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ANSI/ASHRAE/IES Standard 90.1 requires vestibules to be installed in buildings in climate zones 3 through 8 based on building energy simulations with a series of assumptions which can be avoided using a new method of airflow and energy simulations. Instead of vestibules, it is believed that air curtains can also reduce infiltration and the associated energy loss through building entrances. Therefore, this study proposes a method to estimate energy savings from vestibule and air-curtain doors for two U.S. Department of Energy reference buildings in 16 U.S. climate zone locations in terms of national weighted average energy savings and a sensitivity study of different contributing parameters. [ABSTRACT FROM AUTHOR]

Extreme weather events, such as unusually high or low temperatures, and severe winds pose a threat to people and properties in cities. Managing the risk caused by these events requires effective climate adaptation policies to strengthen urban resilience to climate-related stresses. Simulation tools are needed for this purpose. In this work, an integrated CityFFD and CityBEM platform is used to study two extreme weather events in Montreal, Canada: the snowstorm of the century, and the urban heat island (UHI) in a hot summer day. CityFFD simulates local urban microclimate of a city to find the most vulnerable areas at extreme weather events, which are then used for the calculation of building thermal loads and indoor air temperatures using the CityBEM. The results show that integrated framework can produce high-resolution microclimate and building behavior under extreme weather events. [ABSTRACT FROM AUTHOR]

In this study, a dimensionless CFD analysis for the isothermal incompressible fluid flow in buildings is conducted to illustrate the Reynolds number similarity among different scales and the Reynolds independent phenomenon for the same scaled setup. For the similarity in different scales, the geometry similarity is required, and the Reynolds number is conserved by the boundary condition configurations to achieve the dynamic similarity, and a good match of the dimensionless results between scales can verify the dimensionless analysis procedure. For the simulations in the same scale, the dimensionless governing equations is further simplified and revealed the role of turbulence viscosity in Reynold independent phenomenon. A series of CFD simulation are conducted to study the distribution and evolution of turbulence viscosity with its relationship to achieve Reynolds independence. This paper develops a new method of justifying the Reynolds independence with CFD simulations, and this dimensionless CFD analysis method can be an important procedure for airflow pattern scaled experiments design and problem simplifications in urban and building airflows. [ABSTRACT FROM AUTHOR]

Multizone airflow network programs are increasingly used to study smoke movement during fires in buildings. Multizone programs often do not solve energy conservation equations, so temperatures ofrooms/zones need to be specified. The lack of energy models limits the capability of a multizone program for modeling building smoke movement, especially in shafts, where temperature distribution is often unknown. This paper introduces a multizone program with an added energy equation, CONTAM97R, with the focus of its application to simulations of smoke movement, especially in shafts of highrise buildings. First, CONTAM97R was validated by experimental data from a 1/3-scale building stairwell under fires, and verified by an analytical model of high-rise fires. The program was then used to model a 16-storey building with a fire located at the firstfloor. To model the building shaft by CONTAM97R, we proposed and compared two zoning methods, floor zoning strategy (FZS) and adaptive zoning strategy (AZS), when the shaft is with and without air infiltrations. It shows that the accuracy of FZS is inversely related to a dimensionless parameter, the temperature attenuation coefficient, a, but can be improved by increasing the number of zones dividing the shaft until the results do not depend on zone numbers. Compared to FZS, AZS obtains results ofsimilar level of accuracy but with fewer zones for the simulations. [ABSTRACT FROM AUTHOR]

Computer modeling of structural fires can play a significant role in simulating the development of a fire and the subsequent movement of smoke throughout the building. Computer programs have evolved to such an extent that they are able to predict where smoke will travel and to what extent it will contaminate various areas throughout the building such as fire escape stairwells and elevator shafts. Therefore, they can be employed to suggest modifications in the building construction, employment of building HVAC equipment, and use of pressurization fans in order to formulate a building life-safety plan that has a reasonable chance of reducing injuries due to smoke inhalation. In this work, the results provided by two computer programs that are capable of simulating smoke movement during building fires are compared for a simulated fire in a high-rise structure. Major differences in the formulation of the two programs are identified, and the differences in the predicted smoke movement results are explained. The temperature distribution throughout the building is shown to be a major factor in moving smoke within the building. Overall, there is reasonable comparison between the two computer predictions; however, large errors can result if the models employ unrealistic temperature distributions throughout the building structure. [ABSTRACT FROM AUTHOR]

District Cooling is an energy-efficient technology that can satisfy the cooling demands of regions with extremely hot climates such as the middle east. Designing and operating these plants requires accurate modeling of the existing cooling load created by the building stock connected to the central plant. During the design stage, building archetype models can be used for sizing district cooling load, whereas both the input and output uncertainties of these models have not been well addressed. This paper conducts a comparative analysis of two methodologies of building archetype development, develops an importance ranking for the input parameters of these models, and tries to quantify the uncertainty of the cooling energy output due to input value uncertainty. It develops a region-specific highrise residential archetype and compares it to the US DOE Prototype models. It also develops the parameter ranking using a global sensitivity analysis methodology. It is found that the most practical approach towards the development of building archetypes for a specific region is the development of region-specific models adapted to local practices rather than converting standard models for accuracy and computational cost considerations. It was also concluded that a set number of parameters are responsible for most of the model's output variability. Finally, this study demonstrated the usability of the building archetype models for the hot and arid climate. [ABSTRACT FROM AUTHOR]

Building energy modeling (BEM) involves many input parameters, including weather conditions, building geometry and properties, and building system and occupant information. Typical Meteorological Year (TMY) data are often used for the definition of weather conditions without considering urban microclimate variations. Compared to other inputs, the impacts of urban microclimate on BEM results are not adequately understood, and the literature also often presents inconsistent conclusions. In this paper, we conducted a sensitivity analysis (SA) to quantify the importance of urban microclimate and to identify the key parameters for the model output variations. Based on the Sensitivity Value Index (SVI), 13 BEM inputs were evaluated. It shows that the outdoor air temperature and wind speed play an essential role in building cooling energy usages in the hot and arid climate. Then, two approaches to estimating urban climate impacts on BEMs were compared in terms of outdoor air temperature, wind speed, and humidity in Lusail, Qatar by the 3D urban microclimate CFD model, City Fast Fluid Dynamics (CityFFD), and the simplified microclimate model, Urban Weather Generator (UWG). A comparative analysis of the simulation results to the local weather station measurements reveals the capabilities of the two approaches to estimating urban microclimate impacts on building energy performance. [ABSTRACT FROM AUTHOR]

The building sector accounts for nearly 40% of global energy consumption and plays a critical role in societal energy security and sustainability. A building energy model (BEM) simulates complex building physics and provides insights into the performance of various energy-saving measures. The analysis based on BEMs has thus become an essential approach to slowing down the process of increasing building energy consumption. The reliability and accuracy of BEMs have a high impact on decision-making. However, how to calibrate a building energy model has remained a challenge. Existing calibrations are often deterministic without uncertainties quantified. In this study, a new automated multi-module calibration platform, BIRBEM (Bayesian Inference on R for Building Energy Model), is developed using an R programming language for calibrating building energy models. The sensitivity analysis module determines the calibration parameters, and the building energy model is replaced by the developed meta-model module for the Markov Chain Monte Carlo (MCMC) process to save computing time. An application of a high-rise residential building case in a hot and arid climate was demonstrated. The coefficient of variation with a root-mean-square error (CVRMSE) value of the monthly total cooling energy consumption is 13.95%, which satisfies the monthly calibration tolerance of 15% required by ASHRAE Guideline 14. [ABSTRACT FROM AUTHOR]

Smoke inhalation is the leading cause of death during structural fires. In order to improve life safety during a fire, smoke must be managed and kept away from building occupants. In high-rise buildings, the problem of smoke movement is compounded by a strong stack effect that draws smoke into the vertical shafts within the building and contaminates the fire-escape stairwells as well as the elevator shafts. I f the smoke can be managed so that the stack effect can be used to advantage and egress routes can be maintained smoke free, then occupants will have a greater opportunity to avoid the effects of the smoke generated by the fie. This paper investigates a smoke control strategy that involves using the elevator shafts as a route ofsmoke extraction coupled with pressurizing the stairwells with sufficient fresh air to maintain smoke-free conditions in thefire escapes for the entire height of the building. The practicality and efficacy of this smoke management strategy is evaluated by employing a differential-network smoke management computer program that simulates the paths that smoke will take during a simulated fire. The computer program is verified by comparing its results with a computational fluid dynamics (CFD) software tool, Fire Dynamics Simulator, for a simple building geometry. Both programs compare well when a reasonable set of discharge coefficients is used to calculate the gas flows through various openings in the modeled building. The differential-network model quantifies the paths that the smoke will take and determines the smoke properties with a significant reduction of computational time when compared to the time required to provide the CFD simulations. Smoke generated by the fire will naturally tend to gravitate toward the elevator shafts, which exist at the lowest pressure within the building. Computer results show that large quantities ofsmoke can be directed away from occupants by controlling and exhausting the smoke through the top vent of the elevator shaft. If exhaust fans are used for smoke venting at the top of the elevator shafts and pressurization fans are used to maintain smoke-free conditions in the stairwells, then a prudent fire safety plan will result. The program output is used to quantify the amount of elevator exhaust and stainvell pressurization that is necessary to achieve safe conditions during the fire for various building geometries and fire conditions. [ABSTRACT FROM AUTHOR]