The  use  of  split-type  air-conditioners  in  new apartment buildings becomes popular in Hong Kong. One requirement for their effective use is satisfactory heat rejection at the outdoor condensing units.  When a group of outdoor units is working together, the heat released by one condenser may affect the heat rejection rates at the others, and hence may deteriorate their performance.

This paper presents a mathematical model yielding a simplified representation of the thermal behaviors of ivy-covered walls. The model is integrated with a CFD program to implement simulation. Experimental results have been used to form the boundary conditions of numerical simulations. A series of parametric sensitivity analyses have been carried out for identifying the key factors that affect  ivy- coverings’ potential for reduction on cooling load of the buildings. These analyses indicate that ivy- coverings can considerably reduce the heat flux through the external walls that its cover.

When some faults take place in a thermal storage HVAC system, changing pattern of the temperature profiles of the thermal storage tank is useful to infer where some faults exist. Authors designed some parameters calculated from the temperature profiles of the thermal storage tank in HVAC system and their Fourier Transform to detect the difference between the normal and faulty state. Further, present paper shows practicality of two methods of parameter optimization, a differentiation rate increment method and  a  variable  selection  method,  with  an  actual application to a hospital.

In order to make proper radiative meshes with considering thermal distribution on solid surfaces, we inves- tigated the adaptive mesh generation method and per- formed parametric survey for a threshold which con- trols subdivision of mesh. With these studies we found that the adaptive mesh generation increase the accu- racy of predicting mesh surface temperature and air temperature even if the adaptive subdivision is rather soft one.

Air-conditioning systems with floor thermal storage can be used for cutting peak load and utilizing nighttime electric power. For the effective use of this system, however, thermal energy must be stored during the night in a way that does not waste energy. In this paper, an optimal heat input to such a system is investigated under prescribed external climatic conditions by making use of the optimal control theory.

Based on K- two equation turbulence model, we used PHOENICS 1.4 and numerically simulated air distribution and contamination field under different conditions in a vector- flow clean room. Special mesh system was introduced to deal with the quarter-circle- shaped inlets. Model experiments were also made. By analysis of numerical as well as experimental results, we made some predictions about flow characteristics, contaminant control effect and ventilation performance of this energy-saving clean room.

It is important to apply the natural light effectively for the low energy consuming daylighting design. A reliable standard sky is absolutely required that copies after the real sky luminance distribution for the simulation and evaluation of the daylit environment. Any applicable standard sky, however, has never found that shows accurately the actual state of daylight. A research work was carried out by the authors in order to establish a suitable sky model that can represent all the sky luminance distribution from the clear sky to the overcast sky continuously.

The research on provision of computational support for building performance analysis has traditionally concentrated on the building design phase. However, computational modeling can also effectively apply to the building operation phase. To explore this potential, we consider in this paper simulation- assisted control strategies to integrate contextual forces  (specifically  daylight)  into  building control systems.

In order to explain the effect of ventilation systems and airtight performance of houses in detached houses, the investigation was made on a simulation program which calculates the ventilation rates and indoor air quality. The ventilation rates and the concentrations of CO2 , CO and formaldehyde in general Japanese houses with three kinds of ventilation systems were calculated through a year in three cities of Japan. The results of the simulation showed a case in which the concentrations of the pollutants are not acceptable.

This paper introduces a method to simulate the day-light performance of buildings using geostational me- teorological satellite images. A new statistical method enables to estimate global and direct solar irradiance values at hourly intervals by the pixel values of satel- lites images. Luminous efficiency functions convert the global and direct irradiance values into diffuse and direct daylight illuminance values. The daylight source model is combined with a daylight calculation program to calculate spatial and temporal distributions of illu- minance and luminance.