BIM and sustainability: a growing partnership


October 2014, By Simon Gillis, Technical Manager, Autodesk.

According to a recent manifesto from the New Sustainable Energy Association, the UK could save £12.2bn a year between now and 2050 if it focuses on delivering greener buildings. Traditionally, it's the environmental factor which has driven sustainable building, but now businesses are also recognising the financial benefits.

An example of this is the Government's initial 2016 zero-carbon mandate for all new homes, which was focused on promoting green policies and sustainability. However, there is now also political recognition and backing for the business and economic value of sustainable buildings, with the same zero-carbon standard being applied to all non-domestic structures by 2019.

To achieve the initial 2016 mandate, the government also simultaneously created the BIM Task Group. It recognised that by using BIM technology it could help reduce investment costs and the impact on the environment by up to 20% by evaluating considerations such as building materials, air leakage, build costs and householder experience. We're still at the stage where the construction industry is working out exactly how BIM can be used to design and create structures that are sustainable in every sense of the word, but there's already been a great deal of progress in this area.

At the core of sustainable building is design, and it's important for designers to ramp up their knowledge of sustainable practices. In the 1980s there wasn't so much consideration about sustainability or cost of use - we built big shiny glass towers and fitted expensive and inefficient air-conditioning systems as an afterthought to make them habitable. But now, as the clean tech market matures, technology has developed and BIM makes it much easier to design sustainably, without comprising on aesthetics.

Some industry practitioners have embraced BIM as a logical next-step process in aiding sustainable design and construction of eco-friendly buildings. However, although BIM has gained traction in recent years, its pairing with sustainability is still only an emerging trend, and there remains confusion with architects and engineers as to the benefits it can deliver. But there are many reasons why BIM should be an essential tool in sustainable design. Its fundamental processes - simulation and visualisation - enable professionals to become more efficient and make more informed decisions. It also enhances cost-effectiveness by, for example, reducing wastage of time and materials.

More and more building projects are putting sustainability at the forefront of design and using BIM tools, such as energy simulation, in the construction process. At a basic level, BIM incorporates visualisation software so that architects are able to create photorealistic renderings that outline the physical, real-world space available. This enables them to efficiently design the building and include space-saving concepts such as mobile working areas, desk sharing features and telecommuting, which not only reduce the size of the area built but also achieve a corresponding decrease in energy usage.

Visualisation can also be used to test out various sustainable methods prior to constructing the building, by incorporating details of the surrounding areas into 3D BIM software. For example, New York-based architects SHoP were able to make changes at various stages of the design process of the Botswana Innovation Hub because they used a model-based design prior to construction. This meant that following a series of reviews by a number of architects and structural engineers, they came up with the best sustainable practices for the building, which included changing the parking structure to reduce the amount of steel needed - reducing the structural costs by up to five per cent. They also analysed the impact of sun on the building, implementing ample overhangs to shade and keep the building cool and formed a living roof, which collects rain water for reuse.

he process is not limited to new builds; it can also be applied to existing structures to improve sustainability. In a retrofit, the building is captured with a camera, satellite images or a laser scan, and architects run energy simulations that detail how the building could optimise its energy usage. A simple retrofit example is installing a 'cool roof' to reduce cooling loads during the hot weather, which can be achieved by either analysing the roof type or considering placements of rooftop photovoltaics (PV). The design software has isolation values embedded that can identify where the sun and its shadows are at every hour of every day of the year predict whether cool rooftops or PV panels offer better cost savings.

As BIM can be easily scaled up, it can also be used in large projects, such as assessing and designing entire cities. For example, Vancouver built a simulated version of its entire city by combining terrain files, building footprints, satellite photos and GIS data into a 3D modelling program. With this information it can identify how shifts in population affect density and how the landscape would change due to new infrastructure projects, identifying if there are any opportunities for a mass building energy retrofit to improve sustainability.

These are just a few ways that BIM can be used in designing and constructing sustainable buildings, but they aptly highlight beneficial ways in which the process is enabling the architectural, engineering and construction industry to design eco-friendly and sustainable buildings, mapping the way for the cities of the future. Using such digital tools allows for construction to be simulated before a structure is built or adapted, permitting observation, analysis and discussions that lead to the best economic and sustainable decisions possible for the project. And now that BIM can be used in the cloud, it's so much easier for architects, engineers and contractors to collaborate, which reduces errors and increases efficiency.

To reach the economic savings mapped out by the New Sustainable Energy Association, planning for the future is essential and BIM enables professionals to be innovative while mitigating the risks of trying something new and unpredictable. As these sustainable building practices become more mainstream, more data will be collected which will make it easier to incorporate best practices and key principles into structures of the future. This is important not just in terms of the initial design and build costs but, more importantly, the running costs and return on investment on the build, as owners look for the most energy efficient solutions.

As seen by the various initiatives undertaken by the government, not only through the zero carbon mandates but also planning policy statements, sustainable will become the norm. Designing for green should no longer be an afterthought; it's time to embrace it at the start of the process. Depending on the build, whether a new design or retrofit, the sustainable attributes will be varied but the overall benefits of BIM will remain the same. Ultimately, BIM allows for a more informed approach to design and construction, ensuring that projects are completed on time and on budget, and utilise the best sustainable practices available to them.