Sprayed foam insulation, which may be soft or rigid, is forecast to replace fibreglass for thermal insulation applications. The rigid material has a lower permeability, so reducing the passage of moisture. The R-value of rigid foam is approximately twice that of soft foam. The sprayed systems are water-based, and some are manufactured from renewable agricultural resources. They produce no harmful emissions, and the spraying process enables the filling of all cracks and gaps. The material cost may be 10-15% more than fibreglass, but construction costs are less and the superior insulation properties may allow a reduction in the size of HVAC systems.