Abstract: A spa comprising a layer of copper-containing material, a layer of a cotton-containing material external to the layer of copper-containing material, wherein the layer of copper-containing material and the layer of cotton-containing material are at least partially located between outer spa frame studs, and a layer of at least one of a polyester or a polypropylene-containing material external to the layer of cotton-containing material. The layers of copper-containing material, cotton containing material, and at least one of a polyester or a polypropylene-containing material are located between a spa basin and a spa cabinet. The spa bottom may also have a layer of copper-containing material affixed thereon. In some embodiments, the spa may further comprise an insulated cover with a layer of copper-containing material therein.