Optimal insulation layer for heated water pipes under technical, economic and carbon emission constraints

Piping systems are a common element of thermal systems in several sectors. They usually have the function to deliver hot fluids for thermal processes and/or final uses, and they might be responsible for a large amount of heat losses, which results in higher primary energy consumption and carbon emissions, if adequate insulation layers are not designed and deployed. Finding the optimal insulation thickness is however not a straightforward process, since several technical, economic and environmental aspects enter into play. The present work investigates different optimisation approaches for determining the optimal thickness of insulation layers in civil and industrial piping systems, by introducing the concept of embodied energy and embodied carbon emissions of the insulation material, together with the economic evaluation of the investment associated with the insulation deployment. Several technical and economic characteristics are considered - e.g., pipe size, insulation materials, primary fuel, operating temperature, climatic conditions, fuel market price, country of origin of the insulation layer, etc. Results shows that the piping geometry, operating conditions and heating system strongly affects the optimal insulation thickness, while the climatic conditions have a little influence, especially for fluid operating temperature above 45 °C. Furthermore, the country of origin of the insulation strongly affects the net carbon savings achievable, due to the different embodied carbon emissions linked to the local energy mix used, and should be considered - e.g. by implementing a certification of origin mechanism, to correctly evaluate the emission reduction potential of the insulation layer deployment.