Detailed Comparison of the Operational Characteristics of Energy-Conserving HVAC Systems during the Cooling Season

Abstract

To provide useful information concerning energy-conserving heating, ventilation, and air-conditioning (HVAC) systems, this study used EnergyPlus to analyze in detail their operational characteristics and energy performance. This study also aimed to understand the features of the systems under consideration by investigating the dry-bulb temperature, relative humidity, and airflow rate at major nodes in each system’s schematic. Furthermore, we analyzed the indoor environment created by each HVAC system, as well as examining the cooling energy consumptions and CO2 emissions. The HVAC systems selected for this study are the variable air volume (VAV) commonly used in office buildings (base-case model), constant air volume (CAV), under-floor air distribution (UFAD), and active chilled beam (ACB) with dedicated outdoor air system (DOAS). For the same indoor set-point temperature, the CAV’s supply airflow was the highest, and VAV and UFAD were operated by varying the airflow rate according to the change of the space thermal load. ACB with DOAS was analyzed as being able to perform air conditioning only with the supply airflow constantly fixed at a minimum outdoor air volume. The primary cooling energy was increased by about 23.3% by applying CAV, compared to VAV. When using the UFAD and ACB with DOAS, cooling energy was reduced by 11.3% and 23.1% compared with VAV, respectively.

Optimization-informed rule extraction for HVAC system: A case study of dedicated outdoor air system control in a mixed-humid climate zone

“…(2) Energy efficiency . As DOAS decouples the functions of covering total sensible load, latent load, and ventilation requirement using the same HVAC system, the DOAS often requires less volumetric airflow rate compared to the other traditional HVAC systems (i.e., CAV or VAV systems) [15] . These traits of the DOAS not only allow to downsize the HVAC equipment (e.g., fan, chillers, boilers) but also reduce the energy consumption in HVAC operation [9] , [11] .…”

HVAC Energy Saving Strategies for Public Buildings Based on Heat Pumps and Demand Controlled Ventilation

“…VAV systems' improvements highly depend on the system controls that are implemented, an analysis of which is presented in [31]. For example, in [32] the introduction of VSD has provided a cooling energy saving of almost 23% compared to constant speed HVAC systems.…”

Introduction to the Dynamics of Heat Transfer in Buildings

“…Examples of building energy management analyzes using increased thermal capacitance and thermal storage management are shown in work [27]. Tools for increasing energy efficiency in the examples [28] and in the integration of HVAC systems are presented in the works [29,30].…”