The cost approach was once called the summation approach. The theory is that the value of a property can be estimated by summing the land value and the depreciated value of any improvements. The value of the improvements is often referred to by the abbreviation RCNLD (for "reproduction/replacement cost new less depreciation"). Reproduction refers to reproducing an exact replica; replacement cost refers to the cost of building a house or other improvement which has the same utility, but using modern design, workmanship and materials. In practice, appraisers almost always use replacement cost and then deduct a factor for any functional dis-utility associated with the age of the subject property. An exception to the general rule of using the replacement cost is for some insurance value appraisals. In those cases, reproduction of the exact asset after a destructive event like a fire is the goal.