As we know, our planet is experiencing global warming. We are all being asked to save electricity, but this isn't always easy. We can't have every light turned off, or every heater turned off, or every air conditioning unit turned off. Luckily, skylights allow us to substitute all three of these with one simple, unit: a skylight. The cost of a skylight, and installing it probably won't go above $2000, and it can replace many of the functions that lights, heaters, and ACs provide. Firstly, light. skylights give light by letting sunlight in through the roof, allowing illumination to continue for the whole day. What about heaters? The constant illumination provided by a skylight raises the temperature of the air in a room, causing the room to become much warmer, and the heat is kept in by the skylight, causing a localized greenhouse effect. But surely this cannot act as an air conditioner. It can - having the skylight open still lets the sun heat up the air, but the air rises through the open skylight, causing a breeze when the windows are open, consequently cooling the air in the room and acting like an air conditioning unit. So, if you're looking for a good way to help the earth and save some energy and money for yourself, you may want to try out a skylight. They really are very effective, especially in large rooms, unlike conventional appliances, as skylights rely on air currents.