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繁體中文Reducing HVAC Fan Energy in a Manufacturing Workshop: A Practical Upgrade Story
07/15/2026Energy projects sometimes focus on chillers while leaving air movement unchanged. In many facilities, however, supply and exhaust fans operate for long periods and continue at high speed even when demand has fallen. A retrofit delivered by AISA PACIFIC SHENGRUI LIMITED for a large manufacturing workshop illustrates how better fan selection and control can address this hidden load.
The first step was not to select a new fan. It was to understand how the existing equipment was being used. Manufacturing workshops often combine high-pressure local exhaust with high-volume general ventilation. Selecting only by motor rating, without a system curve, can result in inadequate airflow, excessive noise, or EC fans operating outside their efficient range. The review therefore included filters, dampers, leakage paths, duct transitions, operating schedules, and the difference between design demand and current demand.
Available project information showed that The available equipment data included a high-pressure centrifugal fan rated at 5.5 kW, approximately 8,000 m³/h and about 1,567 Pa, together with an air-handling unit rated at roughly 35,000 m³/h, 500 Pa external static pressure and an 18.5 kW motor. These values formed the initial basis for EC fan selection and field verification. These figures provided a traceable engineering reference, while final selection remained subject to measurement and verification.
The retrofit strategy combined efficient EC technology with airflow-path improvement. Before retrofit design, pressure losses across ducts, filters, coils, attenuators, and outlets were reviewed. The high-pressure fan and the air-handling unit were treated as separate duty points. Fan quantity, impeller size, installation space, and controls were then designed around measured airflow and pressure. This avoided the common mistake of installing a fan with an attractive free-air rating but insufficient pressure capability inside the real unit.
Control logic was equally important. EC fans can respond directly to speed commands, but efficiency gains depend on using that capability. Minimum ventilation, temperature or pressure feedback, scheduled setback, soft starting, and fail-safe operation were considered so that the fan would not simply run at maximum speed throughout the day.
This duty-specific method avoids oversizing and preserves speed-control flexibility for future process changes. As the source record did not provide a complete final savings figure, performance should be evaluated from post-retrofit power measurements and verified production conditions rather than an unsupported claim.
From a maintenance perspective, AISA PACIFIC SHENGRUI LIMITED considered the removal or reduction of belt-related service, easier access to fan modules, and clearer operating feedback. Trending speed and power can also help identify rising system resistance before it develops into a comfort or process complaint.
A credible retrofit closes the loop with commissioning. Airflow, pressure, power, sound, vibration, and zone conditions should be tested at representative loads. When those results are connected to operating hours and local electricity cost, the owner receives a realistic business case rather than a theoretical efficiency claim.
Frequently Asked Questions
Was a final energy-saving percentage verified for this workshop?
The source information did not include a complete final acceptance percentage. Performance should be confirmed from post-retrofit power and airflow measurements.
Where do EC fan energy savings come from?
Savings can come from efficient motors, direct drive, reduced mechanical losses, improved airflow paths, and speed control that follows actual demand.
Does an EC fan retrofit require changes to the control system?
Usually yes. The project should define speed commands, minimum ventilation, sensor feedback, alarm handling, and fail-safe operation with the existing controls or BMS.
How can maintenance requirements change after the retrofit?
Direct-drive EC fans can remove belt adjustment and replacement tasks, while speed and fault feedback can make developing airflow problems easier to identify.
How should long-term savings be verified?
Compare power and operating hours under equivalent loads, and normalize results for airflow, pressure, occupancy, production level, weather, and filter condition where relevant.
