Construction Energy

  • We received this question today and wanted to share this on the forums as it’s possibly a pretty common query:

    I would have a few questions for you:
    – Construction energy: we had discussed using an electrical equipment in a template to be able to add a single energy use figure during construction (instead of each equipment and program). I created the template. Only issue I have is that I could not find an equipment without any transport impact. The impact is not massive, but would like to know how to remove this from my template.
    Construction water: Same as above, I would like to add a figure for construction water, but I could not find water use equipment to do the same as construction energy. How do you usually had water use during construction?
    Renewable energy: We discussed this already, but I am working on a project that will use only GreenPower during operation. Is there a way to get the renewable energy grid, just like we select the “NWS electricity” in the project settings?

    Answers to follow…

    Construction Energy: So I’m guessing this is energy relating to site offices etc? Of some other kind of equipment that is not transported to and from site. The best workaround here would be (ironically) selecting “offsite manufacturing process” as this won’t have transport impacts like other construction equipment. The unit is actually kWh. However I recommend voting on this feature request for a better long term solution to this:

    Construction Water: Again the long term solution is addressed with the feature request but the workarounds available are:

    • Use the “Construction Water Use” template which unfortunately adds the impacts to the A1-3 module rather than A5
    • Create an EPD with the water use impacts allocated to module A5

    Renewable Energy: Green power is discussed at some length in this post:  We don’t recommend accounting for Green power in the headline LCA results due to the risks of double counting.  However, if you did want to run that scenario to demonstrate to the design team at the very minimum I think you should be reporting this “credit” in module D and limiting the size of the credit to the length of time the PPA is signed for.  To do this, enter all your energy items selecting the most appropriate grid.  Add another energy item and enter a negative quantity that is equal to the sum of the demand and allocate this to module D (this cancels out the normal energy use).  You then need to add the impacts of the green energy supply to module D, there’s a few options:

    • If you know where the energy is coming from you can another energy item (or another source to the existing one) and change the “Delivery Method” to “Other” in place of “distribution grid” and then select, for example, “Electricity from Wind” as the energy source.  Enter in a positive quantity equal to the sum of the demand and allocate to module D.
    • Ask the energy supplier for an EPD or manually calculate the energy supply impacts.  Create your own custom EPD and enter the impacts of the green energy into Module D1 (remember to enter the non-GWP impacts as well)

    You could also just deal with the Greenhouse Gas (GWP impacts by creating a custom EPD with a negative GWP impact in module D1 equal to the combustion GWP impacts of the grid of the project (i.e. not life cycle impacts which include infrastructure such as poles and wires).

    For those that need to consider preliminary aggregated construction impacts (A5) following the RICS guidance, this proxy EPD can be used:

    EPD created for preliminary input of construction impacts under modules A5, following the RICS guidance when limited info is available. This aggregated impact based on expenditure (1.4 tCO2/£100k) includes various items like temporary energy consumption, plant use, waste and they all need to be split into individual templates as the design progress and more detailed information becomes available.

    Update: construction energy and water can now be added directly into A5 under the equipment category. This can be done either within templates in the library or directly in the equipment category within models. There are now equipment items for:
    – ‘diesel combustion in construction’ (L)
    – ‘electricity use in construction’ (kWh)
    – ‘biodiesel combustion in construction’ (L)
    – ‘petrol combustion in construction’ (L)
    – ‘natural gas combustion in construction’ (m3)
    – ‘vegetable oil combustion in construction’ (L)
    – ‘potable water use in construction’ (kL)

    Please log a support request if you would like any other construction energy items added to the equipment library.


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