA intake) | 2 | 0.6 | MQTT to cloud |
| Total | — | 93 | 19.0 | — |
Sensor pack = CO₂ + PM2.5/10 + TVOC + T/RH in a single ceiling-mounted unit. The cumulative capex on this 30,000 m² office runs ₹19 lakh for 93 sensor points + BMS integration. Sounds high, but the building delivers WELL v2 Air score 8 points (max) + IGBC EQ-2 max + AHRI 1230 IAQ compliance — material for a Platinum-tier sustainability submission worth ₹30-50 Cr in building valuation.
Control loop integration — what BMS does with the data
- DCV (Demand-Controlled Ventilation) — modulate AHU OA damper from 0.5 ACH minimum to 4 ACH based on CO₂ trend. Saves ~22 % cooling energy in low-occupancy periods.
- PM2.5 spike response — when outdoor PM2.5 > 100 µg/m³, BMS lowers OA fraction to 10 % + increases recirculation. Indoor PM2.5 stays < 25 µg/m³ even when Delhi outdoor hits 400 µg/m³.
- TVOC alarm + ventilation purge — > 500 µg/m³ triggers 30-minute 100 %-OA flush. Standard during deep-cleaning chemical use.
- Trend logging + monthly reports — IAQ dashboard for facility manager + WELL re-certification + IGBC operations data. Five-year archival.
- Alert thresholds + escalation — yellow at 80 % of code threshold, red at 100 %. Auto-email to facility manager + WhatsApp on red.
What goes wrong on Indian projects — three patterns we audit every quarter
- Sensors over-specified at concept stage (every cabin gets one) then 50 % deleted at value engineering. Result: zones with no IAQ data. Fix: design sensor density at zone level not room level.
- BMS integration paid for but never commissioned — sensors stream MQTT, but no DCV setpoint logic written. Indoor CO₂ stays at 1,100 ppm because there is no control loop. Always include commissioning + 90-day tuning in the BoQ.
- Outdoor reference sensor placed inside the building shaft — measures plenum air, not actual ambient. Place outdoor sensor on a north-facing façade or rooftop weather mast.
References
- ASHRAE Standard 62.1-2022 — Ventilation for Acceptable Indoor Air Quality (§6 IAQ Procedure), ASHRAE Atlanta.
- WELL Building Standard v2 — Air Concept Features 01-04, International WELL Building Institute 2024.
- IGBC Green New Buildings v3.0 — EQ-2 Indoor Environmental Quality Monitoring.
- NABH Accreditation Standards 5th Edition — HIC.6 Hospital Infection Control (IAQ requirements).
- ISO 16000-29:2014 — Indoor Air — Test Methods for VOCs and Aldehydes.
- ASTM D6245-18 — Standard Guide for Using Indoor CO₂ Concentrations.
- CPCB National Air Quality Index — Indian National AQI methodology + thresholds.
- EPA IAQ Building Education and Assessment Model (I-BEAM) 2008.
// About the Authors
MEPVAULT Editorial Team — A team of practising MEP consultants based in India. ISHRAE-affiliated; FSAI-aligned.