Excellent insulation is critical to your walk in cooler, for keeping both temperatures and electricity bills low. Insulation is measured by its “R value” per square inch - the higher the value, the more effective the insulation. The industry standard for walk-in coolers is an R value of 25. Going up to R30 will save you even more money, especially if you are keeping your cooler at 40°F or below. We recommend using rigid foam insulation whenever possible - polyisocyanurate on the walls and ceiling, and extruded polystyerene (XPS) on the floor.