Architectural trends are currently highlighting outdoor designs which boast low maintenance and high style. Marcus Hiles, CEO of Western Rim Properties, has seen rising demand for open-air spaces that are both sustainable and reduce costs. Eco-friendly, conservation-minded choices such as rainwater/graywater systems and permeable pavement are picking up steam around the country. Using a rooftop collection system, rainwater harvesting redirects rain falling on the building to a well to be treated and reused on-site; while graywater utilizes dirty domestic waste water and recirculates it for restrooms and other non-drinking purposes, cutting the need for sterilized fresh water. Another modern concept for environmentally minded construction, permeable paving, actually dates back thousands of years to the time when people first created roads by placing stones in beds over the ground. The practice allows rainwater to pass through small cracks and pass through more than three layers of filtration (paving material, gravel, fabric, sand) before becoming absorbed by the earth below. This process reduces runoff and pollution, controls the flow of storm water to gutters and drains, restocks local groundwater supplies and also provides a skid resistant surface for walkways, patios, and driveways. Many attractive patterns of permeable pavement often incorporate crushed stone, brick, and recycled concrete.