modelling

This paper describes a methodology for simulating the transport of smoke and hot gases in buildings. The approach is based on the use of efficient CFD techniques and high performance computers to solve a form of the Navier-Stokes equations specialized to the smoke movement problem. The fire is prescribed in a manner consistent with a mixture fraction based approach to combustion, but the combustion phenomena themselves are not simulated. The mixing and transport of smoke and hot gases are calculated directly from an approximate form of the Navier-Stokes equations.

Displacement ventilation may provide better indoor air quality than mixing ventilation. Proper design of displacement ventilation requires information concerning the air temperature difference between the head and foot level of a sedentary person and the ventilation effectiveness at the breathing level. This paper presents models to predict the air temperature difference and the ventilation effectiveness, based on a database of 56 cases with displacement ventilation. The database was generated by using a validated CFD program and covers four different types of U.S.

The goal of this work was to assess the performance of two common ventilation systems, an exhaust and an exhaust supply system, in Swedish apartment buildings. Since correct air-exchange and interzonal airflows are important for removing contaminants and improving indoor air quality, these airflows were analyzed by systematic computer calculations when selected input parameters were varied around their default values.

Canada Mortgage and Housing Corporation (CMHC) conducted a series of attic research projects from 1988to1997. Initially, there were few field test data to substantiate how attics dealt with air and moisture transfer. The CMHC research developed a test protocol for attic airtightness and air change testing and then proceeded to field testing of a variety of attics in different climatic areas. An attic model, ATTIX, was referenced against test hut data and used to simulate attic performance across Canada.

This paper presents results of a project initiated by ASHRAE and the National Research Council of Canada. The project applies both physical and numerical modeling to atrium smoke exhaust systems to investigate the effectiveness of such systems and to develop guidelines for their design. In this paper, results were obtained from a series of tests conducted using a large-scale physical model.

The present Government has a target for reduction of the UK's carbon dioxide emissions of 20% of 1990 levels by the year 2010, which is in fact greater than the legal commitment set at the Kyoto summit on climate change in December 1997. Energy use in buildings accounts for approximately half of tl1e UK's annual carbon dioxide emissions and thus a reduction in the energy used in buildings is vital for this target to be achieved. A detailed knowledge of how energy is currently used is essential for assessing the potential for reducing the UK's C02 emissions.

A two dimensional model was developed to predict the infiltration load to a cold room through its doorway. The governing equations were derived and transformed into dimensionless form. The model showed that the infiltration load to a cold room depends on three dimensionless parameters: the Grashof number of the cold room, the aspect ratio of the room (height to width), and the opening ratio (height of doorway to height of the room). 1\ finite difference technique with a control volume approach was used to solve the governing equations.

The paper reports on progress to date on the development of a model for predicting energy use and the effect of conservation strategies in non-domestic buildings in the tropic and subtropics. This model considers lighting loads (L), both artificial and daylight, thermal loads (T) and ventilation effects (V). It is hoped, that when completed in late 1998, the model will provide a Lighting, Thermal, and Ventilation (LTV) advocacy tool for use in the early stages of the design processes of engineers and architects. This will provide vital feedback to the early design decisions.