Improving variable refrigerant flow system operation and energy efficiency: A study of the urban Minoh campus, Osaka, Japan

Suzuki, Toshihiro; Shimoda, Yoshiyuki; Matsuura, Shuta et al.

Applied Thermal Engineering, 2026, 289, 129738

Number of Access:19（2026-04-05 14:33 Counts）

Identifier to cite or link to this item: https://hdl.handle.net/11094/104030

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Title
Improving variable refrigerant flow system operation and energy efficiency: A study of the urban Minoh campus, Osaka, Japan
Creator
NRID
1000000522070 1000000522070
ORCID
0009-0003-3443-4173 0009-0003-3443-4173
researchmap permalink
toshihiro.suzuki toshihiro.suzuki
Scopus Author ID
55731719800 55731719800
CreatorName
Suzuki, Toshihiro
NRID
1000020226278 1000020226278
ORCID
0000-0002-4487-0089 0000-0002-4487-0089
researchmap permalink
read0014119 read0014119
Scopus Author ID
15081121700 15081121700
CreatorName
Shimoda, Yoshiyuki
CreatorName
Matsuura, Shuta
CreatorName
Shiochi, Sumio
Subject
Energy efficiency
Energy management
Medium-sized building
Variable refrigerant flow
Description
Suzuki T., Shimoda Y., Matsuura S., et al. Improving variable refrigerant flow system operation and energy efficiency: A study of the urban Minoh campus, Osaka, Japan. Applied Thermal Engineering 289, 129738 (2026); https://doi.org/10.1016/j.applthermaleng.2026.129738.
Abstract
Variable refrigerant flow (VRF) systems are widely adopted in commercial and institutional buildings; however, their actual performance often diverges from design expectations due to oversizing, low-load operation, and user-driven control behaviors. To clarify these issues and quantify their impact, this study conducts a comprehensive operational analysis of 100 outdoor units and 650 indoor units installed across a large multi-purpose academic building at Osaka University's Minoh Campus. One-year high-resolution operational data were examined to characterize part load ratios (PLRs), COP behavior, refrigerant-cycle conditions, and inefficiencies caused by excessive temperature settings, nighttime unattended operation, and uneven indoor-unit usage patterns. The analysis identified frequent low-load operation and oversized outdoor units as primary causes of performance degradation. After implementing operational energy-saving measures—including optimal temperature settings, reduced nighttime operation, and improved control awareness—the annual VRF energy use decreased by 12.9%. Additionally, a capacity optimization simulation revealed that resizing oversized outdoor units could yield a further 15.9% reduction, emphasizing the need to address both operational and design-level inefficiencies. The study demonstrates that substantial energy savings can be achieved through combined operational improvements and capacity optimization, even in large-scale, diverse-use campus buildings. These findings offer practical insights for enhancing VRF system performance and provide evidence-based guidance for improving energy management in buildings employing distributed air-conditioning systems.
Publisher
Elsevier Ltd
Source Title
Applied Thermal Engineering
Volume (Issue)
289
Page
129738
Date of Issued
2026-03-01
Language
English
Handle URL
https://hdl.handle.net/11094/104030
PISSN
13594311
Relation.isIdenticalTo
DOI (Publisher Version)
https://doi.org/10.1016/j.applthermaleng.2026.129738
Access Rights
open access
CopyRight
This article is licensed under a Creative Commons Attribution 4.0 International License.
oaire:version
Version of Record
Category
学術雑誌論文 Journal Article