Sustainable design, also known as 'green building,' is an alternative to conventional design and construction. Buildings that incorporate sustainable strategies use fewer natural resources, require less energy, save money and create environments that protect human health. For these reasons, sustainable design is fast becoming the reference for smart development, and inspiring new interest in what makes a building 'green.' Deciding this requires complex trade-offs, and in the absence of an accepted definition or standard for 'green,' buyers and consumers might easily be misled by 'greenwashing,' or exaggerated and unverified claims. To address this problem, the u.s. green building council created the leed (leadership in energy and environmental design) rating system.