L.T. Wong

Solar radiation model

Solar radiation models for predicting the average daily and hourly global radiation, beam radiation and diffuse radiation are reviewed in this paper. Seven models using the Angstrom-Prescott equation to predict the average daily global radiation with hours of sunshine are considered. The average daily global radiation for Hong Kong (22.3°N latitude, 114.3°E longitude) is predicted. Estimations of monthly average hourly global radiation are discussed. Two parametric models are reviewed and used to predict the hourly irradiance of Hong Kong. Comparisons among model predictions with measured data are made.

Field measurement of the air flow characteristics of big mechanically ventilated spaces

Abstract Air speeds induced by mechanical ventilation systems in the occupied zone are studied experimentally in seven railway stations in Hong Kong. Values of air speed at different positions are measured. From these values, air speed contours and turbulence intensities are calculated. Macroscopic numbers describing airflow in a space including the Reynolds number and the jet momentum number are estimated and their potential uses are discussed.

Preliminary studies on a new method for assessing ventilation in large spaces

Abstract Conventional methods of evaluating the ventilation system in large spaces using the age of air measured by tracer gas might not be practical. It is difficult to achieve ‘well-mixed’ condition throughout the huge space; and the cost of discharging large volume of tracer gas is too expensive. A new method for evaluating the ventilation in large enclosed spaces is proposed. This is based on the conventional step-down or decay method. Instead of filling up the entire hall with tracer gas, only a small control volume is considered. Tracer gas is discharged into this control volume with the ‘local’ mean age of air measured by studying the transient decay curve of the tracer gas concentration. Several positions are considered and the ‘ages’ measured can be used to evaluate the ventilation in the big hall. Field measurements were made in two big halls for illustrating the method. Further, the age measured in the control volume is compared with the age measured by thorough mixing of tracer gas in a smaller room.

Experimental studies on air diffusion of a linear diffuser and associated thermal comfort indices in an air-conditioned space

Abstract Indoor air flow induced by a linear diffuser in an air-conditioned environmental chamber was studied experimentally. Macroscopic numbers describing indoor air flow such as the Archimedes number, the Reynolds number and the jet number were measured. Evaluation of the thermal comfort using the air diffusion performance index (ADPI) and the percentage dissatisfied (PD) was made. Comparison between those indices and the macroscopic numbers for the air flow are discussed.

A proposed fire safety ranking system for old highrise buildings in the Hong Kong Special Administrative Region

A survey was carried out in a district in the Hong Kong Special Administrative Region (HKSAR) to investigate the fire safety aspects of old highrise non-residential buildings. Key parameters describing building characteristics and fire services provisions were identified. A 10-point ranking system concerning building characteristics and fire services provisions was proposed to quantify the fire safety level. The ranking system was designed with reference to the new requirements for fire safety in old highrise non-residential buildings in the HKSAR and would be a checklist to assess the fire safety provisions in the buildings. It was found that over 65% of the surveyed old highrise buildings did not have sufficient fire safety provisions. A distribution of the surveyed buildings with different fire safety levels was obtained. Immediate action must be taken to improve fire safety for those buildings that scored less than 6 points.

FIELD STUDY ON THE INDOOR THERMAL ENVIRONMENT AND CARBON MONOXIDE LEVELS IN A LARGE UNDERGROUND CAR PARK

Abstract Results of an indoor environment survey in a large underground car park in Hong Kong are reported in this paper. Field measurements were divided into three parts: (1) assessment of the thermal environment; (2) measurement of the carbon monoxide concentration; and (3) a survey on thermal comfort. The indoor air temperature, relative humidity, instantaneous airspeeds, turbulence intensity, and carbon monoxide concentration at different locations in the car park were measured. Design and operation of the installed ventilation systems were studied and the number of cars staying at the car park was investigated. Correlation relationships between the mean carbon monoxide and the mean air speed, the turbulence intensity, and the number of cars entering or leaving the car park were derived. Field studies of this kind are very important for providing ventilation system design data.

Thermal Environment Design of Atria in the Hong Kong Special Administrative Region: A Survey Study

A survey on 138 atria in the Hong Kong Special Administrative Region was carried out. The glass area and uses of the building, the geometry and location of the atria inside the building, and the design of the thermal environmental systems including the air terminal devices and the air distribution groups were studied. Based on the results, local atria are classified into different types. It was found that local atrium design is different from those in other countries. Aspects related to designing proper thermal environmental conditions were discussed.

Fire safety engineering: comparison of a new degree programme with the model curriculum

Abstract The curriculum design of a new degree programme in Building Services Engineering with Fire Engineering Specialism for the local fire engineering professionals in the Hong Kong Special Administrative Region is reported. The programme was approved by The Hong Kong Polytechnic University and offered in September 1997 with an intake of 25 students per year. The aims are to train fire engineers who can handle not only ‘traditional’ fire engineering systems, but also perform the ‘new’ procedure of fire safety engineering hooked up with the development of ‘performance-based fire codes’ in an ‘engineering approach’. Subject contents to be included in a fire safety engineering degree programme are proposed. A comparison of this new scheme with the model curriculum in Fire Safety Engineering is made. Coverage of topic areas on fire engineering and teaching hours are compared. Differences in the curricula have been identified and discussed.

A cost model for plumbing and drainage systems

The construction cost, yearly maintenance cost and yearly remedial cost of plumbing and drainage systems in buildings were investigated. Occupancy, age, piping material, pipe length and the size of the systems were surveyed in 63 buildings. Correlations for costs of the systems in commercial and residential buildings were made with the surveyed results. Length, material and size of the pipes provide good parameters to determine the system construction costs. Higher maintenance cost and remedial cost for aged systems were reported. Remedial cost for corrosion problems increased significantly for the aged systems.

PolyU/USTC Atrium: A Full-Scale Burning Facility -- Preliminary Experiments

The PolyU/USTC Atrium, a full-scale burning facility for atrium fire studies has been constructed at the University of Science and Technology of China (USTC). The atrium will be managed by USTC and the Hong Kong Polytechnic University (PolyU). The construction features of the facility are reported briefly, and further studies using this facility are outlined. Typical use of the facility is demonstrated by several smoke filling tests. The results on the smoke layer interface height were analyzed and compared with those predicted by zone models. It is observed that a zone model can give quite accurate prediction on smoke filling during most of the burning period. Language: en