Valuations utilize significant unobservable inputs (level 3) when determining the fair value of sustainable resource assets. The  significant level 3 inputs include: Valuation technique(s) Significant unobservable input(s) Relationship of unobservable input(s) to fair value Discounted cash flow models • Future cash flows – primarily  driven by avoided cost or  future replacement value • Increases (decreases) in future cash flows will  increase (decrease) the fair value • Discount rate • Increases (decreases) in discount rate will decrease  (increase) the fair value • Terminal valuation date • Increases (decreases) in terminal valuation date will  decrease (increase) the fair value • Increases (decreases) in the exit date will decrease  (increase) the fair value Key valuation assumptions included a weighted average discount rate of 7% (2012 – 6%), and a terminal valuation date of 3 to  35 years (2012 – 3 to 35 years). The following table presents the changes to the cost of the company’s sustainable resources property, plant and equipment assets: The following table presents the changes to the accumulated fair value changes of the company’s sustainable resources assets: The following table presents the changes to the accumulated depreciation of the property, plant and equipment within the  company’s sustainable resources business: The company’s property assets include hospitality assets accounted for under the revaluation model and the most recent date of  revaluation was December 31, 2013. The company determines fair value for these assets by discounting the expected future cash  flows using internal valuations.  122 BROOKFIELD ASSET MANAGEMENT  YEARS ENDED DECEMBER 31  (MILLIONS) 2013 2012 Balance at beginning of year  $ 1,461 $ 1,339 Disposals, net of additions  (784) 139 Foreign currency translation  (11) (17) Balance at end of year  $ 666 $ 1,461 YEARS ENDED DECEMBER 31  (MILLIONS) 2013 2012 Balance at beginning of year  $ (18) $ (132) Fair value changes  49 142 Dispositions  133 — Foreign currency translation  1 (28) Balance at end of year  $ 165 $ (18) c) Property YEARS ENDED DECEMBER 31  (MILLIONS) 2013 2012 Balance at beginning of year  $ (31) $ (12) Depreciation expense  (3) (20) Dispositions  3 — Foreign currency translation  1 1 Balance at end of year  $ (30) $ (31) (MILLIONS) Dec. 31, 2013 Dec. 31, 2012 Cost  $ 3,168 $ 3,130 Accumulated fair value changes  170 4 Accumulated depreciation  (296) (166) Total  $ 3,042 $ 2,968