Smart Windcatcher: A CIBSE Winning Concept

As part of the CIBSE Inter-University Student Design Competition 2022, a group of nine Heriot-Watt University Dubai Architectural Engineering students won 1st Place at the annual CIBSE UAE Awards. Team Barjeel proposed a design of a Smart Windcatcher based on a combination of passive and active strategies that can provide outdoor thermal comfort through renewable energy sources.

Three B.Eng. Architectural Engineering graduates from the Class of 2022, Priyanka Murugappan, Sana Hafsa, and Vinuki Arachchi, elaborate on the winning proposal and their own views of the project.

The Project and Aim

The main aim of the proposal was to enhance the surrounding microclimate and reduce the energy consumption of buildings surrounding the windcatcher. Team Barjeel took UAE’s growing affinity for outdoor activities, including the huge success of the EXPO, into consideration. Although the EXPO received a lot of visitors, the hot and humid climate directed the peak visiting hours towards the evenings. Using this scenario, the team focused on designing a smart windcatcher that can be installed outdoors, combining both passive and active strategies to achieve thermal comfort while being independent of the grid. Windcatchers have traditionally been used as an indoor passive cooling strategy, and how this practice can be turned into a smart system to cool outdoor environments was Team Barjeel’s main focus. We were also able to utilize our experience from the Solar Decathlon project, which incorporated a 3D-printed concrete windcatcher as a case study to build our idea up.

Features and Operation

The Smart Windcatcher is derived from the Monodraught ‘Windcatcher Zero’ currently in the market. Our modified product contains additional features such as solar-powered motorized fans, dampers, and temperature and CO2 sensors to achieve a net-zero product overall. It is designed to be self-sufficient in its operation as the motorized fans and sensors are interlinked within a remote BMS system and powered by four 15W monocrystalline PV panels. This not only eliminates dependence on the grid but offsets its embodied carbon emissions of 500 kg CO2 within a short duration of time. Ultimately, the design can contribute to achieving up to 5 credits under the LEED v4 standard and up to 3 optimizations under the WELL Rating System.

The windcatcher’s dimensions and features were developed based on multiple trials and best-performing conditions as per the ANSYS Fluent CFD simulations. It contains air intake louvers at the top and air outlet grilles at the bottom, as depicted in the figure below. The fresh air flows in through the louvers and cools down as it travels down the chimney and eventually out through the grilles at the bottom. 

The windcatcher operates and switches between two energy-efficient modes: natural and mechanical ventilation. It does this by communicating with the built-in temperature sensors in order to provide cooling even during periods of low wind speeds. The natural ventilation mode works by taking in the prevailing wind, while the mechanical ventilation mode is operated by solar-powered motorized fans. Remote data monitoring combined with the sensors allows the windcatcher to perform at its optimum efficiency.

User Expereience Scenarios

User journeys portray an important role when the factor of convincing an audience of your idea comes into play. This can typically be for monetary incentives, although in this case it was to win the competition successfully. Without clear communication, an idea often remains as just an idea because your audience is unable to understand either how it works or why it is needed. User journeys allow the audience to understand how the technology actually impacts the end user by explaining scenarios that different types of users interacting with it would experience, such as the Maintenance Team, Facilities Managers, Visitor Experience Team or the typical Visitor.

For example, with a smart windcatcher, due to the monitoring and data analytics through the computer system, facilities management can be notified of the exact time a filter may need to be replaced. This would ensure the air quality is always up to the standard. With a passive windcatcher, this may have only been noticed during a periodic check-up or even a complaint from a visitor. Visitors, on the other hand, may not experience optimal thermal comfort with a passive windcatcher and hence fewer visitors and low site profitability. The smart windcatcher can draw large crowds even during the summer and achieve a higher payoff.

Dynamic Simulations

The IES-VE (Integrated Environmental Solutions – Virtual Environment) simulations were undertaken based on the natural ventilation mode on the windcatcher to assess the microclimate in the warmest time of the year. The simulation results were purely based on wind pressure buoyancy forces. In the MacroFlo analysis, internal air temperatures and velocity were analyzed. The results of the Venturi effect in the windcatcher that drives the air in and downwards due to the air pressure difference validated the idea that the air temperature decreases as air flows downwards. The velocity contours depicted higher volumes of air with faster velocities being distributed to the surrounding environment.

The IES-VE MicroFlo computational fluid dynamics (CFD) analysis was used to analyze external air parameters around the smart windcatcher at a micro level. It demonstrated that the external airflow velocity reaches its maximum at the top of the windcatcher leading to a highly efficient system. Pressure contours also showed that the windcatcher expands the majority of the incoming air, decreasing the concentration of CO2 as the air travels down and out through the grilles.

ANSYS Fluent CFD analysis was run in addition to the IES-VE simulations to showcase a 7°C drop in air temperature from the top to the bottom of the windcatcher at peak outdoor temperatures. Additionally, due to the motorized fans, the wind velocity can increase by up to 4 times, thus providing coolth to the surroundings. Heat lost by the surroundings from just one windcatcher was estimated to be approximately 11.2 kW.

Personal Experiences

Priyanka Murugappan: It has been a privilege to lead and work closely with Team Barjeel to design an innovative technology for the competition. Knowing that the Middle East is quite famous for hosting outdoor activities eg, EXPO 2020, Global Village, etc, we considered the issues faced by users at such events and came up with the idea of reengineering a traditional windcatcher that uses both active and passive measures to cool the surrounding environment. We are grateful to CIBSE UAE for supporting and recognizing our efforts.

Sana Hafsa: The aspect I worked on for our smart windcatcher proposal was the user journeys. This was to support the technical aspect of the idea by communicating its benefits, made clear by comparing the features of the smart windcatcher with a typical passive windcatcher. This experience was a wonderful way to wrap up my university years as I was able to apply all the technical and soft skills I learned in university through my internships, as well as through live project experiences. These kinds of competitions are one of the best ways for students to learn as it challenges them actually to apply their knowledge in unique ways. It is also a wonderful way while studying to engage with the industry and gain connections that can be useful after graduation.

Vinuki Arachchi: I contributed to analyzing the surrounding microclimate and assessing the internal temperatures and velocities using IES-VE.  Both the internal and external simulations proved to be valuable tools in providing proof that the smart windcatcher can run as proposed and provide a thermally comfortable microclimate. It clearly showcased how the windcatcher would work in UAE’s climatic conditions and predict the possible performance outcomes and issues that the real-world product might undergo. Working on this project further enhanced my dynamic modeling skills, and the knowledge helped me in my career after graduation. It was an honor to see our proposal being applauded by multiple sustainability consultants and energy experts in the industry for its innovative methodologies.

At Alpin, we are committed to ongoing research into every aspect of sustainable and environmental design for spaces, buildings, communities, and cities. By forging relationships with academic and industry experts, we can ensure that research continues to keep this vital field of work alive. Alpin is proudly partnered with Heriot-Watt university and envisions providing innovative practices that promote efficient, cost-effective, and industry-changing delivery of projects‘ success targets in terms of design, construction, and operations. 

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