By Shonn Mills, Global Director High Rise, Ramboll.
As the height of a building increases, so do the engineering demands on its systems. The result is that the embodied and operating energy of the building is higher than traditional low-rise construction.
An important consideration when examining this question is evaluating high rise in the context of urban density. A new study by Dr. Anthony Wood, Executive Director of the Council for Tall Buildings and Urban Habitat (CTBUH) ”Dense Downtown vs. Suburban Dispersed: A Pilot Study on Urban Sustainability” considers not only the buildings as standalone elements but includes other factors such as infrastructure requirements (roads, utilities) and the energy impact of transport.
Among other things, the study shows that low-rise suburban development can require up to 5-10 times the road and energy infrastructure as high rise. Thus, while tall buildings as a stand-alone solution have an inherently higher embodied energy, high rise can be part of an overall more sustainable solution when considered in a wider context.
This is why independent experts argue that it can often be easier to optimize sustainability in a smaller area than if building an urban sprawl – as transport problems and their associated health and economic effects are avoided. According to Deo Prasad, Director of the Centre for Sustainable Built Environments, urban sprawl is “a far worse option than high rises.”
However, as an industry we must also challenge ourselves to make stand-alone high rise more sustainable and part of the solution to the resource and climate crisis
One of the most efficient methods is using prefabricated components manufactured in a controlled, offsite environment. This is cheaper because it significantly decreases construction times by enabling construction and engineering challenges to be addressed before construction starts. It also reduces the number of workers as fewer activities are carried out onsite - which in turn reduces noise and minimizes the impact of construction on the local area, including lower air pollution and CO2 emissions.
Offsite construction can also be used on high rise; Ramboll used this technique on two significant projects - one of the world’s most leaning precast buildings, the award-winning Hotel Bella Sky in Copenhagen and Travelodge, 250 City Road in London.
The use of offsite construction is evolving beyond assembling small 2D elements. We are now prefabricating full 3D modular building components from bathroom pods to full hotel rooms or apartments. We are currently trying to challenge the upper limits for modular high rise, and we are developing prototypes for full 3D modular high rise.
Improving Energy Efficiency
Another way to make tall buildings more sustainable over their full life cycle is to improve their energy efficiency. Energy efficient high rise is achieved by minimizing the energy demand requirements through solutions like double skin facades which improve insulation and minimize solar gain while still maximizing natural light.
Energy efficiency is not only limited to minimizing the demand but also exploring solutions which incorporate on-site energy generation into the building design.
A good example is Bahrain World Trade Centre where we have incorporated wind turbines on one of the most iconic towers in the Middle East.
An emerging powerful tool for innovative new ways to create sustainable solutions on high rise is integration with the digital environment.
Tall buildings can be designed as platforms to take full advantage of the latest and future SMART technology. Thousands of SMART sensors feed data to the integrated Building Management Systems to allow the building to adapt and optimize for improved energy efficiency, safety and security.
Furthermore, SMART technology integrated with the architecture can provide improved comfort and productivity for the building users and create new experiences and opportunities for collaboration.
Real sustainability is more than just the implementation of energy efficient and renewable technologies to enhance the ‘green’ credentials of the building. It is also about delivering a livable environment to maximize the health, wellbeing and comfort for occupants.
Making use of these strategies in an integrated way creates value for both our clients and for society as a whole – and provides a blueprint for sustainable high rise.