ST-16-C068 -- Evaluation of Variable Refrigerant Flow Systems with Comparisons to Traditional HVAC Systems: System Design Comparisons ✓ Most Recent

This paper describes the design and evaluation of the HVAC systems recently installed in Umyoen R&D campus in Umyoen, South Korea. The campus consists of six similar buildings, A, B, C, D, E, and F. Four of these buildings, A, B, D, and E are equipped with a mix of traditional HVAC systems consisting of centrifugal chillers and absorption chillers, and variable refrigerant flow (VRF) systems to meet their cooling and heating needs, while building C is 100% served by VRF systems and the standard floors of building F are 100% covered by traditional HVAC systems. Thanks to the similarities in architecture, construction, occupancy, and thermal load of these six buildings, this project provides a unique opportunity to compare VRF system, traditional HVAC system, and their combination over a wide range of aspects: energy, comfort, maintenance costs, and initial investments. In this paper, we will focus on the system design aspects and share the design experiences of how to use different HVAC systems to serve the heating and cooling needs of a large scale R&D campus to meet the goals of building energy performance, indoor quality, human comfort, and building life cycle costs. Various HVAC systems, including VRF systems, traditional HVAC systems, and their combination are analyzed and compared. Detailed system life cycle (LCC) analysis demonstrates that VRFs can provide an energy efficient and cost effective heating and cooling solution for large commercial buildings. Various technical improvements implemented in this project will be described in detail, such as discharge temperature control strategy, partial EEV shut off for idle indoor units, and DX coil designs in AHUs served with VRF units.