modelling

Railway platform spot cooling has become an increasingly attractive means to improve thermal comfort conditions of existing subway stations. This paper presents a systematic approach to evaluate the effectiveness of platform spot cooling. The subway environment is first analysed by a simple onedimensional network model, which is able to estimate the bulk air temperature from the available spot cooling. The localized effects of spot cooling are then investigated using CFD.

The 3DFLOW code has been developed based on:
· The standard three-dimensional K-epsilon two-equation turbulence model;
· A modification for buoyancy effects;
· Wall functions applied to deal with solid boundary conditions;
· An adaptation of the SIMPLE algorithm.
The representative indoor air flows in conditioned spaces, including downward mixing, partition and displacement ventilation cases, were simulated and analysed in detail using the 3DFLOW code. Good agreement was found between the numerical predictions and experimental data.

The behaviour of particles in air flow is important for identifying those in various locations in ventilated space. The main reason for this study is to propose a new modelling concept to determine a realistic distribution of particles of different sizes in a space. The goal for this investigation is to divide particles into groups according to their behaviour in air and to improve the existing settling model. The growth of particle aerodynamic diameter in higher relative humidity is also presented.

Data exchange is the process by which information is transferred between the engineer and software and between one piece of software and another. Building and plant simulation involves handling large data sets describing constructional details, system components and reference data. The time required to prepare and check the data is significant and is one obstruction to the widespread use of simulation within the design process. Links between drafting systems and analytical tools offer an obvious way to speed up the process and reduce input errors.

The application of a radon model is useful to understand the processes that drive the radon gasbehaviour from its sources to its accumulation indoors. Since in a given inhabited house the detailedknowledge of the values of all the parameters that affect indoor radon levels is not available, theresponse of the model has to be explored in a reference site in which all the parameters are supposedto be known. We call this site the reference configuration.

Radon goes through four stages from its formation until it reaches a living environment: i) itsgeneration in the source medium, ii) its migration in the source medium, iii) its entry into a dwelling,and iv) its accumulation indoors. Many parameters of different origin take part at each stage, and mostof them are time-dependent. In this paper we discuss the requirements that an ideal model, whichconstitutes a Global Dynamic Radon Model (GDRM), should fulfil to predict indoor radon levels inliving areas of inhabited houses.

Numerical modelling is a powerful tool for studies of soil gas and radon-222 entry into houses. It isthe purpose of this paper to review some main techniques and results. In the past, modelling hasfocused on Darcy flow of soil gas (driven by indoor-outdoor pressure differences) and combineddiffusive and advective transport of radon. Models of different complexity have been used. Thesimpler ones are finite-difference models with one or two spatial dimensions. The more complexmodels allow for full 3D and time dependency.

The application of system identification techniques to the energy performance assessment of buildings and building components requires a high level of knowledgeof physical and mathematical processes. This factor,combined with the quality of the data, the descriptionof the monitoring procedure and test environment, together with the experience of the user of the analysis software itself, can produce varying results from differentusers when applying different models and software packages.

The CLIM 2000 software environment [1] was developed by the Electricity Applications in Buildings Branch of the French utility company, Electricité de France. This software which has been in operation since June 1989, allows the behavior of a whole buildi

In 1993, the R & D Division launched the IntelChaud project with a view to improving the comfort provided by individual gas-fired boilers used for domestic hot water production. This study was conducted in partnership with two French boiler manufacturers and was therefore applied to two particular cases. The work performed for this study has led to substantial improvements in boiler control through the use of sophisticated numerical control systems.