When collecting data for eToolLCD there’s many directions or processes users take. There’s no “right” way. What is important is that the LCA is repeatable, so uses must ensure that the LCA study is repeatable, so the methods they used to collect data are documented (preferably using the “Docs” feature in the design). Below are some simplified workflows that summarise some of the common methods for collecting and entering data into an eToolLCD model. The yellow boxes are steps, the dark green diamonds are where a decision needs to be made and the green boxes are an end point (hopefully the data is in eToolLCD by this stage.
Remember, even when using a take off, try to relate this to eToolLCD templates so you pick up the construction (assembly) part of the equation (entering your raw steel amount from the take off, and then entering in a separate figure for crane, trades etc to install the reinforcement or structural steel is much more laborious than simply using an eToolLCD template for the installed steel quantity).
Once you’ve populated your design be sure to self check the Alerts and the Quality Checks. This can help identify missing items. The certification process with an eTool staff member will also help significantly.