Weatherization is distinct from building insulation, although building insulation requires weatherization for proper functioning. Whereas insulation primarily reduces "conductive" heat flow, weatherization primarily reduces "convective" heat flow. Local grantees have the option to use Weatherization funds to support appliance purchases. Increased energy efficiency and weatherization spending has a high return on investment. Niagara Conservation also manufactures lighting fixtures, light bulbs, caulks, sealants, and weatherization products. The Weatherization article describes methods for energy savings further. This typically includes painting, minor exterior repairs, landscaping, weatherization and exterior clean-up. However, unlike weatherization programs, the gains in household budgets are often not worth the investment. Occasionally, acceptance of the weatherization process is mandatory with approval for LIHEAP assistance. Weatherization has become increasingly high-profile as the cost of home heating has risen. The auditor is trained to determine the most cost-efficient weatherization measures for the home. A hundred million American buildings still need improved weatherization. All paving stones have been treated with a thermal coating to help them resist weatherization. Consequently, after weatherization, concentrations of indoor air pollutants from sources inside the home can increase.