The chapter is essentially about energy conservation, the building envelope and its various components and systems, intelligent energy management systems, mechanical systems and types, electrical and lighting systems (interior and exterior), solar energy systems (active and passive), and fire suppression systems. It also gives an overview of the new LEED® V3 Rating system (including points allocation), particularly as it applies to the energy and atmosphere category and explains some of the new requirements to achieve LEED credits in this category. Diagrams and details are used to illustrate many of the systems and building components. An explanation of amps, volts, and watts is given as well as an overview of common electrical components, aluminum wiring, harmonics, as well as the components and types of solar electric systems. Likewise, the increasingly pivotal role fire protection systems play in overall building design and construction is clearly presented and the various systems and methods used are analyzed and explained. Relevant codes and standards are given at the end of the chapter. Keywords: Energy and atmosphere; LEED® EA prerequisites; building envelope; exterior wall systems; intelligent energy management systems; intelligent building; mechanical systems; refrigerants; HVAC systems; heat pump; air-conditioning systems; ASHRAE; MERV rating; lighting systems; electrical components; transformer; harmonics; solar energy; tax credits; fire suppression systems; sprinkler systems; exit routes; alarm systems; fiber optics