Unlike many other architectural styles, green simply refers to the building approach and materials that minimize the harmful effects to the environment, with a goal of being fully sustainable. This style often has large windows to maximize natural lighting and reduce energy consumption. Low-emittance (low-E) windows keep the heat inside in winter and outside in summer. Non-synthetic, non-toxic or recycled materials are often used in conjunction with locally obtained woods or stone. Ventilation system typically differs from traditional building practices, to optimize heating and cooling. Landscapes are planned to maximize passive solar energy using plants fit for a specific region.