Methodology for the Evaluation of Natural Ventilation in ... - Cham

This novel reduced-scale air modeling method developed for use in evaluating natural ventilationin buildings provides more detail than current water modeling techniques and can enhancenumerical simulations. This methodology shows detailed temperature distribution and the mainairflow patterns while behaving more like a typical building with radiation and heat loss.Although there can be difficulties with the monitoring equipment and initial boundaryconditions, modeling using air as the fluid provides accurate results. This is due to the thermalproperties that are conserved when using air, such as radiation and thermal diffusivity. Usingreal fluids in physical models allows the flow to re-circulate and separate. The conservationequations are automatically included in the analysis with physical modeling with air becausethere are no approximations or missing terms. The experimental work can not be adjusted to tryand match theory, whereas with simulation methods, a slight change in a variable can be sued toobtain a better match of results. Reduced-scale air models may not be fast or flexible enough forsensitivity analyses, but they can enhance the tools that are used to do so. There was goodagreement between the full-scale CFD simulations in terms of temperature distribution andairflow patterns when compared to the full-scale prototype. Additionally there was goodagreement when comparing the reduced-scale air model to the reduced-scale CFD simulation.The two CFD simulations provided good correlation between the full- and reduced-scaleversions as well.8.3 Future Research WorkThis research provides the foundations for reduced-scale air modeling as a means to predict thetemperature and airflow in naturally ventilated buildings. It is by no means exhaustive. Thereare areas for further work, both with the current configuration to understand better the prototypepassive design, and with other configurations of passively ventilated buildings that could benefitfrom additional analyses using the reduced-scale model technique.For the current configuration, experiments with fan-assisted airflow through the stacks wouldhelp not only in improving the building performance, but also in better understanding atrium fansas a design characteristic. Understanding the effectiveness of the atrium fans will reduce theoccurrence of uncomfortably warm temperatures in the upper floors, which is a commonproblem in naturally ventilated buildings. Altering the height of the atrium stack and therebyincreasing the buoyancy effect, is an additional design strategy that could be implemented in thereduced-scale model.The open floor plan connected to a central atrium is a common commercial building layout, butis not the only one in use. Testing configurations other than that used for the reduced-scalemodel, the prototype potentially could improve building design configurations as well. Thismodeling technique is a method for evaluating different configurations and design characteristicsto understand the flow patterns and temperature distributions in full-scale buildings throughdimensional analysis and similitude. The results can then be used in formulating tools andenhancing numerical simulations to predict more accurately natural ventilation in commercialbuildings.Finally, the airflow visualization methods could be improved. The techniques developed as partof this methodology were useful in determining airflow movement from one zone to another aswell as how the zone interacted with the atrium. Tracing the streamlines, akin to what CFD165