A Study on the Changes in the Heat Source Capacity and Air-Conditioning Load due to Retrofit; Focusing on a Large Office Building in Korea

Abstract

In an office building, the internal heat and the skin load are both expected to change. Thus, this study is an initial step that searches for optimum replacement measures when a heat source system is replaced on an office building in Korea. The operation status of office buildings in Korea was investigated, and the heat source capacities at the retrofit and the design times were quantitatively studied to determine the optimum capacity during of a heat source during retrofit. For the four retrofit scenarios, the maximum cooling and heating loads were calculated to show that, when retrofit is performed, the maximum cooling and heating loads are decreased by 40%, while the heat source capacity is reduced by around 43%. This is believed to be because of the replacement of the window chassis, which are better sealed with higher heat insulation performance, due to the enhanced design criteria for exterior load designing, and an improved installation process. Concerning the air-conditioning load, the influence of the internal heat load turned out to be significant, indicating that such a factor should be considered when retrofit. Thus, if the heat source capacity at the initial design time is applied equivalently during the office building retrofit, it would lead to degradation in energy efficiency due to the excessive design. Thus, it is necessary to calculate a heat source capacity by reflecting the operational and current status of the load in an actual building at the time of a retrofit.

Consumption Optimization in an Office Building Considering Flexible Loads and User Comfort

“…Recently, a main concern in energy consumption minimization topics is user comfort [8] and keeping a balance between energy consumption minimization and user preference needs that are formulated with adequate constraints in order to observe optimization purposes and user easement at the same time [10]. Mostly, in office buildings, more attention is paid to air conditioners (ACs) [11,12], while according to [13], 29% of the total energy consumption in office buildings occurs due to lighting. The lights in offices are considered as flexible loads if these are controllable by existing equipment [14].…”

“…Focusing on the user comfort, the power reduction in consecutive periods for a certain device can be annoying for the user because the user could feel light reduction or thermal inconvenience for a prolonged period. Therefore, Equations (11) and (12) are assigned to prevent power reduction os certain lights and ACs, respectively, in consecutive periods.…”

“…It also considers constraints (8), and (9) for applying restrictions in specific periods and (10) is defined to limit the power reduction of the lights in specific places based on user preferences. In the last stage, constraints (11), and (12) are dedicated for preventing power reduction in consecutive periods in certain devices.…”

“…Comfort 1 (C1) focuses on variations of constraints (6) and (7) while constraints (8) to (12) are equal to base values in scenario A. Comfort 2 surveys the variations of constraints (8), (9), and (10) while constraints (6), (7), (11), and (12) maintain their base values in scenario A. Comfort 3 (C3) considers the variation of constraints (11) and (12) whereas constraints (6) to (10) are in the base state of scenario A.…”

“…Comfort 2 surveys the variations of constraints (8), (9), and (10) while constraints (6), (7), (11), and (12) maintain their base values in scenario A. Comfort 3 (C3) considers the variation of constraints (11) and (12) whereas constraints (6) to (10) are in the base state of scenario A. In each class of C1, C2, or C3, the related parameters are multiplied by values which are presented on the x-axis of Figure 17.…”