An Emergy-based Approach to Evaluate the Effectiveness of Integrating IoT-based Sensing Systems into Smart Buildings

Abstract

Wireless Sensing Systems based on the Internet of Things (IoT) are increasingly being deployed in smart buildings to reduce their energy consumption and environmental impacts. However, the actual environmental costs of integrating IoT-based sensing systems into smart buildings have rarely been considered when reporting on their overall sustainability footprint. This paper presents an Emergy-based methodological approach to ascertain the effectiveness of integrating IoT-based sensing systems into smart buildings. The proposed method employs three novel Emergy Neutrality Indices (ENIs): The Sensing System to Building Emergy (SBEm) ratio, the Emergy Neutrality Score (EmN), and the Emergy Payback Time (EmPBT). The Solar House at Gainesville, Florida, retrofitted with an IoT-based sensing system, is used as an example building for computing these indices. A Building Energy Model (BEM) is created using the EnergyPlusTM simulation engine available in DesignBuilder V7 to determine the operational Emergy of the building. A custom-built CO2 sensor is used to collect the real-time occupancy data for incorporation into the BEM. The Emergy Neutrality computation demonstrates that the integration of the given sensing system is effective in the Solar House, with SBEm, EmN, and EmPBT values of 2.06E-03, 0.28, and 3.61 years, respectively. By varying the sensors’ energy-savings potential and spatio-functional configurations, nine design scenarios are generated and evaluated for their environmental performance using Emergy ratios and the proposed ENIs. Finally, the Solar House is compared with the Rinker Hall to emphasise the significance of reporting these indices. In the future, designers, architects, and other stakeholders could use these ENIs as useful sustainability assessment tools to evaluate the environmental effectiveness of integrating these smart sensing systems into buildings.