Factory-built homes have the benefits of being constructed inside a manufacturing plant (avoiding weather-related delays), standardization that improves consistency and eliminates waste, and a design/build process that facilitates innovation and quality control. These characteristics allow manufacturers to produce high-quality housing much more quickly and cost effectively than homes that are site-built. Manufactured housing is the largest source of unsubsidized affordable housing in the United States, but most manufacturers are not using the most advanced energy-saving designs and technologies that could reduce monthly energy costs.