XLPE Foam is a closed-cell insulation material that can be suitable for selected HVAC and chilled-water applications where flexibility, moisture resistance and thermal performance are required. Nitrile Foam is another commonly used closed-cell elastomeric insulation material for HVAC and refrigeration applications. However, it should be selected according to the specific project requirements and applicable performance criteria. Glasswool and Rockwool can be used in appropriate cold-system assemblies, particularly where the overall system requires additional thermal, acoustic or fire-performance characteristics. Moisture and vapour control must be carefully addressed. Aluminium jacketing can provide mechanical and environmental protection for suitable exposed insulation systems. Insulation Thickness Matters More insulation is not automatically better. The required thickness depends on the operating temperature, ambient conditions, desired surface temperature and condensation-control requirements. For some systems, the objective may be to minimise heat gain. For others, preventing surface condensation may be the controlling design condition. The insulation thickness should therefore be determined as part of the complete system design.