Building Performance: Glossary

Last updated: July, 2006

The field of building performance encompasses a wide array of approaches for testing and optimizing the energy performance of commercial buildings. This glossary contains definitions for terms associated with major methodologies used by program administrators and engineers. The definitions are gathered from key players in the field of building performance and authorities on commercial equipment, including the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE), the National Energy Management Institute (NEMI), Portland Energy Conservation, Inc. (PECI), and the National Academy of Sciences.

A - F | G - Q | R - Z

Automated Building Diagnostics Software

ABDS is an emerging Building Automation System (BAS) software that is designed to automatically perform building commissioning on an ongoing basis, reducing the need for full commissioning projects. The software has the capacity to provide continuous optimization and greater certainty through control, correction, and monitoring of a building's HVAC equipment.

Building Automation System

Also known as an Energy Management System (EMS), the BAS is a computerized system for fully automatic control of HVAC, lighting, refrigeration, and other building subsystems in order to accurately manage and monitor indoor temperature, comfort and environmental quality. A BAS often saves energy by allowing time-of-day scheduling and peak load shedding control.

Building Tune-up

A building tune-up is similar to retro-commissioning in that it is a way of effectively identifying and correcting systemic problems in an existing building's subsystems. But whereas retro-commissioning focuses on evaluating operating performance and making low-cost corrections and recommendations for optimization, a building tune-up goes one step further to contractually execute more extensive improvement and repairs. Priorities are set based on the highest impact improvements acheivable within the available budget.

Commissioning (Cx)

Commissioning is a risk reduction or quality assurance process for new construction projects that operates from pre-design through design, construction, and operations. The purpose of commissioning is to ensure that all components of a building have been designed, installed, tested, and are capable of being operated and maintained in conformity with the design intent. (ASHRAE, 1996) The process includes testing, documentationn, and training of operation and maintenance staff.

Commissioning Service Provider

The commissioning service provider, or commissioning provider, is often referred to as a commissioning agent, commissioning engineer, or commissioning expert. The commissioning provider is hired or assigned by the owner.

Continuous Commissioning

(see Ongoing Commissioning)

Enhanced O&M

Enhanced O&M practices are recommended to improve operations and maintenance based on a review of existing practices.

Ongoing commissioning

Ongoing commissioning or "continuous" commissioning is a practice consistent with the objectives of retro-commissioning but places a greater emphasis on addressing persistence issues within a building's operations. In addition to the tests administered under a retrocommissioning program, ongoing commissioning requires benchmarking the building's performance before and following the commissioning procedures, and subsequent continuous data collection over a specified period to ensure the building maintains optimized functionality over the course of its life.

Post-Occupancy Evaluation

Post-occupancy evaluation (POE) is a process of systematically evaluating the performance of buildings after they have been built and occupied for some time. POE differs from other evaluations of building performance in that it focuses on the requirements of building occupants, including health, safety, security, functionality and efficiency, psychological comfort, aesthetic quality, and satisfaction. “Lessons learned” refers to programs aimed at collecting, archiving, and sharing information about successes and failures in processes, products, and other building-related areas for the purpose of improving the quality and life-cycle cost of future buildings. Ideally, the information gained through POEs is captured in lessons-learned programs and used in the planning, programming, and design processes for new facilities to build on successes and avoid repeating mistakes. (National Academies Press, 2002)

Recommissioning

Recomissioning is conducted on a periodic basis in buildings that were either commissioned during construction or retrocommissioned during their life. The process reapplies the original commissioning tests, and is idealy part of an ongoing operations and maintenance program.

Retrocommissioning (RCx)

Retro-commissioning, or "existing building commissioning," is a process to ensure the functionality of a building that has not been previously commissioned. It is a systematic investigation of how a building's subsystems are being operated and maintained, and it is used to identify and solve optimization and integration issues. Retrocommissioning usually excludes retrofit solutions or major equipment replacements, although such recommendations may be offered.

Retrofit

A retrofit involves the installation of updated technologies into an older existing building. Retrofits often involve either structural enhancements to increase strength, or replacing major equipment central to the building's functions, such as HVAC or water heating systems.

Screening

Screening processes are used to identify bulidings that are likely to benefit from improvements to operating performance.

Scoping

Scoping studies identify technical opportunities for high priority buildings through providing an on-site review and subsequent recommendations for appropriate follow-on retrocommissioning activities.

Testing and Balancing

Testing, adjusting, and balancing is a methodology by which the heating, ventilation and air-conditioning (HVAC) systems and subsystems of a building are reviewed and corrected so that they perform at an optimimum level of efficiency consistent with the design intent of the system. Testing is the use of specialized instruments to measure temperature, pressure, rotational speed, electrical characteristics velocity, and air and water quantities for an evaluation of the equipment and the system performance. Adjusting is the final setting of the balancing devices; such as, dampers, valves, and automatic control devices like thermostats, pressure controllers, and computer controls. Balancing is the methodical regulation of system flows, whether they be air or water, through the use of acceptable procedures to achieve the specified flow quantities. (NEMI, 2005)

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