I've not seen your assignment but I'd answer as below but you should alway discuss with your lecturer to ensure your on the right track.
Please do not quote these figures I have made them up.
Example:
Low carbon hempcrete wall £160 per meter square, thermal performance : U value 0.07 W/mK
Brick and block wall £120 per m2, U Value 0.18 W/mK
The lower the U-value of an element of a building's fabric, the more slowly heat is able to transmit through it, there the material is a better insulator.
I'd do a table of various elements, i.e wall, floor, roofs etc... form a comparison. including the pros and cons of each technique.
For extra marks I'd do a cost analysis of capex vs opex say on a mock house.