IAQ Modelling

Modelling of the Air Quality and Ventilation in Indoor Environment

Dept. of Building
National University of Singapore
1998 – 2001

This page is copied from the original website.

SIGNIFICANCE OF THE RESEARCH

The research has resulted in the development of a design guide and a series of multi-factorial models. The design guide, for rooms in buildings, will assist Air-conditioning and Mechanical Ventilation (ACMV) designers and interior designers in the formulation of designs for the air distribution system in central air-conditioning systems and the interior layout of furniture, respectively.

A series of multi-factorial models have been developed to characterise the indoor contamination and thermal comfort dimensions.

The design guide and multi-factorial models assist the ACMV designers and interior designers to provide, in their designs, better air quality and comfort for occupants in the indoor environment.

INTRODUCTION

The pattern of airflow within a building or within individual rooms can have a considerable impact on the energy performance of ventilation systems. In addition, the behaviour of airflow influences the propagation of airborne pollutants, the thermal environment and general comfort conditions. In order to optimise design and ensure a healthy interior, increasing attention is being focused on building airflow behaviour and mixing characteristics.

In many instances, it is difficult to consider in detail the pattern of airflow and its influence on the thermal condition and pollutant transportation pattern. Factors such as the interaction of leakage openings, the location of supply and extract terminals, room layout, occupant patterns and the location and strength of heat sources all combine to influence the pattern of the flow. This is of paramount importance for the comfort and health of occupants in the workspace at the offices of a commercial building which is generally limited. This situation is further aggravated by the high rental cost, especially in countries like Singapore, which has limited land resource. There is minimal consideration for the effect of the layout of the diffuser and furniture (e.g., with low partitions) on the airflow and pollutant dispersion patterns in the indoor environment to achieve better air quality and comfort conditions. The objective of this research project was to develop a design guide and multi-factorial models to assist ACMV designers and interior designers to achieve a comfortable and healthy indoor environment.

METHODOLOGY

This research project has taken both the empirical measurement and Computational Fluid Dynamics (CFD) modelling approaches. Measurements of indoor air parameters, such as air velocity, temperature and concentration of pollutants are conducted in the laboratory (i.e., the environmental chamber) and in the field (i.e., the lecture room and office). Likewise, CFD modelling is used to simulate the distribution pattern of the indoor air parameters in the same premises. The validity of the predicted airflow, temperature and pollutant dispersion results is evaluated by comparing them against the measured results. These validated models will provide a valuable insight into processes which are difficult to study experimentally for prospective problems.

Figure 1. Airflow study in a lecture theatre.

MAJOR FINDINGS

The three major findings from this research project are:

1. A simplified square-ceiling diffuser model has been developed successfully to simulate airflow, temperature and pollutant dispersion patterns in indoor environment.
2. A qualitative design guide for optimum locations of the supply diffuser and layout of furniture in small and large rooms has been developed.
3. A series of charts based on the effects of the layout of the diffuser and furniture on the airflow and pollutant dispersion patterns have been derived from the multi-factorial models. These charts guide the ACMV designers and interior designers in the formulation of the design for the layout of the diffuser and furniture respectively, to achieve a comfortable and healthy indoor environment.

FUTURE WORKS

There are plans to develop a diffuser model for other types of diffusers, such as linear and circular diffusers, and to establish multi-factorial models for other parametric variations, such as size of the room, types of diffusers, and combinations of linear and square diffusers serving the peripherals and central zones in an office space. A comprehensive handbook can be prepared for the ACMV designers and interior designers.

CONTACT DETAILS

Principal Investigator: Assoc. Prof. David Cheong
Research Assistant: Ery Djunaedy