Problem 8-26 Investment Criteria (LO1, LO2, LO4) If you insulate your office for $18,000, you will save $1,800 a year in heating expenses. These savings will last forever. a. and b. What is the NPV of the investment when the cost of capital is 4%? What if it is 10%? Cost of Capital a. 4% b. 10% NPV c. What is the IRR of the investment? Note: Enter your answer as a whole percent. IRR % d. What is the payback period on this investment? Payback period years