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.
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.
Many methods of estimating energy savings from measured weather-dependent energy consumption data attempt to compensate for varying weather conditions between the pre- and post-retrofit periods by identifying an empirical model of pre-retrofit energy consumption and outdoor air temperature. Even though the pre-retrofit model may include a balance-point or change-point temperature, savings determined using this method implicitly assume that the indoor air set-point temperature and internal heat gains are the same during the pre- and post-retrofit periods.
The goal of this work is to better understand the influence of window U-factor and solar heat gain coefficient on residential space heating and cooling energy use in the United States. We calibrated our simulation models with residential energy use data and evaluated the affect of window U-factor and solar heat gain coefficient on space heating and cooling energy use. U-factor and solar heat gain coefficient have a comparable impact on heating energy use, whereas U-factor has a minor impact and solar heat gain coefficient has a strong impact on cooling energy use.
A small commercial building was monitored before and after energy-saving retrofits to study the impact of retrofits upon ventilation rates, humidity, building pressure, and air-conditioning energy use. Duct airtightness testing identified severe duct leakage as a significant source of uncontrolled airflow. Differential pressure and infiltration measurements using tracer gas indicated an attic exhaust fan as another significant source of uncontrolled airflow. Duct repair resulted in a 31% drop (30.5 kWh/day) in cooling energy and an increase in relative humidity from 72% to 76%.
Recent ASHRAE forums have revealed an increased interest in information and guidance relative to designing and applying ventilation systems for areas where smoking is permitted. There are few data currently available through ASHRAE for the engineer challenged with designing a cigar bar, a smoking lounge, or a bar or restaurant with smoking permitted. This paper applies laboratory data about the acceptance of environmental tobacco smoke to real-world applications.
ASHRAE currently provides little practical information for optimizing the design of a cigar or smoking lounge, although recent ASHRAE forums have indicated an increased interest in this area. This paper provides a summary of the measurement of environmental tobacco smoke (ETS) from cigarettes or cigars, the manner in which ETS concentration varies with rates of smoking and ventilation, and the relationship between ETS concentration and indoor air quality.
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.