As the insulation thickens, the heat loss decreases, but the investment cost increases. Economic insulation thickness is the thickness that minimizes the sum of the annual energy loss cost and the annual capital share of the insulation investment. This tool calculates standard thicknesses between 20–200 mm one by one and gives the lowest total.
Formula
N = i (1+i)^n / [(1+i)^n − 1]
V(L): insulation volume, q(L): heat loss at that thickness (W/m, TS EN ISO 12241), N: annuity coefficient for interest i and depreciation period n.
Example
For 100 m DN100 pipe carrying 10 bar(g) steam, the heat cost is 1.2 ₺/kWh, insulation + coating + labor is 25,000 ₺/m³, 6,000 hours per year, 10% interest and 5 years of depreciation, with an economic thickness of 60 mm rock wool. At this thickness, heat loss is 64 W/m and surface temperature is 39 °C. The annual savings compared to bare pipes are approximately 760,000 ₺, and the payback period is 1.3 months.
Prices are examples; enter your own fuel and insulation prices. You can find the unit cost of heat energy with steam cost or energy unit cost tools. To evaluate your steam system as a whole, you can take a look at our steam boiler guide and get a free quote for your project.