Simple as they may seem, louvers are a critical architectural feature that help maintain adequate ventilation and natural lighting in buildings. Placed optimally, they keep a building’s energy consumption low while raising the comfort of its inhabitants. This is good news for building managers and city planners, but deciding on the number and locations of louvers to maximize their positive outcomes remains tricky.
Computational fluid dynamics simulations, which model the flow of air or liquids under specific conditions, allow planners to assess a building’s ventilation and lighting properties before construction begins. “However, full explicit representation of louvers on buildings in urban simulations is computationally expensive, so louvers are often omitted in these simulations,” said Chinchun Ooi at A*STAR’s Institute of High Performance Computing (IHPC).
Full explicit representation means that louvers are modeled as smooth, flat structures with uniform thickness. Such details raise the overall complexity of computational fluid dynamics simulations. Ooi and his colleagues thus devised what they call a “porous media model” that is less computationally intensive. They then simulated wind velocity and pressure drop of air passing through porous media, comparing the results with that of the explicit representation model across a range of parameters, including the angle of tilt, blade length, and distance between blades of the louvers.
Compared to the explicit representation model, the porous media model required one magnitude less of computational power to complete. The researchers also showed that the porous media model performed similarly to the exact representation model for simple building simulations. Under more complex scenarios, however, the porous media model became inaccurate.
“Going forward, we plan to improve the accuracy of the porous media model for when the incoming wind direction is oblique to the actual louvers. We will also aim for an improved description of the impact of turbulence on the porous media model,” said Ooi.
The team is confident that their findings will help bring about awareness of the tradeoffs between accuracy and computational costs, enabling informed decision-making by industry practitioners.
“This is a first attempt to quantify the loss in accuracy from using the porous media model relative to a fully explicit simulation. Hopefully, our findings will increase the receptiveness towards including louvers in building simulations for design and optimization, as opposed to completely omitting louvers from the models,” he concluded.
The A*STAR-affiliated researchers contributing to this research are from the Institute of High Performance Computing (IHPC).