Insulation thickness in the ROGTech calculation program

Open a browser and search for 'ROGTech' on Google. Click the result shown, then select 'Read more' or the direct link to the calculator itself to get to the spreadsheet.

At the top of the calculator you choose whether you are working with a pipe diameter (plumbing pipe) or a circular duct (ventilation). Note that the flow velocity field is only available for circular ducts — it disappears when you select pipe diameter.

Enter the pipe diameter — the example uses a 60 mm pipe. Then enter the medium temperature (65 °C) and the ambient temperature (20 °C). These three parameters form the basis for all further calculations.

Under product selection, you choose the insulation product to be used. In the example, a universal pipe section is used. The product choice determines which thicknesses the calculator can suggest.

Select the system type that suits the installation. If you choose, for example, 'Heating system — distribution lines, heating season only with controlled temperature', ROGTech places the pipe in class 3. The class determines the insulation thickness required by the standard.

Select the emissivity for the insulated surface. If a shiny aluminium cladding is used, 'shiny' can be selected, but this assumes that the customer maintains a shiny surface. As standard, 'aluminium, oxidised' is recommended. For the pipe itself (uninsulated), enter the emissivity for a black steel pipe.

Select whether the pipe is located indoors or outdoors (here indoors, given the ambient temperature of 20 °C). Enter the orientation — horizontal or vertical — depending on where most of the run is. Then select the support type: according to the programme, an uninsulated support results in a 5 % increase in heat loss and may require a greater insulation thickness than an insulated support.

Click 'Calculate'. ROGTech shows the calculated required insulation thickness. In the example, the calculation gives 33.9 mm, but as this dimension is not commercially available, it is rounded up to the nearest available thickness of 40 mm. If an uninsulated support is used, the requirement rises to 50 mm.

Review the calculation results: the surface temperature of the insulation will be 27.9 °C with 33.9 mm insulation, but falls to 26.9 °C with the 40 mm actually fitted — i.e. 1 degree lower. The heat loss with insulation is 12.3 W/m, while an uninsulated pipe gives off 104.1 W/m.

ROGTech also calculates the required centre distance (G) from wall/ceiling to the centre of the pipe, which is given here as 120 mm. If two pipes are to run side by side with a permitted clearance of 50 mm after insulation, the centre-to-centre distance must be at least 95 mm.

Switch from 'class' calculation to 'operating time' calculation to base the result on actual operating hours. For example, enter 4,300 hours per year for a heating season and click 'Calculate'. The result here shows an insulation thickness of 40 mm. At 4,400 hours the requirement rises to 50 mm — an example of how accurate recording of operating time can have a direct impact on the chosen thickness.

Click 'Calculate by thickness', and re-enter the known parameters: 60 mm pipe, 65 °C medium temperature, 20 °C ambient temperature, 40 mm insulation thickness and product choice. Then enter the number of running metres of pipe (here 12 m), energy unit (kWh), energy price (2.25 kr./unit) and number of operating hours per year (4,300 hours). Press 'Calculate saving' to see the result.

ROGTech now shows the complete calculation report with insulated heat loss (12.3 W/m), uninsulated heat loss (104 W/m) and the calculated monetary saving. In the example the saving amounts to DKK 10,658 per year for the 12 running metres of pipe. This figure is a strong sales argument with the customer.

Select the double-layer calculation function with the same pipe diameter and temperatures. Enter the first layer as e.g. a 20 mm universal pipe section and the second layer as e.g. a 20 mm lamella mat. Click 'Calculate'. ROGTech now calculates the surface temperature between the two layers and the temperature of the outermost surface.

The result shows that the surface temperature of the pipe drops from 65 °C to 42 °C once the first 20 mm layer has been applied. After the second 20 mm layer has been fitted, the surface temperature falls further to 27 °C. These figures document the effect of each individual layer and can be used in design and advisory work.

Enter the calculation date and job name directly in ROGTech so the calculation is saved in the program's database. You can then always find the job's folder again and adjust parameters if the assumptions change.