What is effective age?

In the cost-depreciation approach to valuation, effective age is a term used to describe the appraiser’s estimate of the physical condition of a building

For example, a warehouse was completed in 2002; it has been immaculately maintained and looks almost new

In 2012, an appraiser, using his professional judgement, considers that the physical condition of the building is as he would expect to see in a warehouse that was built 5 years ago

In the opinion of the appraiser, the effective age is judged to be 5 years, even though the chronological age of the warehouse in 2012 is 10 years