Applicability The commissioning process described here applies to new construction@ major renovations@ and all systems and assemblies. Although this chapter focuses on HVAC@ commissioning can be applied to the building as a total system@ which includes structural elements@ building envelope@ life safety features@ electrical systems@ communication systems@ plumbing@ irrigation@ controls@ and HVAC systems (ASHRAE Guideline 0). Based on owners' preference and project contract scope@ total commissioning can include industrial process and process equipment@ systems@ piping@ instrumentation@ electrical@ and related control@ or these topics may be treated as an independent phase of project commissioning. Which building systems should be commissioned varies with the systems and assemblies used@ building size@ project type@ and objectives. Owners and commissioning providers often focus on systems and assemblies under the commissioning umbrella that have (1) historically not performed well at turnover (e.g.@ outside air economizers and variable-speed drives)@ (2) are mission-critical (e.g.@ air cleanliness in a cleanroom@ emergency power in a hospital)@ (3) will be costly to fix during occupancy if they fail (e.g.@ chilled-water piping@ window flashing assemblies)@ or (4) present a life-safety risk if they fail (e.g.@ fire alarm@ smoke control@ moisture penetration). Recommendations in this chapter should be appropriately modified for each project. Although commissioning may begin at any time during the project life cycle@ owners obtain the highest benefits when commissioning begins at the conceptual or predesign phase.