Thermal insulation of a building can be seen as an investment of money into something that is expected to yield a return. The cost of the insulation is the capital employed and savings in the future on heating bills are the return on the capital.

By using assumptions for the interest rate, pay back time and energy price escalation, optimum insulation thickness can be calculated. In most cases the optimum thickness is considerably above the level required by building regulations.

Other factors may also be taken into consideration in the calculation, such as the increase of the resale value of the property.

The scope of optimum insulation is to focus purely on the economic considerations of the first years of operation. Today, building products and solutions are increasingly evaluated based on Life Cycle Analysis (LCA). Costs are
evaluated throughout the entire life of the building.