A solar study for an innovative building façade in a jurisdiction with strict regulations
DUO is a mixed-use development in Singapore’s Bugis district. The project includes two towers: one with 49 storeys of residential space, the other with 39 storeys of office and hotel capacity. Both towers are striking for their unusual curved shape and for their façades, which feature a honeycomb-like raised metal brise-soleil.
The design of DUO’s façade was driven not only by aesthetic concerns, but by a desire to limit solar heat gains inside the building. In addition to using high-tech glazing to help keep the sun’s energy out, the designers adopted the honeycomb façade partly to cast a pattern of cooling shadow over the building, like a net. Singapore has some of the strictest anti-glare regulations in the world. DUO’s designers had to gain a detailed understanding of reflection impacts from their façade. Specifically, they aimed to confirm that their innovative hexagonal shading devices were effectively limiting potential glare effects on drivers and pedestrians. Designers needed to be confident that the façade didn’t cause any unexpected reflection impacts that could prevent the project’s approval by local officials.
DUO’s developers engaged us to investigate the visual and thermal impacts of the project on nearby buildings, public spaces, and transportation routes – and also whatever impacts the two towers might have on each other.
We began with a screening analysis to understand how often various reflections occur and what their maximum intensity could be. Getting a broad overview of reflections at the site is a helpful first step because it lets us quickly determine areas where we need to perform more detailed analysis. For DUO, our screening analysis included all grade-level spaces within several hundred meters of the building, the on-site amenity spaces, and the facades of the two towers themselves. Our screening analysis revealed that none of the reflections the buildings would cause could be expected to reach maximum intensities sufficient to cause thermal damage. We also found the frequencies at which visual effects might occur was low.
Nevertheless, some areas warranted further investigation – and we worked with the building’s design team to identify receptor points for more detailed analysis. By taking a closer look at how reflections were affecting specific sites around the buildings, we were able to understand whether the effects were serious enough to cause a nuisance – either glare or unpleasant thermal conditions. Had we found problems that needed addressing, we could have worked backward from the receptor points of concern to identify which areas of the towers’ facades were causing the problem.
Our study was able to demonstrate to the designers – and ultimately to local building authorities – that DUO’s facades would not cause excessive visual glare or thermal damage. Indeed, the honeycomb shading apparatus designers had adopted to control solar gains inside the building also proved to be effective at limiting solar impacts (reflections) outside. The fact that the façade promoted comfortable conditions for building occupants as well as for neighbours helped to ensure that the shading devices survived the value engineering phase of design – and that local building authorities allowed development to proceed. Construction is scheduled for completion in 2018.