From Real-Time Monitoring to Active Purification: Nexisense Sensor Solutions Build a Closed-Loop Indoor Air Governance System

In the context of accelerating implementation of building intelligence and healthy building standards, indoor air quality has become a key indicator affecting project acceptance, user satisfaction, and long-term operation and maintenance costs. Pollutants such as formaldehyde (HCHO), PM2.5, TVOC, and carbon dioxide (CO₂) continuously accumulate in confined or semi-confined spaces, with concentrations often 2–5 times or higher than outdoors, directly threatening respiratory health, cardiovascular function, and cognitive performance. Traditional passive air governance relies on manual intervention or timed operation, with delayed response, high energy consumption, and unstable effects, making it difficult to meet the needs of modern green buildings and smart spaces.

The Nexisense indoor air quality sensor series takes high-precision, multi-parameter fusion perception as the core, combining mature detection principles such as laser scattering, electrochemistry, and NDIR infrared, to achieve real-time and stable monitoring of key pollutants, and deeply links with terminal equipment such as fresh air, purification, and air conditioning through standard interfaces, forming a complete closed-loop control system from perception—decision—execution, providing efficient and reliable air quality management solutions for B-end system integrators.

Multi-Parameter Sensor Fusion Perception Technology

Nexisense air quality solutions adopt a modular design, with typical combinations including:

• Laser scattering PM2.5/PM10 sensor: based on Mie scattering principle, detects particles above 0.3μm, range 0–1000μg/m³, accuracy ±10μg/m³ (0–100μg/m³ segment), T90 response<10s, supports continuous sampling and intermittent mode.

• Electrochemical formaldehyde (HCHO) sensor: high-selectivity electrode, detection limit<0.01ppm, range 0–5ppm, response time <60s, built-in temperature and humidity compensation to reduce cross-interference.

• NDIR CO₂ sensor: non-dispersive infrared dual-channel measurement, range 0–5000/10000ppm, resolution 1ppm, accuracy ±(50ppm+3% reading), lifespan >10 years, oxygen-independent.

• MOS multi-gas VOC module: wide-spectrum response to formaldehyde, benzene series, alcohols, smoke, etc. TVOC, Rs/R0 >5 (typical 10ppm target gas), supports digital output and raw resistance value reading.

Each sensor outputs data through a unified protocol (UART/Modbus RTU, I²C), facilitating centralized acquisition and fusion processing by MCU or gateway, enabling multi-pollutant composite index calculation and threshold judgment.

Typical Application Scenarios and System Integration Value

Smart Fresh Air Systems and Heat Recovery Fresh Air Units

Nexisense sensors are embedded in fresh air host return/supply air sections or indoor units as core air quality closed-loop control elements. When PM2.5 >35μg/m³ or CO₂ >1000ppm or TVOC exceeds limit, it triggers variable-frequency fan speed increase, bypass mode or full heat exchange mode, achieving on-demand ventilation, reducing energy consumption while maintaining IAQ compliance, supporting docking with BMS systems.

Central Air Conditioning and VRF Variable Refrigerant Flow Multi-Split Environmental Control

Integrated into return air inlets or indoor unit ducts, real-time monitoring of indoor PM2.5, CO₂, and VOC concentrations, linking DCV (demand-controlled ventilation) logic: CO₂ >800ppm increases fresh air ratio, TVOC exceeding limit elevates purification gear or activates UV sterilization module, compliant with WELL building standards and GB 50346 cleanroom specifications.

Commercial Buildings and Hotel Guest Room Air Management

Multi-point distributed deployment (guest rooms, conference rooms, lobbies), accessing BA systems via RS485 bus or wireless gateway, achieving zoned air quality hierarchical management and energy efficiency optimization. Typical case: hotel guest room sensors detect formaldehyde or CO₂ anomalies, automatically link fresh air/purifier + door access prompt “Do Not Enter” status until safe thresholds are restored.

School Classrooms and Elderly Care Facilities Health Environment Monitoring

Classroom/activity room sensors link fresh air or exhaust when CO₂ >1000ppm, trigger purification linkage and APP push when TVOC or PM2.5 exceeds limit, ensuring respiratory health for children and elderly, supporting integration with smart campus/elderly care platforms for data cloud upload and trend analysis.

Selection Guide: Core Parameters for Matching Project Requirements

• Monitoring Parameter Combination: PM2.5+CO₂ (basic ventilation control) / PM2.5+formaldehyde+TVOC (health purification scenarios) / full parameters (high-end healthy buildings)

• Output Interface: UART (TTL 3.3V/5V, 9600bps) + Modbus RTU (recommended for system integration) / I²C (embedded nodes) / 4–20mA analog (traditional BA compatible)

• Power Supply and Consumption: DC 5V/12–24V wide voltage, average<1W, supports low-power standby mode

• Protection Rating: IP40 (indoor) / IP54/IP65 (duct or humid environments)

• Installation Form: Wall-mounted/embedded/pipeline type / with sampling pump to improve response speed

• Accuracy and Range: PM2.5 0–1000μg/m³ ±10μg/m³; CO₂ 0–5000ppm ±(50ppm+3%); formaldehyde 0–5ppm ±0.03ppm

Recommended system architecture: sensor → MCU/gateway (data fusion and threshold judgment) → terminal equipment (fresh air/purification/air conditioning) → cloud platform (trend analysis and remote management).

System Integration Notes and Best Practices

• Installation Position: Sensor placed at breathing zone height (1.2–1.5m) or return air inlet, avoid direct blowing from outlets and direct impact from pollution sources; ensure airflow representativeness in multi-point deployment

• Power Supply and EMC: Use isolated power supply + filter capacitors, signal lines shielded twisted pair, away from strong electromagnetic sources; good system-level grounding

• Communication and Protocol: Modbus address configurable, polling cycle recommended 5–15s; supports broadcast mode for batch reading

• Calibration and Maintenance: Factory calibrated, recommend clean air zero point + standard gas span verification before project commissioning; re-verification once every 12 months

• Linkage Logic: Recommend graded thresholds + hysteresis control (avoid frequent start/stop), combined with temperature/humidity data for comprehensive judgment

  
  

OEM Customization and Bulk Supply Advantages

Nexisense provides comprehensive customization support for B2B partners:

• Parameter combination, accuracy grading, range adjustment (e.g., extend CO₂ to 10000ppm or TVOC specific gas optimization)

• Output protocol extension (BACnet, KNX, custom frame), pin definition, power supply voltage adaptation

• Shell form (wall-mounted/embedded/pipeline type), protection rating upgrade, explosion-proof optional

• Factory batch calibration report, traceability management, reliability accelerated life testing

• Long-term framework agreement, buffer inventory, fast sample delivery and joint development support

These services help integrators reduce secondary development barriers, stabilize supply chains, and meet different project specifications and certification requirements.

Frequently Asked Questions

1. How does the multi-sensor fusion solution avoid misjudgment actions caused by single-parameter false positives? Uses weighted composite index algorithm (e.g., AQI-like IAQ index), combined with multi-parameter thresholds and hysteresis logic, only triggers high-intensity linkage when 2 or more pollutants exceed limits simultaneously or a single key parameter (e.g., formaldehyde) seriously exceeds limit, significantly reducing false alarm rate.

2. How is long-term stability of sensors ensured in high-humidity or oil fume environments? Electrochemical and laser sensors have built-in temperature/humidity compensation and optical window anti-fouling coating, MOS module optimizes gas-sensitive layer anti-interference formulation; recommend adding pre-filter or regular cleaning, typical 5-year attenuation<15%.

3. What key registers and function codes does the Modbus RTU protocol support? Supports 03 read holding registers, 06 write single register, 16 write multiple registers; key registers include real-time concentration values, IAQ index, status code, temperature/humidity, fault flags, etc., address mapping documentation provides complete definition.

4. How to achieve compatibility with fresh air/purifiers of different brands during system integration? Through standard UART/Modbus output of concentration and alarm status, integrators can develop intermediate gateways or firmware adaptation layers to achieve relay dry contacts, 4–20mA or custom protocol conversion, compatible with mainstream brands (e.g., Yuanda, Panasonic, Honeywell).

5. How to optimize CO₂ sensor response delay in confined spaces? NDIR sensor T90<30s, combined with sampling pump or optimized installation position (near personnel activity areas), can further shorten effective response time; system-level recommend predictive algorithm to advance fresh air ratio adjustment.

6. How to perform field calibration and long-term verification in projects? Recommend using standard gas generator or portable calibrator for zero point (clean air) + span (standard concentration) two-point calibration; re-verification once a year, record drift trend, trigger maintenance when drift >10%.

7. What customization developments are supported to adapt to special building specifications? Customizable monitoring parameter combination, preset alarm thresholds, output protocol (BACnet/IP, KNX), protection rating (IP65+), integrated LoRa/NB-IoT wireless module, etc., development cycle typically 4–12 weeks.

8. How to control total cost of ownership (TCO) for multi-sensor solutions? Through modular design and long-life components (NDIR >10 years, electrochemical >3–5 years), reduce replacement frequency; bulk procurement + custom calibration reduce field debugging workload, typical 5-year TCO reduced by 30–50% compared to traditional multi-sensor solutions.

Conclusion: Partner with Nexisense to Build an Efficient and Reliable Indoor Air Closed-Loop Governance System

Nexisense indoor air quality sensor solutions, with multi-parameter high-precision perception, standard interface compatibility, and deep home appliance linkage capability, provide complete technical support from monitoring to purification for smart fresh air, air purification, HVAC, and commercial building projects. It helps system integrators simplify development processes, enhance system robustness, and significantly reduce project operation and maintenance costs and energy consumption.

Welcome fresh air system integrators, air purification equipment manufacturers, HVAC engineering companies, and smart building solution providers to contact the Nexisense team for detailed technical specification sheets, sample testing support, project case references, or customization development schemes. We look forward to becoming your long-term partner in the field of indoor air quality management, jointly promoting continuous upgrades to healthy buildings and smart spaces.