Search Results (3)

In the heating supply systems in apartment buildings utilizing district heating, the supply water temperature setting is a critical control for providing sufficient heating and effective usage of the heating energy. Conventional water temperature control methods such as fixed temperature (FT) control can result in energy wastage and outdoor air temperature reset (OTR) control cannot reflect the variation in the heating demands of households because it only considers the outdoor air temperature. Therefore, this study proposes an advanced control method called flow-based residential energy demand (f-RED) control, which sets the supply water temperature based on the outdoor air temperature and household heating demands (i.e., the changes in the circulated heating water flow). To determine the performance of the proposed method compared to the conventional one, this study utilizes building energy simulation. The simulation analysis results confirm that the f-RED control method appropriately sets the supply water temperature based on a combination of the two factors, supplies heat according to heating demands, and reduces the energy consumption of the circulation pump by approximately 1.6% and that of the secondary pump by 4.2%. Thus, the f-RED control method is able to utilize heat energy more effectively and efficiently than the conventional control method. Full article

As building systems account for almost half of the total energy consumed by the building sector to provide space heating, cooling, and ventilation, efficiently designing these systems can be the key to energy conservation in buildings. Dual VAV systems with an effective control strategy can substantially reduce the energy consumption in buildings, providing a significant scope of further research on this system configuration. This paper proposes to utilize the warm air duct of the dual VAV system as a dedicated outdoor air (DOA) unit when no heating is required, which allows the cooling load to be effectively distributed between two ducts. A specific control sequence is proposed with different supply air temperature reset strategies to estimate the heating, cooling loads, and fan power energy consumption of the proposed system. A simple two-zone office building is taken as a preliminary case study to simulate the airflow rates and fan power of a single duct VAV and proposed dual VAV systems to illustrate the concept. Finally, a larger multi-zone office building is simulated to measure the annual heating, cooling loads, and fan power energy and compare the energy savings among the systems. The results show significant fan power reduction ranging from 1.7 to 9% and notable heating energy reduction up to 76.5% with a small amount of cooling load reduction varying from 0.76 to 2.56% depending on the different locations for the proposed dual VAV systems. Further energy savings from different supply air temperature reset strategies demonstrate the opportunity of employing them according to climates and case studies. The proposed dual VAV system proves to have the potential to be adapted in buildings for the purpose of sustainability and energy savings. Full article

The number of domestic apartment houses in South Korea that use district heating is steadily increasing. In addition, most Korean residential buildings use radiant floor heating systems. For such systems, the heating water temperature supplied by a heat exchanger in a mechanical room serves as one of the critical control parameters for providing heat to individual residential apartments. Fixed temperature (FT) and outdoor temperature reset control (OTR) have conventionally been used to adjust the heating supply water temperature. However, both control methods have a major technical weakness; they do not reflect changes in residents’ heating use. To overcome this issue, this study proposes a new method for controlling the heating supply water temperature, called Residential Energy Demand (RED). To verify the proposed method, researchers conducted both simulation- and experiment-based tests. The RED control method achieved about 4% reduction in heating energy consumption compared to the conventional OTR control process. In addition, the RED control method increased the average indoor temperature by 0.17 °C during the heating period. Therefore, this study demonstrates that the proposed control method is capable of achieving energy savings and a warmer thermal indoor environment. Full article