15.1. Lecture exercise

Note

The calculations serve as examples for educational purposes and not as guidance for practice.

Note

This exercise shows some of the basic principles of an LCA. It serves educational purposes and should not be used for guidance in practice. The lecture, which covered this example, was given in the course Sustainable Construction Members in the Master Civil Engineering, track Structural Engineering, by Henk Jonkers in the academic year 2023-2024.

Goal

Calculate ECI value for materials (LCA module A1-A3) used for construction and transportation (LCA module A4) and construction processes (LCA module A5) of a concrete water reservoir (thus construction phase only), and determine which input variable (material or process) contributes most to the construction stage ECI value, and give advice on options on how the ECI value can possibly be decreased.

Data

The necessary materials and processes of the required LCA modules are given in Table 15.1.

Table 15.1 Materials and processes amounts and distances

Inputs	Quantity	Unit	Distance	Unit	Required Quantity	Unit
Concrete	7.56E+05	[kg]			7.56E+05	[kg]
Steel	1.73E+04	[kg]			1.73E+04	[kg]
Sand	1.20E+05	[kg]			1.20E+05	[kg]
Truck mixer	3.15E+02	[m^3]	45	[km]	1.42E+04	[m^3*km]
Lorry	1.73E+01	[ton]	125	[km]	2.17E+03	[ton*km]
Welding casting	2.88E+02	[h]			2.88E+02	[h]

The impact categories per materials and process are given in Table 15.2.

Table 15.2 Impact categories per material/process

Inputs	Unit	GWP	HTP	AP
Concrete	[kg]	0.0921	0.0102	0.0002
Steel	[kg]	1.79	3.81	0.0074
Sand	[kg]	0.0025	0.0017	0.0001
Truck mixer	[m^3*km]	0.22	0.04	0.0013
Lorry	[ton*km]	0.13	0.038	0.0007
Welding casting	[h]	43.3289	27.4484	0.3335

Total shadow costs are set to the following per unit of input:

• GWP: € 0.05

• HTP: € 0.09

• AP: € 4.00

Questions

1 What is the total (construction) environmental cost (ECI value) of the concrete water reservoir?

Solution

By multiplying the materials and processes data from Table 15.1 with Table 15.2 and its corresponding shadow costs, the costs per material/process can be calculated, displayed in Table 15.3.

Table 15.3 Cost per material/process

Inputs	Unit	EUR/input	GWP	HTP	AP
Concrete	[kg]	€ 4,780.19	0.0921	0.0102	0.0002
Steel	[kg]	€ 8,004.15	1.79	3.81	0.0074
Sand	[kg]	€ 81.36	0.0025	0.0017	0.0001
Truck mixer	[m^3*km]	€ 280.67	0.22	0.04	0.0013
Lorry	[ton*km]	€ 27.55	0.13	0.038	0.0007
Welding casting	[h]	€ 1,719.59	43.3289	27.4484	0.3335

The total costs can now be summed and amount to € 14,893.50.

2 Which two inputs (materials or processes) contribute most to the total environmental impact?

Solution

Steel the most, concrete 2nd

3 Suggest two measures which can be taken to lower the impact most effectively?

Solution

• Make a more efficient design that creates less tensile forces, thereby requiring less reinforcement steel

• Use another form of concrete, geopolymer concrete