Using long-term measurements of airflow, electrical power, indoor temperature, and CO ₂ -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 CO 2 -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.

Exploration of HVAC system sizing based on building performance simulation and Monte Carlo method

“…To ensure that the additive model developed produces reasonable results, the peak total cooling loads calculated through EnergyPlus simulation and the 3 There are four levels at orientation: N, E, W, S 4 The window area ratio is the ratio of the window area to the floor area of the perimeter zones 5 Parameters used in model validation only additive model for these 1000 cases were compared. The quality of the developed model was evaluated by mean bias error (MBE), coefficient of variation (CV), and coefficient of determination (R 2 ), as shown in Equations ( 8)- (10).…”

“…Djunaedy et al [2] found that it is not uncommon for systems to be oversized by up to 100%. Right-sized equipment reduces the first cost, extends the life span of equipment and future replacement costs, reduces energy use, and improves occupants' comfort condition [3].…”