G. T. Bitsuamlak

• PhD, PEng, F CSCE
• Director WindEEE Research Facitlties at Western University

Building natural ventilation is a sustainable approach to reducing energy use and emissions from buildings by minimizing reliance on energy-intensive systems. Computational Fluid Dynamics (CFD) simulations are often used to predict natural ventilation, enhance building design, and improve indoor air quality. However, CFD simulations are time-consum...

Buildings are major contributors to global carbon emissions, accounting for a substantial portion of energyconsumption and environmental impact. This situation presents a critical opportunity for energy conservationthrough strategic interventions in both building design and operational phases. Artificial Intelligence (AI)has emerged as a transforma...

Successful application of large-eddy simulation for wind load evaluation of ground-mounted solar panels (GMSPs) requires rigorous benchmark validation. A validation campaign exploring several LES parameters and wind tunnel model details is underway. This study is carried out on a 25◦ tilt isolated GMSP with wind tunnel data as a target. The main LE...

Smart building digital twins represent a significant paradigm shift to optimize building operations, thereby reducing their substantial energy consumption and emissions through digitalization. The objective is to virtually replicate existing buildings’ static and dynamic aspects, leveraging data, information, and models spanning the entire life cyc...

The interflat cross-contamination of air pollutants such as coronavirus disease 2019 (COVID-19) in built environments has become a growing concern. This study investigates the effect of the geometrical details of building facades on wind-induced airborne pollutant transmission routes in high-rise buildings. Parametric studies of different external-...

Active yaw control (AYC) is a promising technique to improve the power performance of wind farms. In this work, a novel analytical model for yawed wind turbines, considering the effects of yaw angle, turbulence intensity and thrust coefficient, is developed to predict the velocity deficit and the wake deflection. The model is derived based on the m...

Wind load evaluation on buildings using large-eddy simulation (LES) poses several critical challenges. The most notable ones include accurately reproducing the approaching atmospheric boundary layer flow conditions and modeling massively separated flows around buildings. This study investigates the capability of LES for predicting cladding and over...

In austere environments, such as northern regions, remote communities face many challenges, such as permafrost warming and significant infrastructure deficits. With the increasing demand for soil stabilization methods beneath structures, adapting building designs has become vital for a sustainable and resilient future in the northern climate. This...

In this study, a BIPV/T system coupled with heat pump is proposed where the heat extracted from the BIPV is used to drive the heat pump. The energy saving potential is assessed for a case where the heat extracted is used for domestic hot water heating. An analytical model of the BIPV/T concept is developed using CFD and implemented in EnergyPlus to...

Natural ventilation is an essential element of sustainable buildings as well as a promising solution for mitigating indoor air quality (IAQ) issues such as those related to the spread of COVID-19. The current study analyzes wind-driven cross-ventilation efficacy for a low-rise residential building with complex geometry and internal partitions consi...

The wind load provisions for gabled roofs with a slope of 27° < α < 45° in the National Building Code of Canada (NBCC) were derived from wind tunnel studies conducted in the 1970s. The coefficients have remained basically unchanged until this time. The paper presents the results of full-scale measurements and wind tunnel experiments to verify the n...

The presentation focused on the need and requirements of verifying and validating LES for predicting cladding and overall loads and responses of tall buildings. The work tried to address some of the critical challenges in LES-based wind load evaluation, adhering to the rigors of the current wind engineering practice. At the end of the presentation,...

Smart-building digital twins aim to virtually replicate the static and dynamic building characteristics through real-time connectivity between the virtual and physical counterparts. The virtual replica of the building can then be leveraged to monitor the current state, predict the future state, and take proactive measures to ensure optimal operatio...

The accuracy of Large-Eddy-Simulation (LES) in modeling wind loads, especially components and cladding loads, does not currently fulfill its potential. The lack of extensive consideration for wind loading requirements and their direct influence on LES duration and mesh size are identified as research gaps. This study presents a validation metric fo...

Failure of roof-mounted equipment in extreme wind events such as hurricanes is a significant contributor to wind-related property loss. Proper understanding of the nature and magnitude of wind-induced loads on these structures is essential to ensure their safety during severe storm conditions. Previous studies showed that wind loads on roof-mounted...

The current wind load provisions for low-slope roofs in the NBCC were established in the 70 s with wind tunnel experiments using analog data technology. These coefficients have remained almost unchanged. As the wind pressure measurement tools have significantly improved during the past 50 years, verification of the original pressure coefficients is...

One of the challenges in realistic numerical urban micro-climate modelling for wind, heat transfer, and building energy simulation applications is the complexity of urban topology and complex building geometries. This paper presents a deep learning modelling for building footprint polygon extraction from satellite imagery that is integrated with Li...

In recent years, engineered wood products, such as cross-laminated timber (CLT), nail-laminated timber, dowel-laminated timber, and glued laminated timber (glulam), have routinely been used to construct the gravity and lateral load-resisting systems within tall timber buildings. Using timber load-resisting systems in tall buildings results in struc...

Condensation on the surface of an Air Handling Unit (AHU) can interfere with energy efficiency, air quality and cause damage to the mechanical equipment and building. The fundamental calculation of condensation is complex due to the intricate interaction between the AHU surface and its environment. Realistic modeling of conduction through the AHU w...

Analytical modeling of canopy layer wind flow is commonly used to study local air transport around plant or building canopies. The models also help in the estimation of canopy boundary drag contribution for the atmospheric scale flow. Existing canopy layer airflow models exhibit limitations, especially for low packing density scenarios. In the curr...

In 2050 it is estimated that more than twice as many people will be urban dwellers compared to those living in rural areas. To accommodate this ever-growing urban population, designing cost-effective tall buildings satisfying structural strength and serviceability requirements is crucial. For tall buildings, wind is often the governing lateral load...

Wind-turbine wakes over two-dimensional (2D) hills with different slope gradients are systematically investigated using large-eddy simulation (LES) with wind turbine parameterized as actuator disk model (ADM) and hilly terrain modeled by immersed boundary method (IBM). The chosen hill models represent typical hilly terrains with and without flow re...

Recently developed Large Eddy Simulation (LES) tools, such as inflow generators, boundary conditions, and other utilities, primarily focus on tall building wind load evaluations. It is essential to evaluate these computational tools for wind load evaluation with some of the unique characteristics of low-rise buildings into consideration. For exampl...

The effect of varying rib geometry on the turbulent natural convective heat transfer coefficient in a BIPV air channel was assessed numerically. The CFD model was validated with experimental data from the literature to within reasonable accuracy. The study investigated parameters such as the rib shape, dimensionless rib height (e/D), dimensionless...

Overheating in BIPV/T applications is a concern due to its negative impacts on the electrical conversion efficiency of the solar cells. Forced air cooling can be an effective thermal management strategy. However, its effectiveness is limited by the thermal resistance associated with the boundary layer formation on the walls of the air channel. The...

The lateral strength and stiffness requirements due to wind loads usually govern the design of tall buildings. The current building codes in the US, Canada, and Europe recognize the first significant yield point as an ultimate limit state. Consequently, the current design practices ignore the plastic capacity of structural systems in the nonlinear...

Part I of the two companion papers postulated and proved the capability of self-centering systems in controlling the wind-induced damage accumulations due to long-duration along-wind loads. The present Part II paper demonstrates the benefits of ductility-based wind design in terms of economics and safety through structural reliability analysis. Ini...

Current numerical aerodynamic wind turbine blade models-models that calculate the aerodynamic loads on a blade based on the incoming wind-are generally computationally intensive. However, a surrogate aerodynamic blade model consisting of a neural network (NN) trained on high-accuracy data should be capable of achieving both high accuracy and fast c...

Large-eddy simulations (LES) have been conducted in OpenFOAM to estimate wind loads on 3 m cube shaped roof-mounted equipment for seated and three elevated configurations. The study aims to interpolate existing experimental data for different equipment elevations. The LES results were first validated against wind tunnel data using mean as well as f...

Window sizing and configuration can have a significant influence on building energy consumption. Window selection often has a conflicting objective on heating, cooling, and lighting performance. The smaller window performs better on controlling heat loss in winter and solar heat gain in summer, while the larger window performs better on providing v...

Unmanned Aerial Vehicle (UAV) swarms are promising solutions to conduct different military and commercial missions. However, highly varying environmental factors such as wind make the UAVs unable to maintain the minimum safe distance between each other, and the UAVs at the edge of the swarm more vulnerable to connectivity loss from the swarm. The p...

The generation of inflow turbulence is the first necessary step to conduct a successful large-eddy simulation (LES) of atmospheric boundary layer (ABL) flows. It is required that the generated inflow turbulence is divergence-free and satisfies essential target statistical properties, including the two-point statistics of the flow described by the c...

In this work, a 10-story uncoupled (10S-U) hybrid seismic force resisting system, consisting of cross-laminated timber (CLT) walls and reinforced concrete (RC) beams, is considered. Required design ductility factor Rd, in congruence with the National Building Code of Canada, was developed using FEMA P695 collapse risk procedure. Two trial Rd factor...

The impact of the ventilation cavity design on the energy performance of the rainscreen wall assembly was numerically investigated in CFD. The ventilated cavity design parameters considered were the cladding material type (i.e. Fibre cement, brick, and metal cladding), the sheathing membrane emissivity coefficient (i.e. 0.1–0.9), the ventilated cav...

Governments around the world have implemented measures to slow down the spread of COVID-19, resulting in a substantial decrease in the usage of motorized transportation. The ensuing decrease in the emission of traffic-related heat and pollutants is expected to impact the environment through various pathways, especially near urban areas, where there...

Electricity consumption is accelerating due to economic and population growth. Hence, energy consumption prediction is becoming vital for overall consumption management and infrastructure planning. Recent advances in smart electric meter technology are making high-resolution energy consumption data available. However, many parameters influencing en...

The use of timber panels to construct the lateral and gravity load resisting systems of tall mass-timber buildings makes them lightweight and less stiff than buildings made from conventional construction materials. As a result, frequent exposure to wind-induced oscillations could cause discomfort to the occupants. This study examines the dynamic re...

The buildings in northern Canada have unique climatic and environmental challenges, and therefore, the need for innovative building design has become a vital requirement in a sustainable and resilient future. This study proposes a framework to integrate building information modeling (BIM) and computational fluid dynamics (CFD) analysis to study mic...

One of the next frontiers in structural wind engineering is the design of tall buildings using performance-based approaches. Currently, tall buildings are being designed using provisions in the building codes and standards to meet an acceptable level of public safety and serviceability. However, recent studies in wind and earthquake engineering hav...

Current real-time hybrid tests of wind turbines are limited by the use of simplified aerodynamic blade models due to time constraints during testing. Research has shown that these techniques can introduce notable error into wind load predictions, and thus exist as a limitation for the further development of this avenue of research. However, neural...

Presentation of conference paper: https://www.researchgate.net/publication/343903187_Evaluation_of_a_neural_network-based_surrogate_aerodynamic_wind_turbine_blade_model/

nstallation of open-joint roof paver systems with pedestals on flat roofs leaves a cavity between pavers and roof deck, allowing the development of cavity pressure. The cavity suction on roof pavers reduces the net wind uplift and overturning. This study conducted pressure measurements of the paved roof of a large-scale building model using the Uni...

ASHRAE Standard 90.1 provides a useful guideline for the Window-to-Wall Ratio (WWR), stating that “the total vertical fenestration area shall be less than 40% of the gross wall area” However, different window configurations with the same WWR can perform thermally differently. In this paper, the effect of window configurations on the convective heat...

Robust semi-active vibration control of wind turbines using tuned mass dampers (TMDs) is a promising technique. This study investigates a 1.5 megawatt wind turbine controlled by eight different types of tuned mass damper systems of equal mass: a passive TMD, a semi-active varying-spring TMD, a semi-active varying-damper TMD, a semi-active varying-d...

Numerical study of the behaviour of wind turbine blades can be quite challenging due to the complex 3D aerodynamic effects that occur around the blade. In an attempt to study the role this behaviour plays on the overall structural response of the wind turbine, a numerical parametric study assessing the impact of two blade-modelling practices was pe...

Building information modeling (BIM) can be considered a collaborative design process that allows all project stakeholders in different disciplines to contribute during the design phase of a construction project. However, interoperability issues between wind, structural engineering tools, and BIM design authoring software platforms have acted as a b...

Current external convective heat transfer coefficient estimation methods are known to introduce significant uncertainty in energy consumption evaluations for building with complex surrounding conditions. In this study, the impact of built area density (aggregation or rarefaction) on convective heat transfer from buildings is numerically investigate...

With the rapid development of the wind energy industry many wind farms have been constructed in regions prone to earthquakes and strong winds, which sometimes cause serious structural vibration problems for wind turbines. This paper details the development of a scissor-jack braced viscous damper system (VD-SJB) to suppress excessive vibration of th...

This report includes a seismic and wind design for RC-timber hybrid structure consisting CLT walls, glulam columns and RC beams. The report can be downloaded from: http://hdl.handle.net/2429/71592

The building codes and standards in many parts of the world, including regions with a high risk of tropical cyclones, recognize the first significant yielding point as an ultimate limit state. The main argument used in favor of linear-elastic analysis approach is its presumed ability to avoid asymmetric yielding and the subsequent damage accumulati...

The lateral strength and stiffness requirements due to wind loads usually govern the design of tall buildings. The building codes in the U.S.A, Canada, and Europe recognize the first significant yield point (i.e., linear-elastic design) as an ultimate limit state, which could result in conservative and uneconomical design of the tall buildings. Thu...

This paper presents an overview of wind turbine research techniques including the recent application of hybrid testing. Wind turbines are complex structures as they are large, slender, and dynamic with many different operational states, which limits applicable research techniques. Traditionally, numerical simulation is widely used to study turbines...

The energy consumption analyses of high-rise buildings have some fundamental limitations that include the treatment of building size, changes in microclimate parameters with altitude, and the uncertainties associated with the existing building façade convective heat transfer coefficients correlations (CHTC). This study investigates the effects of t...

In coastal regions, it is common to witness significant damages on low-rise buildings caused by hurricanes and other extreme wind events. These damages start at high pressure zones or weak building components, and then cascade to other building parts. The state-of-the-art in experimental and numerical aerodynamic load evaluation is to assume buildi...

In recent years, there is an urban architectural evolution towards significant use of glazing in high-rise buildings. Windows play a critical role in moderating the elements of the climate. Although good for outdoor viewing and daylighting, glazing has very little ability to control heat flow and solar heat gain. As a result, about 20 - 40% of the...

Buildings use about 40% of the global energy and emit approximately 33% of the greenhouse gas emission. Realizing the significant amount of energy consumption in buildings, it is essential to investigate the accuracy of the estimation of energy consumption predictions by Building Energy Simulations (BES) programs at the early design stages to achie...

This paper studies the structural responses and failure modes of a 1.5-MW horizontal-axis wind turbine under strong ground motions and wind loading. Ground motions were selected and scaled to match the two design response spectra given by the seismic code, and wind loads were generated considering tropical cyclone scenarios. Nonlinear dynamic time-...

Numerical simulation of tornado-like vortices, like those produced in experimental facilities, poses many challenges. This is attributed to the complexity of vortical flow-field and the common practice of directly using the geometric dimensions and configuration of physical elements like guide vane angle, ceiling height, etc. of experimental simula...

In this paper, we examined the effects of extreme tornadic wind loads on mass-timber buildings. In general, mass-timber buildings utilize pre-engineered wood panels to form their main gravity and lateral load resisting systems. The lightweight nature of timber makes these types of emerging buildings lighter and more flexible than buildings made fro...

The dependency of wind forces and responses on the outer shape of tall buildings provides a unique opportunity to reduce wind effects through the aerodynamic optimization of the outer shape. The current study presents a multiobjective aerodynamic optimization procedure (AOP) by introducing horizontal openings to reduce wind load. The adopted method...

This paper investigates the impacts of external shadings on the convective heat transfer rate of a high-rise building. The convective heat transfer coefficient (CHTC) is evaluated using high-resolution 3D computational fluid dynamics simulations. Thus, as the depth of the shading element increases, reduced values of CHTC were obtained. Except at th...

A steady,3-D, flow model was used with a RANS formulation of SST -k-W turbulence model. At the inlet of the domain, an atmospheric boundary layer (ABL) was imposed with different wind speeds of U (10) =1,2,3,4 and 5 m/s. To resolve the entire boundary layer, including the viscous sublayer, a high-resolution (LRNM) grid with a cell center at a minim...

Tall mass-timber buildings utilize engineered wood panels to form their main gravity and lateral load resisting systems, which makes them lighter and very flexible. As a result, frequent exposure to excessive wind-induced vibrations can cause occupant discomfort and unserviceability due to horizontal floor acceleration and excessive deflection. The...

The latest architectural trends demand an extensive use of glazed curtain walls running from building floor to ceiling. While glazing poorly controls the heat flow, it is important for viewing, daylighting, and solar design features. In order to evaluate building energy consumption accurately, knowledge of convective heat transfer coefficient (CHTC...

The effects of steep and shallow hills on a stationary tornado-like vortex with a swirl ratio of 0.4 are simulated and quantified as Fractional Speed Up Ratios (FSUR) at three different locations of the vortex with respect to the crests of the hills. Steady state Reynolds Averaged Naiver Stokes (RANS) equations closed using Reynolds Stress Turbulen...

In this study, wind load on complex roofs of low-rise building is evaluated using LES. An existing house for which wind tunnel test data was provided by the Boundary-Layer-Wind-Tunnel Laboratory at Western University. The flow condition of the wind tunnel was simulated by applying artificially generated inflow for LES. Mean and r.m.s values of pres...

The convective heat transfer coefficients (CHTC) used by building energy simulations are primarily derived from the experimental and numerical analysis carried out on low-rise buildings with smooth façade surfaces. Therefore, the use of the existing CHTCs for high-rise buildings and non-smooth facades may produce inaccurate results. To investigate...

Low-rise buildings are vulnerable structures to wind damage during hurricanes, typhoons and extreme wind events. Various experimental and numerical studies were conducted on low-rise buildings to evaluate and control the wind-induced loads. These studies considered wind to be acting on the building external walls. This assumption can only be applic...

The need for sustainable buildings has become more evident to curb the building's environmental footprint through passive designs, and efficient utilization of energy and materials. The aim of this study is to investigate the impact of building form, orientation, shading, and building envelope on energy consumption/cost of a residential building. B...

The rapid growth of urban population and the associated environmental concerns are partly influencing city planners and construction stakeholders to consider "Sustainable Urbanization" alternatives. In this regard, recent urban design strategies are entertaining the use of "tall timber buildings." Generally, tall mass-timber buildings (MTBs) utiliz...

Since wind is a governing design load for various structures, an accurate simulation of the aerodynamics will reduce the uncertainty associated with wind load evaluation on structures, and consequently their cost. Thus, highly accurate and reliable computational fluid dynamics (CFD) modeling is required to simulate and evaluate the wind behaviour f...

Poster presented on Mar. 23, 2018 at the "Modeling the effects of natural hazards on the built-environment: Bringing together multi-hazard and high-performance computing communities" workshop organized by Professor Girma Bitsuamlak at Western University.

In a cold winter, outdoor environmental conditions primarily influence the indoor surface temperature of building windows. This leads to a temperature gradient in the indoor environment which induces a downdraft affecting the thermal comfort of occupants. This phenomenon is sensitive to the configuration and location of windows. in this paper, the...

This paper reports the first aero-elastic test conducted under a scaled downburst wind field at the WindEEE dome facility at the University of Western Ontario, Canada. The main purpose of the test is to assess the dynamic response of a multi-span transmission line. The study starts by providing a characterization of the downburst wind field produce...