Extent of Modelling Refurbishment Works

  • Dear eTool,

    have a question in terms of what is (and is not) allowed for modelling existing and refurbishment works (as it relates to Green Star or any other international standard):

    The project consists of a new 60,000m2 GFA hospital but also includes approx 5000m2 refurbishment works (mostly internal but some infill slabs, new walls, linings and finishes, fittings and equipment) to an existing 90,000m2 hospital

    While LCAs always encourage reuse of existing buildings (which is also in turn a key part of any low carbon strategy), but in terms of modelling the refurbishment works:
    – in our Reference Case are we allowed to model the existing 90,000m2 of concrete structure, steel, linings, equipment and the like (on top of the new 5000m2 worth of refurbishment works) for the existing hospital only to have these 90,000m2 worth of existing materials removed from the Proposed Case?

    I suppose the project could have opted to build a new 5000m2 building that entails the extent of refurbishment works, but that doesn’t encourage reuse of the existing building.

    Any guidance would be appreciated

    Hi Max,

    With refurbishments and the reuse of existing buildings, usually the items that are worth ‘modeling’ would be items that would last the lifetime of the building (i.e. structural components) that won’t get replaced within the study period. This is because for the items that will get replaced within your study period, while they were retained from the original building, you will still have to account for the impacts of them getting maintained/replaced/repaired within the study period of the building. Although we encourage the reuse to existing materials, however to model this correctly would not only be complicated but ultimately the GWP savings from that would not really be worth the effort.

    For example, retaining plasterboard linings which have an assumed service life of about 45 years, would need to be replaced twice in a building study life of 100 years. So you would still need to account for the impact of the new plasterboard linings that was installed in later in the life of the building.

    I’m a bit confused about the GFA of your final building – is the final completed building going to be 90,000m2 or 65,000m2 or 155,000m2?

    For example, if your final completed building will be 90,000m2 but 60,000m2 is retained from the existing building. In your Reference Design, you model the whole 90,000m2 as a brand-new building and in your Proposed Design ‘scenarios’ you delete 60,000m2 of the structural components of the building to demonstrate the benefit of reusing the old building.

    In a different example, if your final completed building is 90,000m2 but your existing building is 100,000m2 and only 60,000m2 of the existing building will be retained. Which means that 40,000m2 of the existing building was demolished. You will still model it the same way as the above because the demolition of the 40,000m2 of existing building is out of scope for the new building’s study according to EN 15978.

    Hope that answers your question.

    Hi Fei,

    I’m still somewhat confused. Perhaps I’ll better describe the project details:

    – a new 60,000m2 GFA hospital building;
    – 5,000m2 refurbishment works (new flooring finishes, internal walls, ceilings, fixtures and fittings and equipment, and some infill concrete slabs) within the existing 90,000m2 hospital. So 85,000m2 of the existing hospital is retained, with 5,000m2 of refurbishment works.

    So for the existing hospital, I don’t know the service life of the existing materials (the existing building is approx 30 years old). But do I need to model the existing 85,000m2 concrete slabs in Reference Design, and can then delete these in the Proposed Design as they are being retained? Modelling that much existing/retained structure does impact

    With regards to the existing 85,000m2 building, do I add this area to the Project Functions to account for both retained and new floor area?


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