Method identifying oversizing of mechanical ventilation systems in office buildings using airflow and electrical power measurements

Abstract

Heating, Ventilation and Air-Conditioning engineers face high demands from their clients to deliver reliable, optimized solutions that perform acceptably in terms of energy use and provided comfort. However, time and resources are scarce to deliver an optimized solution. To ensure that the solution works under most operation scenarios, the design is typically based on a combination of conservative rules-of-thumb, general guidelines and a large safety factor. The consequences are building service systems designed for operating conditions that never or very rarely occur leading to oversized systems. The objective of this paper was to propose a method for identifying oversized air-handling units with variable speed drives. It was demonstrated on a case study including six air-handling units in an office building. The method was able to determine that the air-handling units were not grossly oversized or undersized by comparing the measured airflow and SFP from the part- and full-load operation to the design airflow and SFP. However, the method should be extended to include additional performance criterion such as indoor climate and thermal efficiency to be able to conclusively confirm the size of the units.

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

“…). The preliminary study by Khan et al (2019) is an example of how lack of appropriate filtration and correction of airflow measurements produced significantly different results compared to the present case study. Thus, measurements need to be critically evaluated prior use.…”

“…The first limitation was related to the duration of the time period covered by the dataset, which only captured the period from August to October 2019. To investigate the reliability of the used dataset related to airflow and electrical power, the dataset for a two-year period used in the preliminary study by Khan et al (2019) was processed and analyzed according to the method of this paper. Results are presented in Figures 6 and 7.…”

“…Therefore, it can be advised to only extract the bounds needed in tables 2 and 3 and to determine a regression model for the observed SFP n as to compare it to the fitted SFP n using range normalized root mean squared error like in (Khan et al 2019) as to evaluate the performance of AHUs. However, the strength of visual analysis lies on providing a detail view of AHU performance and sizing across a range of loading conditions which can be useful in context of general exploration (Munzner 2014) and evaluation of HVAC performance (Yang and Ergan 2016).…”

Ventilation Study in Achieving Thermal Comfort at Ice Cream Café in Malang City

“…Mechanical ventilation systems in the buildings are intended to supply conditioned air to meet indoor climatic and energy needs [18]. Mechanical ventilation here means that the air in the room is conditioned based on the heat load that occurs in the room using air conditioner (AC) technology.…”

Perspective Chapter: From Data to Design – Leveraging Façade Sensors for Intelligent Architecture

“…These data assist architects in designing spaces that meet their requirements, such as optimising low-occupancy spaces to save energy while still providing sufficient social and seating areas for high occupancy. By identifying unauthorised access or unusual movement patterns, occupancy sensor data can also help improve building security [3].…”