BIM & LCA – aiding a more collaborative approach to sustainable design.

In 2019, the International Organisation for Standardisation (ISO) published the first two international standards for Building Information Modelling (BIM):

  • BS EN ISO 19650–1 Organisation of information about construction works – Information management using building information modelling – Part 1: concepts and principles
  • BS EN ISO 19650-2 Organisation of information about construction works – Information management using building information modelling – Part 2: Delivery phase of assets.

Both of the ISO 19650 standards supersede BS1192:2007 + A2:2016 (principles) and PAS1192 part 2 (capital/delivery phase).

This long awaited move to an international BIM standard not only allows for greater collaboration on global projects, but also brings designers and contractors closer together through clear and precise information management.

So where does LCA fit into this?

The earlier you engage with Life Cycle Design the better. It is at pre-design stage where any decisions made have the biggest influence on energy demand and the environmental impact of a project, while featuring the smallest costs for changes to the design.

It is at early design stage where we need to come together and adopt a collaborative approach on a design that maximises its sustainable potential by including all parties in the design process.

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As we have established, efficiency and collaboration on a project is the key factor during early planning stages. When it comes to sustainable buildings, designers will need to be aware of a plethora of information such as embodied carbon, resource use and toxicity. It is highly likely that this will require numerous iterations of the design, in order to produce the desired outcome.

The use of BIM in the design process will allow the design team more time to consider the sustainability factors of the project, by engaging with other members in a more collaborative approach.

With the advancement in BIM/LCA technologies, we are now in a fortunate position where there are LCA tools that can be integrated with BIM to assess the environmental impact of a building.

Standalone embodied assessment tools require data or a model to be imported from a separate BIM modelling application each time an assessment is carried out. Aside from being a laborious task, this is highly inefficient, and collaboration between all parties breaks down.

Many LCA tools have now been developed that offer BIM integration, however there still needs further improvement until LCA can work seamlessly within BIM. In many cases the result are far from ideal, with workflows being unable to work correctly in real life projects.  One contributing factor that can cause inaccuracies and mistakes in LCA results when produced through a BIM integrated workflow, is the human factor.

This is predominantly due to the level of detail in the BIM model. The LCA results will only be as correct and accurate as the BIM model itself. Omission of an element in the BIM model will naturally lead to the respective LCA scope reduction. Incorrect or too generic modelling of an element in the BIM model will lead to false modelling of this element in the LCA model.

Although the above principle can apply in all AEC BIM workflows, in the case of LCA, the effectiveness of the workflow also highly depends on the basis over which the LCA tool works. There are two distinct methods to obtain the Quantities Take-Off from a BIM model, the component level method and the material level method. When the material level method is used, the quantities are extracted from the BIM application material by material, sometimes with meta data showing the component this material belongs too. When adopting this approach, the Human Factor can negatively impact the accuracy of the results quite significantly. This is due to the current Level of Detail (LOD) the industry usually applies in the BIM models. A typical example of this are the glazing quantities, since it is very unlikely and probably also not worthwhile for the modeller to model the exact thickness of the two glazing panes of double-glazed window. Instead it will be modelled as one thick layer of glass that also overlaps the air gap between the panes. In addition, in the early stages most of the elements in a BIM model are filled with generic materials that describe the element itself instead of the actual material.

Using the component level method, which is also the approach followed in eToolLCD, the quantities go along with the components, not the materials. This means that the user will get the total area of a double-glazed window, not the total volume of glass and the total volume of the frame. This gives the user the opportunity to map these components with the respective ones within the LCA tool.

In eToolLCD, this approach is enabled by the utilisation of an extensive component (or template as it is known within e ToolLCD) library, which are essentially the virtual twins of the BIM components and the real life constructed components. With minimal effort from the LCA practitioner, they can then map all material quantities with LCI data sets, enabling higher accuracy of the final results due to the way the low LOD is handled and resolved.

By opting for whole of project life cycle assessment tools (such as eToolLCD) that are incorporated within widely used BIM applications i.e Revit, via a plugin (see this post for further information on eTool’s Revit plugin), it will encourage a more collaborative approach, enabling all parties involved in the project to have an input and make it possible to assess the overall sustainability of a project from conception through to demolition.

With the new ISO BIM standards focusing on collaboration, coupled with the LCA/BIM holistic approach to sustainable design, this truly gives us the opportunity to have a positive impact on our surroundings and the environmental impact of our buildings in the future.

Related article: Does eToolLCD integrate with 3D CAD packages or BIM?

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