“Urban heat island” (UHI), a phenomenon illustrating significantly warmer temperature in the built areas or city compared to its surrounding areas, can be tackled through several ways, one of which through “Cool” Building Envelopes – a concept that emits less heat.

The level of importance to tackle it is increasingly alarming, partially as urbanization rate continues to rise. Furthermore, urban heat island can potentially exacerbate some of the projected impacts of climate change, such as heat waves and hot dry season spells.

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In the typical infrared image of a city, temperature distribution is illustrated to identify a range of heat level radiated through different solar radiation absorption rates, operating devices and technologies, reflectiveness prevalence of building materials, etc.

In Singapore,  for instance, “hot spots” are normally observed in exposed hard surfaces such as industrial areas, airports and Central Business Districts; while the “cool” spots are mostly observed in large parks, landscapes in between housing estates and water catchment areas.

Cooler building envelopes

The building envelope is a part of a building that forms the primary thermal barrier between interior and exterior elements in determining levels of comfort, natural lighting and ventilations and how much energy is required to heat and cool a building.

In mitigating urban heat island, building envelope requires improvement towards a concept that radiates less heat – a Cool Building Envelope, that is.

In hot climates, low cost solutions such as reflective roofs and walls, exterior shades and low emissivity window coatings or films can curtail energy consumption for cooling.

Building surface’s temperatures can drop considerably if neighboring buildings are implementing bio-inspired retro-reflective façade, as it reduces the energy required for cooling.

Air sealing, restricting the passage of air through the building envelope are also keys in increasing energy efficiency – which eventually helps better manage heat transfer and mitigate urban heat island rate.

Making the UHI mitigation happen: government support & regulation

Policy makers must take responsibility for establishing goals for the energy efficiency of building envelopes, both to the extent of new buildings construction and building retrofits. Deployment of UHI mitigating technologies is advised to be facilitated through innovative financing mechanism.

Furthermore, building energy codes should also require, for example, roof attic insulation that meets the latest standards emitting minimum UHI.

In Singapore, the existing thermal regulations may actually help control the building’s energy consumption. And such regulation as well as incentives can actually drive demands towards energy efficient buildings and technologies, unlocking the full potential to generate a greener urban future, greater comfort and health for the inhabiting communities. (AGB.com – VL & SA)

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