Using long-term measurements of airflow, electrical power, indoor temperature, and CO2-concentration for evaluating sizing and performance of an all-air HVAC system in an office building - a case study

Abstract

Monitoring performance of heating, ventilation, and air-conditioning (HVAC) during building operation enables to evaluate the appropriateness of the system’s design. Such insights can help to reduce energy consumption while ensuring satisfying indoor conditions in the monitored building. Additionally, such insight can help to improve future HVAC design. The aim of this paper is to present a case study demonstrating how HVAC engineers can evaluate whether the monitored air-handling units (AHUs) were appropriately sized and performed as intended based on design requirements regarding energy-efficiency, thermal conditions, and indoor air quality (IAQ). Three months of measurements of airflow, electrical power, indoor temperature, and CO2-concentrations were collected from an office building with six AHUs. The results showed that three of the AHUs were appropriately sized and satisfied the thermal condition, IAQ and energy-efficiency requirements. The remaining three AHUs were apparently appropriately sized and satisfied IAQ requirements, but they did not satisfy the required energy-efficiency and thermal conditions. The applied approach seemed to be suitable for supporting building operating managers for on-going performance monitoring as it was able to identify discrepancies from intended performance. But it remains the task for the operating personnel to identify the cause of the identified discrepancies.