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The COP of the latest fixed-speed centrifugal chiller is more than 6.4 and that of the latest variable-speed centrifugal chiller driven by an inverter reaches a 21.9 COP. This tremendous high performance is very effective for advanced heat source systems. Many energy conservation studies have been conducted on industrial heat source systems in Japan. But there have been few reports on the heat source systems for business use. This paper suggests an operation method for the latest fixed-speed and variable-speed chillers based on those unique high-performance characteristics. The effects of new planning and operation method suited for the heat source system for business use. High-performance data based on actual measurements are used to evaluate the energy conservation. In addition, this paper provides a new planning and operating method for a whole heat source system, including a new estimation method of cooling tower performance, which is a very important element. [ABSTRACT FROM AUTHOR]

This paper proposes a new index of the seasonal energy efficiency for chillers. The new index, the CSE (chiller seasonal efficiency) index, can be used by building designers for specifying the required chiller performance to manufacturers. This index has an advantage in that it is adaptable to multiple-chiller systems by setting six rating points to consider the difference in the COP due to the entering condenser water temperature as well as the part load. In addition, the use of the weighted harmonic mean equation improves the accuracy in predicting the seasonal COP In this paper, the rating condition for the CSE index is determined from the cooling load profile of office buildings in Japan. Using the CSE index, the advantage ofa variable-speed compressor chiller is presented. In the final part of the paper, the effect of the difference in chiller sequence control is discussed. [ABSTRACT FROM AUTHOR]

Hybrid ventilation systems have been previously shown to reduce cooling and ventilation energy consumption, however they often require large atria and do not sufficiently attenuate ambient noise, especially in urban areas. This paper presents a case study of a new ten story 83,700 ft² (7,780 m²) office building in downtown Tokyo with a hybrid ventilation system that uses only 1.7% of the building footprint for ventilation shafts. A special design approach is used to predict the hybrid ventilation potential of this building. As a first step, an airflow network model tool developed at MIT is used to predict the overall building conditions (temperature and airflow rate) inside the building when using pure and fan-assisted natural ventilation on a monthly basis. As a second step, Computational Fluid Dynamics (CFD) simulations are used to investigate airflow and temperature distributions in the open-plan office space and inform the design of exhaust airflow conditions. The building is currently under construction. Pure natural ventilation is predicted to provide comfortable conditions within the space, according to ASHRAE Standard 55, for 727 of a possible 1400 working hours between April and October in Tokyo. That time can be extended to 1018 hours if low-power fans that operate with less than 6% of the energy required for mechanical cooling are used to leverage the low airflow resistance of the building. CFD simulations indicate that the inlet angle of the incoming air into the room has a significant effect on the temperature distribution in the space. [ABSTRACT FROM AUTHOR]