Annual Energy Consumption Cut-Off with Cooling System Design Parameter Changes in Large Office Buildings

Abstract

A variety of greenhouse gas reduction scenarios have been proposed around the world to ensure sustainable developments and strengthen the global response to the climate change. To cope with this, it is urgently needed to reduce the amount of energy used for the heating, ventilating, air conditioning, and refrigerating (HVAC&R) systems in large buildings. This study discusses the reduction of cooling energy in large office buildings through the minimization of changes in components and equipment, such as heat source equipment and pumps, changes in the layout and operating methods of chilled water circulation pumps, and changes in the temperatures of chilled and condenser water. To do this, this study targeted an entire cooling system consisting of a hydronic system, a chiller, and a cooling tower, and conducted a quantitative analysis of the energy consumption and of the reduction achieved through a change in the pumping system type in the cooling system and a change in the Korean standard design and temperature of chiller and cooling tower via EnergyPlus simulations. The simulation results showed a cooling energy reduction of 103.2 MWh/yr, around 15.7%, where the primary constant-speed system (Case A) was changed to a primary variable-speed pump (Case B) in the configuration with a chilled water circulation pump. To reduce the cooling energy further, annually 142.3 MWh, around 21.7%, Case C in this study changed the outlet temperature of the chiller and temperature difference from 7 °C, 5 K to 9 °C, 9 K. Finally, when applying a change in the condenser water production temperature from 32 to 23.9 °C in accordance with ASHRAE Standard 90.1 for Case D, a cooling energy saving of 182.4 MWh/yr was observed, which is about 27.8%.

Environmental Footprint and Economics of a Full-Scale 3D-Printed House

“…The ISO standard (EN ISO 6946:2008) reported the key factor to indicate the thermal properties of the building is heat transfer (U) in which lower U-value indicates higher energy savings [30]. The U-value [31] and the energy transfer or heat flow (Q) [32] were calculated using Equations ( 1) and (2) [33,34]:…”

“…The design temperature outside and inside the house was specified by local guidelines as 46 • C and 24 • C, respectively. Moreover, the U-value of the floor and roof slabs were obtained from local standards and they were compared to ASHRAE (American society of heating, refrigerating and air-conditioning engineers) specifications based on perimeter to area ratio and thermal resistance values [33,34].…”

A Study on the Energy Reduction Measures of Data Centers through Chilled Water Temperature Control and Water-Side Economizer

“…Because chillers account for 50% of the energy consumed by cooling systems [3], various studies have been conducted to reduce the energy of a chiller in heating, ventilation, and air conditioning (HVAC) systems. Ha et al (2020) analyzed the energy consumption according to temperature variation and chilled water outlet temperature of the main cooling period in order to increase the coefficient of performance (COP) of a chiller [4]. The results showed that energy savings of up to 12.4% were realized at a chiller water exit temperature of 7 • C and a temperature difference of 10 K. Thu et al (2017) analyzed the changes in the chiller COP and cooling capacity according to the increase in the temperature of chilled water for mechanical vapor compression (MVC) chillers [5].…”