Advanced and Robust Analysis of Wind Effects
Advanced and Robust Analysis of Wind Effects
Large construction projects are challenging enough without having to now navigate the recent increases in the cost of materials and labour. The cost of construction is one of the biggest challenges that developers face today, especially given the current global economic conditions. However, there is a little-known solution that can help to reduce the cost of construction typically in the order of 10-20% without impacting the design or quality of the building. The solution is performance-based wind design, specifically through wind tunnel testing and the adoption of advanced data analysis and probabilistic methods, which can help in further optimise the design of structure and façade, reduce material waste, and improve sustainability, all of which has a material impact on reducing embodied carbon associated with a project.
Figure 1. Sample Projects Tested in Windtech’s Boundary Layer Wind Tunnel
The prescriptive code-based design approach can be limiting, as it does not allow for flexibility and innovation. It also does not consider the specific wind loads and environmental factors that a building may encounter in its context. Hence the various committees that govern code content deliberately make them conservative and limit their scope to the typical building.
Wind tunnel testing is by its nature a performance-based design tool that provides an alternative option to the code-based design approach. It is a process that involves placing a scale model of an “as-designed” building in a wind tunnel within a model of the surrounding buildings, simulating the wind flow for multiple wind angles, and post-processing the data to determine full scale loads on structure and cladding. It does not need to adopt unnecessary levels of conservatism as it tries to produce wind effects that represent reality. However not all wind consultants are the same, as they adopt different methods for loads on structure and cladding, in addition to assessing the building performance under normal serviceability conditions. This aspect alone can make the difference between a 10% or 20% construction cost saving.
Aaron Lefcovitch, a Director of Windtech based out of the Singapore office explains “When, on occasion, the response of a building or structure to wind action has been compared between two of more wind consultants, it has been noted that a major source of difference has often turned out to be the way the wind consultant deals with directionality. Several methods have been proposed to deal with directionality, however some of these methods which are widely used, have significant limitations that could result in substantially under or over predicting the wind loads on the structural system or facade cladding. Windtech uses the multi-sector method (for more information see: Directionality: A key source of discrepancy between the results of Wind Consulting Companies | LinkedIn) which has been recognised by the ASCE Manual of Practice No. 143 (Design and Performance of Tall Buildings in Wind) as being the most sophisticated method of accounting for directionality with the least amount of approximation (and conservatism). Windtech is the first wind engineering firm to implement the more rigorous multi-sector analysis technique more than a decade ago. In doing so, we have been doing our part by bringing advanced technologies to the market which have a material impact on cost, design efficiency and sustainability, though the use of more pure performance-based design methods. Applying the latest advances in the wind engineering industry remains to be one of the core focuses of the team at Windtech, and we continue to develop these technologies on an ongoing basis to serve our clients”
Figure 2. Sample Projects Tested by Windtech
Wind tunnel testing is a useful tool for tall building design because it provides crucial information on how a building will respond to wind loads, particularly under normal serviceability wind conditions. Codes and Standards often require buildings to meet specific criteria for deflection and acceleration, and if these criteria are exceeded, additional costly structural rework or auxiliary devices like dampers may be required to bring the building accelerations within permissible limits. Wind tunnel testing also ensures that some of these costly measures are not implemented into a building unnecessarily. In combination with Windtech’s advanced multi-sector method we can assist the design team in eliminating the unnecessary costs, allowing the opportunity to optimise the structural design and minimize material waste and/or damping systems that may in fact not be required. This all has a material impact on also reducing the risk of costly delays which would also impact a projects bottom line, assuming the building does not comply from a performance point of view.
Figure 3. Sample Special Projects Tested by Windtech
Tony Rofail, a Director of Windtech based out of the Sydney office adds that “wind tunnel studies generally result in 10-15% reduction is cost of a major development up to lockup stage (façade and structure). However, a study conducted of over 55 typical tall building projects indicated that the more rigorous Multi-Sector analysis technique was not only more accurate from a loads and dynamic responses point of view, but in fact resulted in an additional 5-10% saving in the cost of the structure and façade. Even greater savings can be achieved for the very tall or slender developments (however many of these would tend to fall outside of the scope of wind loading standards anyway). A small investment in the use of rigorous techniques pays significant dividends down the track, and we are not talking 10% or 20% – it is typically in the order of 2,000% to 5,000%!. This is why the more successful developers don’t think twice about commission Windtech”
If you are working on any projects that could benefit from the capabilities presented in this article, please reach out to our regional office via our Contact Us page.
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Wind studies for building construction projects can take on different forms depending on their purpose. Some studies aim to ensure the structural integrity of tall buildings against extreme weather conditions like typhoons or hurricanes. Others may focus on mitigating the impact of wind from a serviceability point of view i.e. wind induced noise and wind driven rain.
One of the most frequently conducted wind studies is the assessment of Pedestrian Pedestrian Wind Environment Impacts. These studies are crucial in ensuring the safety and comfort of pedestrians in critical outdoor areas within the urban landscape. They do this by identifying areas that are subject to adverse wind conditions including the mechanisms behind them. This then allows for the development of treatment strategies to ameliorate the impacts which impact the design. This article aims to offer insights on how to minimise the risk to project budgets and timelines as a result of these necessary and helpful studies being implemented as part of the design process.
Pedestrian Wind Environment Analysis on a project in London
Known as “Pedestrian Microclimate” or “Pedestrian Wind Comfort” studies, the assessment is essential for ensuring safe, comfortable, and functional outdoor spaces for pedestrians. Windtech, with decades of experience in Pedestrian Wind Environment studies, recognises that working collaboratively with clients and keeping them informed about best practices is vital for meeting and exceeding expectations.
So, when conducting Pedestrian Wind Environment studies what are some tips to minimise the risk of wind mitigations impacting your project’s timeline and budget. Here are our top three:
At Windtech, we offer preliminary pedestrian wind environment assessments that can identify high-risk areas and advise on the best approach based on the location, timeline, and specific project requirements. Depending on the project size and complexity, we may recommend a desktop assessment or a CFD study.
Getting an early-stage assessment allows us to assist in developing integrated, elegant, and cost-effective wind mitigation strategies that are harder to implement at later stages of the design process. After agreeing on a strategy, we may suggest preliminary mitigation testing, usually through CFD, to accurately quantify the effect of the proposed strategy and make any necessary adjustments. This approach helps to streamline the design process and ensure a successful outcome for your project.
An example of wind mitigation being tested using a CFD model
At Windtech, we believe in identifying potential high-risk areas in your development as early as possible, so you can integrate effective wind mitigation measures without compromising on the overall design. By contacting us during the initial stages of your project, we can provide you with a competitive scope, fee, and timeline, and guide you towards the appropriate guidelines.
We understand the importance of time in any project and take pride in developing customized wind mitigation solutions that are not over-specified. To ensure a successful outcome, we recommend starting with a detailed wind tunnel and/or computational fluid dynamics (CFD) study as soon as the building envelope has been set. This allows for sufficient time for at least one round of wind mitigation tests, if needed, after we provide our initial report.
We acknowledge that time constraints are always a challenge, but engaging with us early in the design process will make the entire process less stressful and lead to a better overall design outcome. Request a quote today and allow us to help you mitigate the potential risks of wind impact on your development.
Pedestrian Wind Environment Wind Tunnel Model Showing Probe Locations
Although wind engineering may seem simple, acquiring a deep understanding of how wind interacts with buildings and affects occupants can take years or even decades of experience. However, once you acquire this knowledge, you’ll be able to identify potential risk areas and recognize primary flow effects that could impact your project’s development.
To start, we suggest determining the predominant wind direction in the area and analysing the impact of downwash and funnelling on the building. This will help you gain a comprehensive understanding of how wind can affect the development of your project.
Downwash Funnelling
A simple guide (which discusses other potential wind mechanisms) is provided here: https://windtechconsult.com/20-seriously-effective-wind-mitigation-strategies-for-your-next-project/
Alternatively, why not schedule a presentation with one of our team members? With offices in Sydney & Melbourne, Australia, London, UK, and Mumbai, India. New York & Miami, USA, Dubai, Hong Kong & Singapore, we guarantee to support you wherever you are based. Get in touch here.
It is not uncommon for clients to approach us with the belief that their project has no wind issues because they have already conducted a basic CFD analysis that did not identify any problems. However, we have seen instances where off-the-shelf CFD software or studies undertaken with unproven methodologies have led to results with a significant discrepancy of 40-50% against wind tunnel test results. This discrepancy can lead to a false sense of confidence in the scheme’s wind environment performance, which could result in an unpleasant surprise during the final, detailed wind tunnel study assessment. Therefore, it is essential to be cautious of the quality of the CFD analysis and to validate the methodology before relying on its results.
We recommend reviewing further information on benchmarking and validation of CFD simulations applied to the pedestrian wind environment around buildings, which can be found in the links provided below.
1. AIJ guidelines for practical applications of CFD to pedestrian wind environment around buildings: https://www.sciencedirect.com/science/article/abs/pii/S0167610508000445
2. AIJ Benchmarks for Validation of CFD Simulations Applied to Pedestrian Wind Environment around Buildings https://www.aij.or.jp/eng/publish/vsapwe2016e_tb_of_cont.pdf
3. Best Practice Guideline for the CFD Simulation of Flows in the Urban Environment: COST Action 732 Quality Assurance and Improvement of Microscale Meteorological Models: Best_Practice_Guideline_for_the_CFD_Simulation_of_Flows_in_the_Urban_Environment
Do you need help with an upcoming project? Don’t hesitate to contact our dedicated Global Wind Engineering team, who will gladly assist. With offices in Sydney & Melbourne, Australia, London, UK, and Mumbai, India. New York & Miami, USA, Dubai, Hong Kong & Singapore, we guarantee to support you wherever you are based.
Building design and construction is a complicated process that includes a variety of variables and elements that must be taken into account to ensure performance, comfort and safety. The evaluation of wind loads on buildings and structures, which can significantly affect their stability, performance and overall efficiency, is one of the most crucial steps. They give engineers and designers the knowledge they need to make accurate and informed assumptions when progressing from design concept to detailed design of the building from landscape design to the design of the façade and structure.
Physically replicating wind actions on buildings and other structures is done in wind tunnel testing. A wind flow structure is set up in the wind tunnel that simulates the behaviour of the real wind at the same scale as that of the model. Wind Engineers can utilise this information to accurately observe how the structure responds to the wind loads. The capacity to quantify physical forces and deformations directly, as well as the ability to see and examine the wind flows around the structure, are all benefits of wind tunnel testing.
On the other hand, CFD testing is a numerical way of simulating wind loads on structures and buildings. This kind of testing is frequently carried out with the aid of computer software, which computes the wind flow around the subject building using mathematical models. When assessing the combined effect of wind and thermal effects, snow or rain, which are challenging to model using wind tunnel testing, CFD testing offers a highly detailed, three-dimensional representation of the combined effect of these various elements. However not all CFD modelling is the same and the more accurate modelling required complex turbulence models, a fine computation mesh and time steps, all of which require significant time and computational resources. Windtech is able to overcome the limitations of computation time by using a very significant size computation cluster. Windtech has been able to demonstrate that with such care and fine resolution, it is possible to model the flow around buildings to match those from wind tunnel results. However, there are still limitations in the accuracy of CFD when it comes to assessing the dynamic wind actions on façade and structures, particularly when the subject building is located within the vicinity of other buildings.
Hence the two techniques are complementary and each has its role in informing the design team in relation to the effect of wind on occupant comfort as well its effect on the structure and façade.
Our team of professionals at Windtech Consultants have contributed substantially to the standards that govern the practice of wind engineering and include world leaders in both wind tunnel testing methodologies and CFD. We can assist in recommending to you the best options to match your requirements and what is most appropriate for your project.
Need help with an upcoming project? Don’t hesitate to contact our dedicated Global Wind Engineering team, who will gladly assist. With offices in Sydney & Melbourne, Australia, London, UK, and Mumbai, India. New York & Miami, USA, Dubai, Hong Kong & Singapore, we guarantee to support you wherever you are based.
Windtech Consultants are pleased to announce the successful reconfiguration of its third wind tunnel test section to be blockage tolerant. Various codes of practice recommend limiting the blockage in the wind tunnel due to the effect of the model to within 8% or 10% to avoid distortion of the flow around the study building and the effect this would have on the wind effects being investigated.
Windtech’s third wind tunnel is now able to generate higher speeds at the test section without impacting the scale of models that can be tested. Validation tests were undertaken to compare against observed full scale measurements of the facade cladding pressures from the Texas Tech Experimental Building.
The first step in the validation involved testing a number of model scales of the Texas Tech Building, generating blockage ratios from 1% to 8%. The results show very good agreement against the full scale data for all these scales. This step is important to establish that all these scales of the boundary layer wind profiles in the wind tunnel are accurate and do not contribute to any deviation.
The second phase of the validation was to extend the shape of the scale models along a particular axis to generate blockage ratios of 5%, 13%, 17% and 21%. The results show that the blockage tolerant wind tunnel configuration is able to maintain consistent results (within 10%) with a blockage of up to 13% in the case of cladding pressures and up to 21% in the case of overall drag loads.
Windtech Consultants owns three state of the art wind tunnel facilities and has access to a fourth wind tunnel. This allows us to provide our clients with a high quality and timely service.
For more information or discuss the requirements of your current project, please reach out to our regional office via our Contact Us page. To get regular updates on news and events, please follow us on our LinkedIn page.
The emphasis has grown on ensuring safe and comfortable wind conditions in Leeds, due to the unfortunate death of an individual in 2011 when strong winds toppled a lorry near Bridgewater Place. While this may not relate directly to wind comfort or safety due to an individual’s direct exposure to wind, it highlights that the built form and urban landscape can cause adverse accelerated winds that are in some circumstances strong enough to move heavy objects. The latest guidelines introduced in July 2021, are the most stringent in the UK and possibly the world, with all buildings in the City over 15m requiring quantitative analysis. This means a study using Computational Fluid Dynamics (CFD) or Wind Tunnel Testing is required.
Figure 1. Render of Wind Flow Streams Around Building Generated by the CFD Analysis
Windtech Consultants are the key consultant providing detailed wind microclimate assessments for the Lisbon Street masterplan in Leeds. This £300 million mixed-used scheme sits on the former international swimming pool site and gained full planning in 2021. The project is developed by Marrico Asset Management and Helios Real Estate, the design is by DLA Architecture and Curtins are onboard as the Structural Consultant. There are four high-rise buildings which will include 600 build-to-rent flats in 33 and 22-storey towers, student accommodation in a 24-story tower and further space for hotels and offices.
Windtech has assisted during the design and planning application phase of the project. Given its height and scale, the Leeds Guidelines require wind engineering in the form of both CFD and wind tunnel testing for Pedestrian Wind Microclimate comfort and safety. Windtech Consultants, with world-leading expertise in both of these fields has undertaken both CFD and Wind tunnel testing on the project.
Figure 2. Artistic Render of Lisbon Street, Leeds (image courtesy of DLA Architecture)
Aaron Lefcovitch who is a Director with Windtech Consultants indicated that “we have tested the buildings in line with the City requirements and identified the areas where winds exceed recommended comfort and safety levels. This is the first step of the wind engineering process. Then we use what we have learned from more than 3,000 past projects to provide strategies that we feel will bring the wind conditions down to acceptable levels. It is not always required, albeit recommended to verify quantitatively the impact that treatment strategies have on wind comfort and safety, and we can do this by conducting further testing with treatments in place. Treatment testing can be an iterative process, however Windtech has the unique ability to home in on the most effective mitigation strategy very quickly without dragging out the project timeline unnecessarily. Treatments generally included strategic planting of trees and shrubs and strategic placement of screens, canopies and balustrades at various locations around the development.”
Figure 3. Image of Development Being Tested in the Wind Tunnel
Through this project and many others in the city of Leeds, Windtech now has a great deal of experience working with the Leeds local authority as well as providing a comfortable and safe environment for pedestrians within and around large developments in the City of Leeds.
We would like to congratulate Lisbon Street Developments, a joint venture partnership between Marrico Asset Management and Helios Real Estate, DLA Architecture, Re-form Landscape Architecture, Quod, CSD, Curtins, RBA, Turley, Brooks Ecological, Stroma Building Control, Jensen Hughes, Hydrock, Apex Acoustics and AA Projects for the rollout of this iconic development in Leeds.
If you are working on any projects that could benefit from the capabilities presented in this article, please reach out to our regional office via our Contact Us page.
To get regular updates on news and events, please follow us on our LinkedIn page.
