The value of the building is increasing at 8% per annum in real terms. Since the general rate of inflation is 2.5%, the actual rate of increase in the value is (1.025 x 1.08) – 1 = 10.7% Because the building is taking 12 months to build, the value will inflate for 5 years, not 6.
So the terminal value = 6.2M x 1.107^5 = 10,306,941
The charge for repair and renewals is given at current prices, so the actual/nominal cost is 1.2M x 1.025^6 = 1,391,632
So the net cash flow = 10,306,941 – 1,391,632 = 8,915,309 (which is the figure in the answer – you accidentally mistyped it in your posting).