Carbon dioxide (CO2) levels are an indicator of ventilation effectiveness inside buildings. CO2 concentrations greater that 530 ppm above outdoor CO2 conditions generally indicate inadequate ventilation. Absolute concentrations of CO2 greater than 800 to 1000 ppm generally indicate poor air quality for breathing.

Cogeneration is the simultaneous production of electrical or mechanical energy (power) and useful thermal energy from the same fuel/energy source such as oil, coal, gas, biomass, or solar panels. Conventionally, heat is emitted through cooling towers or flue gas is lost, but cogeneration makes use of that heat.

Commissioning (Cx) is the process of verifying and documenting that a building and all of its systems and assemblies are planned, designed, installed, tested, operated, and maintained to meet the owner’s project requirements.

Commissioning Authority (CxA) is the individual designated to organize, lead and review the completion of the commissioning process activities. The CxA facilitates communication among the owner, designer, and contractor to ensure that complex systems are installed and function in accordance with the owner’s project requirements.

Commissioning Process is a systematic quality-focused effort to ensure that building systems are designed, specified, procured, installed, and functioning in accordance with the owner’s intent. The process uses planning, documentation, and verification of testing to review and oversee the activities of both designer and constructor.

Commissioning Team includes those people responsible for working together to carry out the commissioning process.

Curtain walls protect a building from air and water infiltration. A glass curtain wall allows daylight in while reducing infiltration. A glass curtain wall can be fitted with operable windows or vents.