Abstract
The non-insulated underfloor supply plenum and the heat gain of the cool supply air into supply plenum results in significant magnitude of thermal decay defined as the supply air temperature rise. Eventually, these changes have influence on the room air stratification, causing negative effects throughout whole system. Therefore, for the optimization of UFAD system, it is important to understand these fundamentals and relevant effects on the overall system operation. In this study, comparative analysis was conducted during cooling period using validated EnergyPlus model, after employing different operational configurations related to room air stratification and thermal decay. The thermal behavior and cooling energy performance were analyzed by observing the convective heat transfer, thermal decay, airflow, stratification among different operational configurations. As a result, it was observed that the existence of non-insulated supply plenum have influences on the thermal behavior in occupied zone, and the corresponding heat transfer has load reduction effect of the space by about 40%. However, there were still significant amounts of cooling energy consumption in the form of thermal decay despite the reduced cooling load, indicating that unintended and additional energy consumption was occurred in supply plenum. In addition, return air temperature rise by the room air stratification increased the cooling coil load. Eventually, these effects canceled each other out. As a result, compared to CBAD system, standard UFAD system consumed more electric energy by approximately 30%, and for fully-insulated UFAD system, 6% energy saving could be achieved.
Original language | English |
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Pages (from-to) | 262-274 |
Number of pages | 13 |
Journal | Energy and Buildings |
Volume | 176 |
DOIs | |
Publication status | Published - 2018 Oct 1 |
Externally published | Yes |
Bibliographical note
Funding Information:This work was supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Trade, Industry and Energy (No. 20184030201900 ).
Publisher Copyright:
© 2018 Elsevier B.V.
Keywords
- Energy modeling
- EnergyPlus
- Room air stratification
- Thermal decay
- Underfloor air distribution
- Underfloor supply plenum
ASJC Scopus subject areas
- Civil and Structural Engineering
- Building and Construction
- Mechanical Engineering
- Electrical and Electronic Engineering