Cooling load

Cities all over the world have been warming up in the summer over the years. Seoul, Korea, is also an example of how a city was transformed into an urban heat island. Green areas produce social, economical and environmental benefits in highly populated urban areas. This study is to investigate the micro-climate changes and urban-scale cooling load reduction by the recently restored Cheonggye stream, also known as Cheonggyecheon, in Seoul, Korea.

Guiyang is the capital city of Guizhou province in southwest China, located in the Mild Climatic zone in China. With the economy booming in recent years, the energy consumption in heating and cooling buildings in Guiyang continues to increase. This paper presents a computer simulation study using DeST software package, which is broadly used to simulate building energy consumption in China.

Energy recovery ventilator (ERV) is generally installed in an air-conditioning system to recycle the cooling load of exhaust air. However, air conditioning systems with the single ERV can not meet with outdoor air load and indoor cooling load in summer, which will cause fluctuation of indoor temperature. The goal of this study is to analyze such a fuctuating scenario of the indoor temperature. CFD and subjective evaluation are used in this study.

In Japan, wooden detached residential houses are common; the wood components within a wall may undergo decay because of condensation in the wall or flushing defects, which can be a concern. The temperature distribution throughout the house, such as a high temperature in the attic space, can cause discomfort to the occupants. A double-skin system of room-side air gaps is considered to be an effective technique to handle these problems.

In this study, the TRNSYS simulation engine was used to investigate the shading and cooling effect of roof added photovoltaics. The local weather conditions were introduced in the data reader component. The sol air effective temperatures were modeled in the roof –air boundary layer, while a single zone model was used for the heat transfer calculation, both in bared and PV shaded  roof. The simulation was validated by experimental data of a PV installation at the roof of the Department of Environmental & Natural Resources Management.

Detached residential wooden houses are a common type of housing in Japan. Decay of wooden components within the walls caused by condensation or defective flushing, is sometimes an issue. To solve this problem, a double-skin system with a room-side air gap was developed. In this system, during summer, the airflow that is driven by ventilation fans moves through the room-side air gap in the wall, and removes heat load either from the inner surface of the insulation material, or from the surface adjacent to the rooms inside.

The effects of roof window on ventilation flow rates and reduction of cooling loads in densely populated areas were investigated by using building simulations. In May of the intermediate season, when utilizing roof window, the cumulative number of air exchanges increased by 9 % to 12 % compared to that when the windows at side walls remained open only during the daytime. When the building coverage ratio increased from 0 % to 20 %, the cumulative number of air exchanges decreased and the cumulative cooling loads increased.

A simulation study on the reduction of cooling loads by utilizing cross-ventilation was performed for a typically shaped house as defined by the Architectural Institute of Japan. A reduction in cooling load of around 50% could be achieved when the windows were opened liberally at night compared with the cooling load when all the windows remained closed, regardless of building coverage ratio.

This paper aims at pointing out that how a District Cooling system can be a more energy efficientsolution compared with a decentralized cooling solution. In order to give a fair comparison, the authorapplies equivalent electric power coefficient of performance. This comparison approach will beinstructive for designing an energy efficient cooling solution in China.Firstly, the paper gives the definition, components and possible energy source of a District CoolingSystem.