Sustainable design is a way of designing the things we use so they take less energy and resources to make, use less energy and resources, and last longer. It also includes making sure the things we use don't cause harmful damage to our environment. For example, buildings can have better insulation that helps keep the heat or cold in, so you don't have to use as much energy for heating or cooling. When making furniture or items, designers can use materials from recycled things (like bottles) and use special coatings to make them last longer, reducing the amount of new materials and energy used. Sustainable design also looks for ways to help people share items (like bikes or toys) instead of each person needing their own.