Energy is one of the basic quantitative properties describing a physical system or object's state. It is the capacity of a system to do work. That system may be a jet, carrying hundreds of passengers across the ocean. A baby’s body, growing bone cells. A kite, rising on the wind. Or a wave of light crossing a space. In moving or growing, each of these systems is doing work, and using energy. Every living organism does work, and needs energy from food or photosynthesis (Wikipedia.com). Humans also create machines that do work for them, and that derive energy from fuels.
Energy can be transformed among a number of forms that may each manifest and be measurable in differing ways. The law of conservation of energy states that the energy of a system can increase or decrease only by transferring it in or out of the system. The total energy of a system can be calculated by simple addition when it is composed of multiple non-interacting parts or has multiple distinct forms of energy. Common energy forms include the kinetic energy of a moving object, the radiant energy carried by light and other electromagnetic radiation, and various types of potential energy such as gravitational and elastic. Common types of energy transfer and transformation include processes such as heating a material, performing mechanical work on an object, generating or making use of electric energy, and many chemical reactions (Wikipedia.com).
Efficient energy use, is the goal to reduce the amount of energy required to provide products and services (Api.org). For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature. Installing fluorescent lights or natural skylights reduces the amount of energy required to attain the same level of illumination compared with using traditional incandescent light bulbs. Compact fluorescent lights use one-third the energy of incandescent lights and may last 6 to 10 times...