Open Access

ARTICLE

Impact of Duty Cycling HVAC Systems on Thermal Comfort, Energy Consumption, and Operational Costs

Alya Penta Agharid¹, Indra Permana², Linlan Chang¹, Yi-Han Luo², Fujen Wang^2,*

1 Graduate Institute of Precision Manufacturing, National Chin-Yi University of Technology, Taichung, 41170, Taiwan
2 Department of Refrigeration, Air Conditioning and Energy Engineering, National Chin-Yi University of Technology, Taichung, 41170, Taiwan

* Corresponding Author: Fujen Wang. Email:

(This article belongs to the Special Issue: Innovative Strategies for Energy-Efficient Buildings in a Sustainable Future)

Energy Engineering 2025, 122(9), 3839-3866. https://doi.org/10.32604/ee.2025.068586

Received 01 June 2025; Accepted 29 July 2025; Issue published 26 August 2025

Abstract

Air conditioning (AC) is essential for maintaining indoor comfort during Taiwan’s hot and humid summers but significantly contributes to increased energy consumption. This study evaluates the effects of AC duty-cycling strategies on energy performance, thermal comfort, and operational costs in office environments. Duty-cycling was implemented using a building energy management system (BEMS), which remotely controlled the ON/OFF cycles of AC units. Five duty-cycling modes were tested, with some modes incorporating air circulation during OFF periods. Field measurements of energy consumption, temperature, humidity, and air velocity were conducted and integrated with thermal comfort analysis tools to calculate predicted mean vote (PMV) and percentage of dissatisfied (PPD) values. The objective was to achieve energy savings while maintaining acceptable thermal comfort levels. Results show that Mode A achieved the highest energy savings, reducing monthly consumption by 40.79%; however, it slightly exceeded the PMV threshold (+0.5) and recorded a PPD greater than 10%, indicating reduced occupant comfort. In contrast, Mode C provided a better balance, achieving a 27.61% reduction in energy consumption while maintaining a PMV of +0.28 and a PPD of 7.49%, both within acceptable comfort limits. Despite the energy-saving benefits, not all duty-cycling modes ensured satisfactory thermal comfort. Additionally, the cost analysis revealed that Mode A achieved the lowest monthly electricity cost (NTD 8476.18/USD 263.38), while Mode C incurred a higher cost (NTD 10,363.00/USD 322.01), highlighting the trade-off between energy savings, comfort, and economic impact.

---

Keywords

---