A zonal model has been nested within a multizone model to allow increased resolution in the prediction of local air flow velocities, temperature and concentration distributions between and within rooms. Simulations from the new program have been compared with measurements and results from other models.
The current design standard BS EN ISO 7730 is based upon the work of Fanger dated 1995, dealing with a steady-state human heat balance model that leads to a prediction of the sensation of human thermal comfort for a given set of thermal conditions. That model was then developed for "conventional" environments. But is the current standard still applicable to more sophisticated environments such as offices with chilled ceiling, in combination with displacement ventilation ? This paper presents findings from a study that sought to answer that question.
This paper presents a simplified system based on a new air supply opening model along with a numerical method to accelerate and simplify the convergence procedure of predicting air distribution in ventilated rooms. The new numerical method is called error pre-treatment method. It is simpler than multi-grid method and effective for SIMPLE algorithm commonly used for indoor airflow simulation.
The authors have developed a whole-field measuring technique that allows the visualization of air temperatures and airflow patterns over a large cross-section. For that measurement, an infrared camera and a measuring screen placed in the airflow are used. Thanks to that technique, real-time images within large areas can be recorded and transient events can be captured. The method was applied to a flow from a low-velocity diffuser in displacement ventilation.
Five air terminal devices (ATD) have been tested in a typical office workplace with a breathing thermal manikin. Tracer gas used to identify the amount of air inhaled and the amount of exhaled air re-inhaled. An index was used to assess the performance of ATD.
The author gives practical advices in the design of local exhaust ventilation system (mainly hoods) to capture the contaminant and general ventilation systems to dilute the offending chemical contaminant to acceptable effects. The effect on local environment is studied too.
Air tighness of ventilation network is very important, so the manufacturers have developped sets of new sealed fittings. These new equipments have been tested in CETIAT laboratory. Results show good performance in term of air tighness and installation time.
The new French regulation about energy performance of buildings (RT 2000) specifies airtighness criterion for ventilation network. The author gives a methodology to measure the overall airtighness of ventilation installations on site. Examples based on a school and an apartment building are given.
The objective of this European Directive, which has to be transposed in national laws in European countries before 4 January 2006, is to promote the improvement of the energy performance of buildings, taking into account outdoor climatic conditions and local conditions, as well as indoor climate requirements and cost-effectiveness.
The directive lays down esuirements as regard :
a - the general framework for a methodology of calculation of the integrated energy performance of buildings (including aspects such as ventilation and indoor climatic conditions);
Seven air supply and return diffusion layouts were tested to determine their effects on air distribution, air change efficiency and ventilation efficiency for workstations in an open-plan office. This document describes and comments the results of these measurements.
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