SUSTAINABLE design has gained an increasing prominence in the construction industry at about the same time as building information modelling (BIM) has emerged as a new mechanism of project delivery.

Industry innovators are now seeking to unite these two areas to meet common objectives of integrated project processes, efficient construction practices, and sustainable outcomes.

This is the realm of Green BIM.

In the last few years, there has been increasing awareness in the Middle East of the need to move towards green buildings, with GCC governments promoting the adoption of international sustainability standards and in some cases forming new legislation. In 2008, Dubai enacted a green buildings directive to encourage the adoption of international green building specifications. In September 2010, Abu Dhabi brought into effect the first requirements for its Estidama Pearl Rating System.

The shift in policy has been reinforced by major initiatives that have established benchmarks for sustainability in the region. In Saudi Arabia, the King Abdullah University of Science and Technology (Kaust) showcases the world’s largest Leed (Leadership in Energy and Environmental Design) Platinum building. The UAE too received world-wide attention when it unveiled plans for the development of the world’s first carbon-neutral city, Masdar, in Abu Dhabi.

Building on this regional momentum, there is an opportunity for significant developments in sustainability and perhaps a more decisive shift towards Green BIM.

A case for Green BIM
Green building project teams are increasingly discovering how BIM tools can help them achieve more sustainable outcomes, while providing an immediate insight into how design decisions impact building performance. BIM also encourages an integrated design process – a critical strategy for making projects greener.

1 Bligh Street ... six-star Green Star Office Design V2 certified rating.

The underlying premise of BIM is that the information model remains the authoritative source of project data, with all project members having access to this information (drawing from, and contributing to) to perform their specific duties. Thus, for example, when an energy consultant performs an analysis, he can be confident that his assessment is based on the most current information available. Furthermore, the data from the analysis is fed back into the BIM, contributing to the richness of the model and becoming available to all other project parties.

The advantages of this methodology in sustainable design are huge as green building analysis relies on accuracy and immediacy of information. In the BIM environment, the sustainable designer has the ability to access the complete project data to undertake comprehensive analyses and make informed decisions. Furthermore, these “Green BIM activities” are not restricted to the design phase, but can be advanced during construction and operation of the facility.

Green BIM operation
Design: Building performance analysis is the most common form of Green BIM operation. It refers to a broad range of activities that measure the design of the facility against performance-based criteria. Typical performance analyses include modelling heat loadings, energy consumption, lighting analysis, shading and glare studies, acoustic analysis, optimising HVAC (heating, ventilation and air-conditioning) design and modelling computational fluid dynamics (the simulation of dynamics such as air movement).

Simultaneous multi-disciplinary assessments are a more complex set of operations that can assess how changes in one discipline affect the performance of other interrelated disciplines.

Construction: Green BIM can also relate to various functions within the construction phase of the project. These may include developing efficient construction methods, controlling site logistics, monitoring material selection (such as recycle content) and minimising waste.

Operation: In the operations phase of the facility, the BIM can be progressed as a lifecycle tool. In this application, it is possible to capitalise on the latent data of the BIM to monitor building performance and verify against established design criteria. The BIM can also be used to predict how the building would perform under changed conditions, such as future alterations or to simulate disaster scenarios.

Integrating Green BIM
Let’s examine some of the drivers and obstacles facing the industry in the deployment of BIM in sustainable projects. In a new field such as Green BIM, the associated technologies and processes are in constant development and transformation. Some practitioners struggle to grasp the underlying concepts of BIM and sustainability, let alone wield the complex tools and integrate them with their existing practices.

A recent survey report by McGraw Hill Construction entitled GreenBIM: How Building Information Modelling is Contributing to Green Design and Construction (published in the US in 2010) notes that only 17 per cent of Green BIM practitioners are realising more than 50 per cent of BIM’s potential to help achieve their green objectives. However there is strong recognition of the value of Green BIM and a tremendous desire for practitioners to increase their operation. The report further cites that 78 per cent of BIM users currently not using BIM on green projects expect to be doing so within three years.

According to the McGraw Hill Construction report, the key factors that would influence a ‘non-Green BIM’ company to start using BIM on green projects are owner demand (85 per cent) and saving time and money (76 per cent). Owners, in turn, say that the key drivers for them to adopt BIM would be legislative requirements and better return on investment (RoI).

Current trends suggest that there will be an increasing impetus to adopt Green BIM practices as regional governments push the green agenda, and forward-thinking organisations seek to differentiate themselves with ‘green credentials’. RoI can also be a realistic outcome.

In the best-case scenario, owners can realise RoI through the adoption of leaner construction methods and overall increased productivity; however, the greatest benefit will be found in the operation of the facilities.

Among the perceived barriers to the integration of Green BIM are the resistance to adopt new technologies and processes, and potential difficulties encountered with buy-in from all project stakeholders. Even in cases where the ‘green’ agenda is client-led, there can be resistance from downstream project members. Owners have cited difficulties ranging from delays in the provision of material specification (as green certification typically requires a higher level of documentation) to interoperability issues between the software deployed by different parties.

According to the McGraw Hill Construction report, the greatest factors deterring ‘non-Green BIM’ users from using BIM on green projects was the perception that it was easier to do green projects using existing tools (47 per cent of architectural and engineering – AE – firms) and that the BIM tools did not have the required functionality (34 per cent of AE firms). This sentiment springs both from a resistance to adopt new and complex technologies, which require a transformation of existing practices and general upskilling, and an apparent lack in confidence in the available tools.
Another area of complexity in Green BIM application is the integration of BIM processes with green building certification systems. Most rating systems, although supportive of analysis tools, do not have a process for BIM integration. However, this is something that is likely to change in the coming years.

Green building certification
In the UAE, Abu Dhabi’s Pearl Rating System is seeking to streamline the sustainability process, with links to the Estidama Integrative Design Process (EIDP), which encourages design coordination at the early stages of the project.
The United States Green Building Council (USGBC) has for some time been developing the integration of BIM with the Leed rating system. The Leed Reference Guide for Green Building Design & Construction 2009 Edition identifies specific credit points that can be more readily assessed with specific building performance analysis software. The integration of Green BIM will be further progressed with plans to update LeedOnline software to allow BIM to feed project data directly into the USGBC database. This development recognises the huge amount of latent information held within the BIM. It facilitates the logical progression of the BIM from the original source of design data to the final mechanism of verification.

Best practices
In order to maximise the usage of BIM in green projects, one can develop a Green BIM project execution plan. This is a detailed strategy to determine what are the agreed-upon ‘green objectives’, and how the BIM will be deployed to achieve these.

The execution plan may include an overview map that sequences the desired functions and assigns responsible parties to the various activities. This is an excellent means to track the BIM progression; identifying what data is required in the BIM, and what are the desired outputs at the progressive stages of its development. It may also be necessary to ensure that all project participants have integrated processes, with agreed-upon delivery methods, file formats and interoperable software.

Case study
The following case study looks at how the BIM execution strategy helped achieve a world-class sustainability outcome in a complex project in Australia.

1 Bligh Street, recently completed in the heart of Sydney’s central business district, has been awarded a six-star Green Star Office Design V2 certified rating for environmentally sustainable design (ESD). This is the highest possible rating – roughly equivalent to Leed Platinum and considered ‘world leader’ performance – and sets a new standard for high-rise office buildings in Australia. The building is notable, not just for its green credentials, but also for the integration of BIM throughout the design and construction process.

Commencing at early concept stage, BIM was deployed for design and engineering analysis, culminating in the integration of 35 distinct trade models during construction, and is planned to continue as a federated as-built model for future use in facilities management.

At an early stage, it was determined that a single centralised BIM would not be a feasible strategy, and it was decided for the initial phase that distinct models for each primary discipline (architecture, structure andmechanical, electrical and plumbing – MEP) would be developed and referenced into one another. Each model was thereby independent, acting as a host for the other linked models. This resolved a number of issues regarding ownership, authorship and responsibility, as well as the practical difficulties related to the physical location of the model files, and the need for a number of team members to work simultaneously on the files.

At the time of the appointment of Grocon as main contractor, the client set a strong mandate for the entire project to be produced ‘in BIM’. Accordingly, all subcontractors were required to provide BIM data, and Architectus of Australia, architect on the project, was appointed as BIM manager to develop standards and protocols, institute training regimes, aggregate models and produce and manage coordination models. The standards included a detailed, discipline-based list of required object parameters to provide a consistent level of information for all object types. This was no easy task, as the BIM reached a new level of complexity.

Architectus established a model issue cycle for use by the consultant and subcontractor team. Coordination reviews occurred in regular meetings with discussion around a live model. Decisions were taken and action items were generated which were incorporated into the models in the next cycle.

Following the completion of construction, an ‘as built’ model is being created by the merging of the architectural model and the linked models. The model can be exported in formats to suit the requirements of end-user applications. Typically, this would be native or IFC format where there is a requirement for further BIM functionality.

Architectus concluded the high ESD objectives of the project demanded extensive building performance analysis, dependant on accurate and up-to-date information from all disciplines. Such operations could hardly be managed in a non-BIM environment.