Abstract This chapter is divided into three sections: energy efficiency in compressed air, energy efficiency in ventilation, and energy efficiency in lighting. In the section about compressed air, the reader is first introduced to the fundamentals of compressed air, such as the parts of the compressed air system, such as compressors. The subsection summarizes examples of possible measures when auditing compressed air systems before presenting nonenergy benefits when making modifications and investing in compressed air. In the section about ventilation, the reader is first introduced to the fundamentals of ventilation such as the parts of the ventilation system, such as ventilation units. The subsection summarizes examples of possible measures when auditing ventilation systems before presenting nonenergy benefits when making modifications and investing in ventilation improvements. In the section about lighting, the reader is first introduced to the fundamentals of lighting such as the parts of the lighting system, such as fixtures. The subsection summarizes examples of possible measures when auditing lighting before presenting nonenergy benefits when making modifications and investing in lighting improvements.