a. Window frames are made from extruded aluminium. It is argued that making them instead from extruded PVC would give a product with a lower embodied energy and carbon footprint. If the section shape and thickness of the aluminium and the PVC windows are the same and both are made from virgin material, is the claim justified? You will find embodied energies and densities for the two materials in the data sheets of Appendix A, Tables A2 and A10. Use the mean values of the ranges given there.

b. Products like window frames would more usually be made from recycled aluminium. If the embodied energy of recycled aluminium is \(30 \mathrm{MJ} / \mathrm{kg}\), does the conclusion change?

Data From Appendix Table A10

Data From Appendix Table A2

Table A.10 Embodied Energy, Carbon Footprint and Water Demand