Many of our users have been asking us how to model construction waste that gets diverted from landfill (for recycling or energy recovery etc) in eTool. Intially there wasn’t an easy way to do this however we’ve now developed the following method to help our users to do just that!

Firstly, please keep in mind that the ‘Construction Waste Factor’ field under the materials’ input is very different from ‘Disposal or Recovery Method’ field. One relates to the material procurement stage and construction impacts (LC Modules A); while the other relates to the End-Of-Life disposal or recovery methods. If at the end of life, the material is put into landfill (the typical default industry average assumption), the impacts will be allocated to LC modules C; whereas if it’s recycled, the impacts/benefits associated with that will be allocated to modules D.

You WON’T need to change the materials’ Construction Waste Factors to model this strategy.

In this post, we’re specifically talking about the Construction Waste impacts related to Modules A and how we allocate the impacts/benefits of diverting that waste from landfill.

---

First thing to note, our typical construction waste factors for the most common construction materials are:

• Asphalt: 10% (m3)
• Bricks: 5% (m3)
• Concrete: 10% (m3)
• Steel: 5% (kg)
• Timber: 15% (m3)

Next the steps are as follows:

Method 1: Material Inventory Summary

1. Calculate the amount of construction waste your project has generated:
   • Generate the ‘Materials Inventory Summary’ report.
     
   • Your report should look something like this:
     
   • Based on the volumes/kg in the report for the main construction materials, calculate the amount of construction waste generated for your project. For example, out of 0.5m3 of asphalt, with a 10% construction waste factor, 0.05m3 of asphalt is wasted in your project. So the total amount of construction material wasted in the above summary table is 0.05m3 of asphalt, 0.025m3 of bricks, 0.0419m3 of concrete, 50kg of steel and 0.19995m3 of timber.
2. Find out what percentage is diverted from landfill for your project. Usually there is a waste management contractor that can provide you with these figures (estimated or actual). Apply these diversion factors to your total construction waste amounts. Like for example the table below:
   
3. With the quantities above, add the relevant EPDs from the EPD library.
   

---

Extracting Construction Waste Quantities Workaround

We developed two alternative methods for extracting construction waste quantities when the Materials Inventory Summary report was experiencing issues. Fortunately, we’ve since fixed these issues, making the Materials Inventory Summary report the most convenient method for extracting this information. However, we’ve decided to keep the explanations of the two alternative methods here to provide users with options that best suit their preferences.

Please follow the instructions below as a work-around for pulling out the material quantities to calculate the amount of construction waste generated for your project:

Method 2: Bulk Swap tool

1. Use the ‘Bulk Swap’ tool to filter out your different materials.

2. Copy and paste the relevant items into a spreadsheet.
   

3. In the spreadsheet, you’ll need to collate and edit the data so that it’s relevant for your design.
   
4. With the final total figures, you can calculate the amount of construction waste generated for your project. For example, according to the spreadsheet above, out of 29.43 tonnes of steel, a 5% construction wastage will be 1,471.5kg of steel while 17.19m3 of concrete is construction waste.
5. Find out what percentage is diverted from landfill for your project. Usually there is a waste management contractor that can provide you with these figures (estimated or actual). Apply these diversion factors to your total construction waste amounts.

6. With the quantities calculated, add the relevant EPDs from the EPD library

Alternatively, you can also use the ‘All Impact Details’ spreadsheet and use the ‘Data Tab’ sheet to filter out the materials and calculate the construction waste generated.

Method 3: All Impact Details report

1. Generate the ‘All Impact Details’ spreadsheet.
   
2. Click on the ‘Data Tab’ sheet.
   
3. Filter out the materials.
   
4. Hide irrelevant columns and collate your data accordingly. You may still need to dive into some of the templates to find the correct data as mentioned in the previous steps.
   

---

 

And that’s it! You don’t need to delete anything or change anything else in the design. The EPDs will take into account the benefits of the waste diversion for you.