Using low-cost IEQ sensors to improve HVAC efficiency and reduce operational carbon

The decarbonization of the built environment increasingly depends on the effective operation of HVAC systems that balance energy efficiency with occupant health and comfort. Continuous monitoring of Indoor Environmental Quality (IEQ) parameters is essential for demand-driven ventilation, optimized HVAC control, and reduced operational carbon emissions. However, conventional IEQ and Indoor Air Quality (IAQ) monitoring systems are often costly, proprietary, and difficult to deploy at scale, limiting their applicability in existing buildings and non-critical infrastructure.

This work presents the development and initial evaluation of a low-cost, modular, real-time IEQ monitoring platform based on Micro-Electro-Mechanical Systems (MEMS) sensors integrated with an Arduino MKR1010 microcontroller. The system measures parameters directly relevant to HVAC performance and control, including temperature, relative humidity, volatile organic compounds (VOCs), particulate matter (PM2.5), ambient noise, and lighting levels. Emphasis is placed on open-source architecture, modular sensor integration, and affordability, enabling scalable deployment across multiple indoor zones.

Calibration against commercial reference instruments was conducted to validate data reliability. The prototype was deployed in occupied indoor environments, including office and laboratory spaces, to assess performance under both stable and highly dynamic operational conditions. Results demonstrate that the system successfully captures variations associated with occupancy, equipment use, and HVAC operational cycles, providing actionable insights into ventilation adequacy and indoor pollutant dynamics.

The findings indicate that low-cost IEQ monitoring can support data-driven HVAC strategies such as demand-controlled ventilation, early fault detection, and performance benchmarking, contributing to reduced energy use and associated carbon emissions. By lowering the economic and technical barriers to continuous IEQ monitoring, the proposed system offers a practical pathway for integrating real-time environmental feedback into HVAC operation. This approach aligns with ASHRAE’s objectives for energy-efficient, low-carbon buildings and highlights the role of accessible sensing technologies in supporting sustainable HVAC design and operation