The CO and CO2 monitoring project at Lillie Square Car Park addresses ongoing air quality challenges within this high-traffic underground parking facility in London. Fire alarms have often been triggered by high carbon monoxide levels. This is mainly due to the large number of vehicles parked, especially supercars with high emissions. On-site engineers and building managers identified these issues and commissioned Envirologik to install multiple advanced sensors across the car park. These sensors continuously monitor CO and CO2 concentration levels, providing critical data to analyse emission patterns and develop effective mitigation strategies to improve safety and air quality throughout the facility.

Implications of the CO and CO2 Monitoring Project

CO2 emissions in car parks present significant challenges, particularly in enclosed or poorly ventilated areas. These emissions impact air quality, human health, environmental sustainability, and regulatory compliance. The primary source of CO2 in car parks is vehicle emissions from internal combustion engine (ICE) vehicles. This occurs when cars are idling, parking, or manoeuvring. Congestion and idling exacerbate CO2 concentration as vehicles wait for spaces or exit the car park. Additionally, ventilation systems that rely on electric fans can indirectly contribute to CO2 emissions if powered by fossil-fuel-based electricity. Effective management of these emissions is crucial for maintaining safe air quality and adhering to regulations.

CO2 Concentration and Health Risks

While CO2 itself is not highly toxic at normal levels, elevated concentrations indicate poor ventilation and the potential presence of harmful gases like CO and NOx. Typical health thresholds include:

• 400–1,000 ppm: Normal outdoor levels

• 1,000–2,000 ppm: Poor air quality, potential drowsiness

• 2,000–5,000+ ppm: Headaches, sleepiness, concentration loss
  Mechanical ventilation or natural airflow in car parks usually keeps CO2 below 1,000 ppm.

Environmental Impact

CO2 emissions from car parks contribute to the site’s overall carbon footprint. Large parking facilities, such as those in shopping centres or airports, can notably affect urban heat and air quality. CO2 combines with other pollutants, escalating issues in densely populated cities.

Regulations and Mitigation Measures

Regulatory requirements vary but often mandate minimum ventilation rates (e.g., 6–10 air changes per hour), installation of CO/CO2 sensors to control fans, and energy-efficient systems to minimise indirect emissions.

Execution of the CO and CO2 Monitoring Project

Envirologik has installed six CO and CO2 sensors in critical areas of the car park, provided by Polyteck, to monitor emissions and identify problem spots for risk mitigation. These sensors collect parts per million (ppm) data that engineers analyse to develop strategies for improving air quality and preventing issues before they escalate.

The sensors used are YO Pure Pro devices, which measure a comprehensive range of indoor environmental conditions: particulate matter (PM2.5, PM4, PM10), carbon monoxide (CO), carbon dioxide (CO2), total volatile organic compounds (TVOC), atmospheric pressure, illumination, temperature, humidity, and noise levels. Powered by USB-C, external power supplies, or Li-Ion 18650 batteries, they communicate wirelessly via LoRaWAN with secure data transmission through membership in the LoRa Alliance.

Key features include:

• Nine precise environmental sensors pre-calibrated during production

• CO and CO2 sensors specifically designed to avoid cross-reactivity with other gases

• MCERTS-certified PM2.5 measurement

• Easy mounting and low energy consumption

This setup enables continuous, reliable monitoring of the car park’s air quality, supporting proactive management and compliance with health and safety standards.

Data collected over a 90-days period has provided valuable insights, clearly indicating the reasons behind the consistent fire alarm activations. Notably, the zone at Bay 10/11 has been identified as the primary source of recurring alarms. The detailed data gathered from this area, shown below in accompanying diagrams, highlights the elevated levels of CO and CO2 responsible for triggering the alarms consistently.