Trends in architecture have moved to hot outdoor designs that claim to have low maintenance and high style. Marcus Hiles has witnessed the rise in demand for open-air spaces that are sustainable and decrease costs. Ecological, conservation-minded choices such as rainwater/graywater harvesting and permeable pavement are leading the way. Using a rooftop collection structure, rainwater harvesting sends moisture from the air for storage in a well to be treated and reused on-site; graywater takes previously used home wastewater and redirects it for rest rooms and non-drinking purposes, decreasing the need for fresh water and dropping the amount of purification. A different apparently novel idea for environmentally minded construction, permeable paving, actually goes back thousands of years to the time when people first made roads by putting stones in beds over the ground. The method allows the rain to pass through small openings between four layers of filtration (paving material, gravel, fabric, sand) before becoming absorbed by the earth below. Its benefits include lowering runoff and pollution, controlling the flow of storm water to gutters and drains, replenishing local groundwater supplies and providing a skid resistant surface for walkways, patios and driveways; their many attractive patterns often incorporate crushed stone, brick, and recycled concrete.