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Pushing the envelope on green building roofing and Windows

Do Huu Nhat Quang, co-founder of national and Southeast Asian green building consultancy GreenViet argues energy savings are an obviously intrinsic part of green building ratings. Addressing building design from the outset can help in cutting energy-saving costs through better roof and wall insulation.


The shell or ‘envelope’ of a building can drastically affect energy efficiency

Energy efficiency is among the critical categories adopted by all rating tools including LEED, or Leadership in Energy & Environmental Design, a widely recognised green building certificate all over the world. In most rating tools, energy saving is a prerequisite for a green building. If a building fails on this, a building will fail to secure a certificate despite complying with other requirements. An energy-saving threshold of 10 per cent is normally a minimum requirement for a green building.

There are different strategies available to help save energy. Some popular strategies focus on using energy efficient equipment and architectural features, but the envelope would be the most important to consider before going further into other solutions. A typical envelope of an industrial building includes the metal roof and walls. A well-insulated envelope is obviously beneficial to energy saving.

Cool roof

A cool roof has two important characteristics: high solar reflectance and high thermal admittance. While high solar reflectance helps reflect sunlight and heat away from the building which reduces roof temperatures; the latter helps roofs absorb less heat and stay cooler than conventional roofs during peak summer weather.

A cool roof can be single or multi-layer. If single layer roof is used, then a high SRI- Solar Reflectance Index - should be selected. LEED nowadays promotes the use of roof materials with SRI above 78, which is supplied by a few demanding manufacturers. The lucky thing for the environment is that high SRI roof material is not more expensive compared to the same material type in some cases. This helps building owners and design professionals as they do not have to consider the extra investment while obtaining serial benefits.

The multi layer roof is more flexible in reinforcing the insulation. While the top layer cares about the SRI, other layers below can help reduce U-value, a measure of heat transmission into the building. Some popular multilayer solutions are double skin, sandwich panelling with PU inside or even just placing an insulation layer right below the top material. It totally depends on the specific requirements of a project to help select the appropriate roofing structure.

A cool roof provides more benefits beyond energy savings for building owners. It helps mitigate urban heat island effects, which helps reduce the temperatures in the communities where buildings are located. As for using less energy, cool roofs also help reduce air pollution and greenhouse gas emissions. Improved comfort for the occupants is a by-product of reduced internal temperatures whether air-conditioning is used or not.


Besides the roof, the walls play an important role in insulating the building, helping reduce cooling energy. The wall system may include brick, metal wall with insulation and glass for doors and windows. Alternatives to clay bricks include concrete blocks and AAC boosts insulation and helps protect the environment. Insulation layers like rockwool inside the wall can also help with better insulation.

Low e Glass

Using glass is always tricky for any design professionals. On one hand, glass helps gain day-lighting and views for occupants which is good. But on the other hand, glass allows heat to enter and adds to cooling costs. In addition to appropriate proportions of glass to wall, a good glass that allows the daylight in but keeps the heat out will help a lot in energy savings.

There are a variety of glasses available on the market nowadays but several typical types are popular or worth on cost-analysis in terms of Vietnam’s conditions and application in green buildings. Low e glass is among one of appropriate selection to allow light in, while mitigating the heat. This low e glass performs even better in insulation if it is assembled with another glass layer with argon or air in between to make a double glazing type with typical U-values from 1.8 to 2.


Vietnam Investment Review under the Ministry of Planning and Investment



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Add: 860/60s/16 Xo Viet Nghe Tinh Street, Ward 25, Binh Thanh Dist., HCMC

Tel: +84 28 3511 90 96

Nguyen Thi Huong Thu - Mobile: +84 985 277 099 - Email:

Do Huu Nhat Quang - Mobile: +84 903 613 816 - Email:


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