English

Current methods for designing exhaust stack height and exit velocity are based on avoiding contamination of the roof, walls, and nearby ground surface of the building on which the stack is located. Usually, no account is taken of the effect of adjacent buildings that add turbulence and increase dispersion if they are located upwind and may be contaminated themselves if they are downwind of the emitting building.

This paper evaluates the performance of traditional displacement ventilation systems for small offices, large offices with partitions, classrooms, and industrial workshops under U.S. thermal and flow boundary conditions, such as a high cooling load. With proper design, displacement ventilation can maintain a thermally comfortable environment that has a low air velocity, a small temperature difference between the head and foot level, and a low percentage of dissatisfied people.

A three-dimensional computational fluid dynamics (CFD) analysis has been used to predict airflow patterns in laboratory fume hoods. The simulation includes bypass fume hood primary operational features including the top and bottom bypasses, front airfoils, and rear-slotted baffles. All results were validated experimentally, and the simulation was found to adequately predict fume hood airflow patterns. The results indicate that fume hood flow patterns are highly dependent on inlet flow boundary conditions so that the computation must include the near field room airflow.

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.

Sealed attic construction, by excluding vents to the exterior, can be a good way to exclude moisture-laden outside air from attics and may offer a more easily constructed alternative for air leakage control at the top of residential buildings. However, the space conditioning energy use and roof temperature implications of this approach have not been extensively studied. A computer modeling study (Rudd 1996) was performed to determine the effects of sealed residential attics in hot climates on space conditioning energy use and roof temperatures.

NFPA Standard 92B presents computational methods for determining the position of a smoke layer in a large-volume space. Although NFPA 92B is a guide to smoke management design, the methods have been adopted, with certain modifications, by model building codes and are mandated for use in atriums and large-volume spaces. This paper makes use of a recently developed CFD fire model to assess the NFPA 92B calculation methods. A total of 13 simulated tests were conducted.

Measured contaminant and heat removal effectiveness data are presented and compared for a 3: 1 scale model room, which represents a smoking room, lounge, or bar with a two dimensional airflow pattern. In the experiments, heat and tracer gases were introduced simultaneously from a source to simulate a prototype smoking room. High-side-wall and displacement ventilation schemes were investigated, and the latter employed two different types of ceiling diffuser, low velocity slot and low-velocity grille.

The large heat loss from Passive-stack ventilation (PSV) systems quite often makes natural ventilation systems unattractive and it is therefore desirable to implement heat recovery in PSV stacks. As the stackpressure is usually about a few Pascal, it is crucial that the heat recoveryunit used in a PSV system produces even lower pressure loss, which is extremely difficult to achieve with the conventional plate heat exchangers. This work is concerned with an a low pressure-loss heat recovery device based on heat pipes.

This paper gives an overview of the European NatVent® project on'Overcoming Technical Barriers to Low Energy Natural Ventilation in Office Type Buildings in Moderate and Cold Climates'. The project was targeted at countries like the UK with low winter and moderate summer temperatures where summer overheating from solar and internal gain can be significantly reduced by low-energy design and good natural ventilation.

A concept design is proposed for a new generation of superstores, which addresses the global problem of Carbon Dioxide emissions and the demand of retail traders for increasing economies in energy. The new superstore building has been engineered from the ground up to incorporate the current best practice in environmental design. With application of suitable energy conservation technologies it is proposed that this approach will provide a retail environment fit for the next millem1ium and achieve a 50% reduction in Carbon Dioxide emissions over a conventional supermarket.