Based on the Tutorial Question below, please investigate and comment that how the variations of the "annual fuel-saving" and "annual maintenance fee" will affect the results of this tutorial question. Using the "annual fuel-saving" varies +/- 0~200 HK$ based on the original 3000 HK$/year, and the "annual maintenance fee" varies +/- 0~50 HK$ based on the original 100 HK$/year as examples.

Tutorial Question 2: An alternative solution for the building project mentioned in the Tutorial Question 1 is to invest a solar thermal heating system. The initial investment is 23 600 HK$. The annual fuel saving is 3000 HK$Iyear, while the annual maintenance fee is 100 HK$Iyear. The salvage value is zero. The life-time of this solar heating system is also 20 years. The interest rate is 10%. (1) Please calculate the NPV of this solar heating system. (2) Please use the incremental BCR method to compare this solution with the ground source heat pump solution introduced in the Tutorial Question 1. Which one is superior