The purpose of ventilation is to dilute indoor contaminants that an occupant is exposed to. In a multi-zone environment such as a house, there will be different dilution rates and different source strengths in every zone. Most US homes have central HVAC systems, which tend to mix conditions between zones. Different types of ventilation systems will provide different amounts of dilution depending on the effectiveness of their air distribution systems and the location of sources and occupants.

The amount of energy used to heat and cool buildings is a significant concern that impacts on issues from national policies to personal desires of cost and comfort. The key to achieving optimum performance is the control of the energy flows in the building and its environment. Such control is secured through monitoring and altering the driving sources to maintain the desired thermal and air quality conditions in a space while external and internal conditions (e.g. seasonal climate, indoor heat gains, pollutants etc.) change over time.

This paper addresses the process of optimising the benefits of the natural (air) environment in the case of a high density city in which the amount of building volume is ultimately constrained. It is hypothesised that, in densely built cities, the amount of vertically placed gaps, permeability and porosity of the cityscape will affect the ventilation and wind environment. Wind tunnel experiments are described in which different amounts and positions of gaps were applied to a simplified city layout.

The potential for prediction error when using computational fluid dynamics (CFD) for investigating internal building airflows is assessed in the current paper. The ability of a proprietary CFD code, CFX, to simulate buoyant and forced airflow regimes, typical of a naturally ventilated building, are investigated using two experimental case studies from the literature. Comparisons are then made between simulated and measured airflows for a naturally ventilated building.

An energy and cost analysis has been performed which compared a dedicated outdoor air system (DOAS) with chilled radiant cooling panel (CRCP), designed for an official building located in the hot and humid climate of Chennai, India, and an existing VAV system with total energy recovery (TER). In addition to the benefits of providing the right quantity of ventilation all the time to maintain IAQ at the better level, as prescribed by ASHRAE Standard 62, an annual energy savings of 20 percent was predicted when compared with the VAV system with total energy recovery.

Natural ventilation associated with shading techniques is an alternative way to reduce the use of expensive and environmentally harmful active systems, while providing summer thermal comfort and good indoor air quality. However, there is still a lack of knowledge concerning the design of such systems. The tool presented in this paper provides guidelines on natural ventilation and shading control strategies. This tool (called PHACES) has been developed under the MATLAB/SIMULINK environment by modelling an experimental device (HYBCELL) designed at the LASH/ENTPE laboratory.

This paper deals with tomographic techniques for two-dimensional spatially resolved concentrationmeasurements indoors. This represents a significant advance over the traditional point measuring method for mapping tracer gas and pollutants. Methods for recording of data are stressed as well as different types of tomographic reconstruction algorithms such as the Smooth Basis Function Minimization (SBFM) and the modified Low Third Derivative (LTDm) methods. Among the reconstruction algorithms available today, SBFM and LTDm are among the most promising.

A formulation to analyze ventilation duct system airflows employing, as the basic unknowns, the flow rates in the channel sections and the static pressures at the channel section ends is presented. This approach is called the PQ-formulation and the corresponding system equations are called PQ-equations. The system equations in the PQ-formulation are the engineering Bernoulli equations for the channel sections, the inlet and outlet pressure jump equations at the inlet and outlet nodes, the continuity equations at the junctions and the pressure jump equations at the junctions.

A methodology approach to simulate, by means of computational fluid dynamics (CFD) tools, a greenhouse equipped with a fan and pad evaporative cooling system is presented. Using the main aspects of evaporative cooling systems, in terms of heat and mass transfer, the flow and boundary conditions of the simulation model are identified taking into account both the external and internal climatic conditions. The crop (tomato) was simulated using the equivalent porous medium approach by the addition of a momentum source term.

The basis for room air distribution solutions in ventilating and air conditioning rooms is the calculation of velocities in air jets from supply outlets. To calculate velocities, the C-value of the air outlets must be known. The aim of this contribution is to acquaint readers with a non-traditional method for defining the C-value of an outlet from the angle of air jet expansion in the main jet zone, determined using interferometric visualization of the jet.