To demonstrate how a sustainable home can be constructed, Duke University in conjunction with Home Depot has built a sustainable "smart home" demonstration. It has received a LEED (Leadership in Energy and Environmental Design) platinum rating, the highest level rating. It includes solar water panels for hot water heating, 18 photovoltaic solar panels that generate 3 kW of electricity, a vegetated green roof planted with sedums that are drought tolerant and capture and filter rainwater while providing roof insulation, rainwater collection for irrigation of the grass of the site, Energy Star appliances, and recycling of construction waste materials.