Hello everyone. I’m working on a project in the UK in which we’re interested in conducting a whole life carbon assessment (RICS) in OneClick LCA. My experience with OneClick so far has solely been focused on phases A1-A3 of building materials. I’d like to get an understanding of how I can go about estimating the energy consumption, water consumption, and construction site operations to complete the carbon assessment.
Has anyone ever gone through this process in the schematic design phase? Are there any guides available on how to go about completing these sections (aside from the OneClick guide)? Is there even any value estimating these parameters at such an early stage of the project when there are so many unknowns?
Hi Natasha,
You could make an estimation but why not go for the real thing: measure it!
My firm Turner Construction started measuring our on site energy and water use in early 2019 as part of your commitment to 2030 goals. We have learned a lot in the past couple of years, it was well worth it. In the program we measure, electricity use in the field and for our temp office + water use + collecting on site equipment fuel consumption data. Since we have multilpe projects we use a cloud platform for aggregating and visualize the info (BuildingOS). It may sound complicated but it is better and much more accurate than the alternative - estimating.
If you still must come up with an estimate you need a list of all planned on site equipment and find out their energy use. Material hoist, crane(s) are easy as they have reliable data the wild card is the on site equipment backhoes, trucks, light towers, generators, etc. What further complicates this method that most equipment remains idol for a good amount of time so estimate will wildly vary on the idling factor you elect to use.
At any rate do your best - anything you do is a positive step forward from the not knowing!
Good luck - Joseph
For such estimates, you can go with either SAP calculations (for residential) or SBEM (for non-residential). This is where the energy data should be taken from. Follow the methodologies and you should be able to move forward.
For water emissions, you can use BREEAM or Building regulation calculations.
In One Click LCA, there are also scenarios for site impacts for the early stages.
I have a fair bit of experience delivering WLC to RICS via One Click. For a RICS calc, I mostly only use One Click for A1-A4, B4 and C1-C4 outputs. I then export the data to excel and complete the rest of the RICS process manually as One Click is not yet perfectly set up to deliver it (i.e. there are various steps required by the assessment methodology that you cannot yet take in One Click). Most answers to your questions are in the RICS document.
Your operational energy data should be taken from the most robust methodology available - this should really be an advanced DfP energy modelling process such as CIBSE TM54 which captures both regulated and unregulated energy consumption. Part L outputs are ok but only so long as you very clearly state this is what you have used. Industry is now well aware of the restrictions and issues with Part L, so by using it you actually skew the proportional embodied-operational split in a building, where this should be as accurate as possible. You need to know energy consumption over your RSP from the different fuels and apply the correct carbon factors. You can then use RICS Section 3.4.2 to find the NG FES document, estimate the diminishing carbon factors over time and apply this as your separate decarbonisation model.
For water, what Vasilis said. Otherwise you can use the Better Building Partnership’s REEB Benchmarks (released earlier this year), which will allow you to estimate average water consumption. These are actual water consumptions from POE based on hundreds of assessed buildings of various types and give ‘standard’ and ‘good practice’ values which can be used. Search online and find the UK Gov carbon conversion factors for water supply and treatment, and then a bit of research will give you an idea of proportionally how much water is removed from the building. You’ll then have all you need.
Joseph’s model for site operations seems like it would be the most accurate, based on a more detailed assessment of site activities. However, if you don’t have that to hand or are in early stages, use RICS PS Section 3.5.2.2 which tells you how to calculate. You don’t input this to One Click, its added separately. Cost plan is one of the most critical items for a RICS PS assessment so you should be able to make this estimation in accordance with the calculation rules fairly easily.