Is retro-commissioning the same as an energy audit?

No. An energy audit identifies efficiency measures across a building, including equipment replacements and other capital upgrades. Retro-commissioning concentrates on how existing equipment and controls operate, uses functional testing and trend data to find problems, and carries the corrections through implementation and verification. New York City's Local Law 87 requires both, which is why owners there often procure the two together.

How often should a building be recommissioned?

The ENERGY STAR Building Upgrade Manual says recommissioning is normally done every three to five years, and sooner when energy use rises or comfort complaints increase. Laws that mandate the process set their own cycles: every five years under Seattle's Building Tune-Ups and Philadelphia's Building Energy Performance Program, and every ten years under New York City's Local Law 87.

How much energy does retro-commissioning save?

Lawrence Berkeley National Laboratory's 2020 analysis of commissioning in existing buildings found median primary energy savings of 5 percent for projects in utility programs, 9 percent for monitoring-based commissioning in utility programs, and 14 percent for projects outside utility programs, with a median simple payback of 1.7 years. Individual results vary widely with the building's starting condition and with how many of the recommended measures the owner implements.

Does retro-commissioning require new equipment?

Rarely. Most findings are corrected in the building management system: a schedule, a setpoint, a reset strategy, or a control sequence. Some findings require repairs, such as replacing a failed damper actuator or a drifted sensor. Equipment replacement falls outside the usual scope, and owners handle it as a separate retrofit project.

How does functional testing work in retro-commissioning?

A functional test drives a piece of equipment through its operating modes and records whether the equipment responds as its sequence of operation requires. A provider might command an air handler from occupied to unoccupied mode, or force an economizer into free cooling, and observe dampers, valves, and temperatures. Functional testing finds problems that trend data alone cannot show, because some operating modes occur rarely.

How is continuous commissioning different from retro-commissioning?

Retro-commissioning is a project with a start and an end, typically repeated every three to five years. Continuous commissioning, also called monitoring-based commissioning, uses permanent metering, trend data, and analysis software to keep the investigation running after the project closes, so drift is found and corrected between studies. Lawrence Berkeley National Laboratory expects savings from monitoring-based commissioning to be more robust and persistent than savings from conventional commissioning.

Do retro-commissioning savings last?

Partly. A Lawrence Berkeley National Laboratory study of eight retro-commissioned buildings found whole-building electricity savings of about 10.5 percent in the second year, falling to about 8 percent in the fourth. The causes identified included operators changing setpoints after occupant complaints, sensor calibration drift, and control settings recorded only on paper or in an operator's memory.

Which buildings benefit most from retro-commissioning?

Buildings with a building management system, energy use above their peers in benchmarking, frequent comfort complaints, or a history of tenant and space-use changes since anyone last reviewed the controls. Large buildings with complex HVAC systems tend to produce the most findings, because they carry the most schedules, setpoints, and sequences that can drift.

Who is qualified to perform retro-commissioning?

Independent commissioning firms, engineering consultancies, and controls contractors all perform retro-commissioning. Recognized individual credentials include the Certified Commissioning Authority (CxA) from the AABC Commissioning Group, the Building Commissioning Professional (BCxP) from ASHRAE, and the Certified Building Commissioning Professional (CBCP) from the Association of Energy Engineers. Mandates such as Seattle's Building Tune-Ups set their own qualification rules.

Is retro-commissioning required by law?

In some jurisdictions. As of 2026, New York City's Local Law 87 requires an energy audit and retro-commissioning every ten years for buildings over 50,000 gross square feet. Los Angeles requires an audit and retro-commissioning every five years for privately owned buildings of 20,000 square feet or more, and Seattle and Philadelphia require building tune-ups, a closely related process, every five years for non-residential buildings of 50,000 square feet or more. Some building performance standards, such as Oregon's, also require an energy audit and cost-effective efficiency measures from buildings that miss their energy use intensity targets.

How does building re-tuning differ from retro-commissioning?

Re-tuning is a scaled-down form of retro-commissioning developed by Pacific Northwest National Laboratory, focused on building automation system controls that operators can adjust at little or no cost. In a 2017 review of 26 federal office buildings and courthouses, re-tuning averaged 12.1 percent annual energy savings.

Does retro-commissioning need trend data from the building management system?

Trend data makes the investigation faster and more thorough, because a provider can see weeks of operation across many conditions instead of a single site visit. Where the building management system does not trend a needed point, providers install short-term data loggers. Buildings with good trend histories usually need less logging and less on-site time.

How does ASHRAE Guideline 36 relate to retro-commissioning?

ANSI/ASHRAE Guideline 36-2024 documents high-performance sequences of operation for common HVAC systems. Retro-commissioning frequently finds sequences that never matched design intent or were rewritten during troubleshooting, and Guideline 36 gives owners and providers a published reference when they correct or replace those sequences.

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Energy

Retro-Commissioning: A Complete Guide

Published Oct 30, 2026

In short

Retro-commissioning is a systematic process for improving how an existing building's equipment and controls operate. A commissioning provider investigates how systems run today, tests them against the owner's current requirements, and corrects the schedules, setpoints, control sequences, and sensors that have drifted, usually at low cost and without replacing equipment.

Retro-commissioning, also written retrocommissioning or retro commissioning and abbreviated RCx, is the established method for finding and correcting the operational drift that builds up in existing buildings. Over the years, tenants move, spaces are repurposed, controls contractors change, and operators adjust setpoints to answer comfort complaints. Each change is small and reasonable when someone makes it. Together the changes leave a building running to a set of requirements nobody wrote down.

Retro-commissioning sits between routine maintenance, which keeps equipment running, and retrofits, which replace equipment. The ENERGY STAR Building Upgrade Manual cites a December 2004 study by Lawrence Berkeley National Laboratory, Portland Energy Conservation Inc., and the Energy Systems Laboratory at Texas A&M University, which concluded that retro-commissioning is one of the most cost-effective means of improving energy efficiency in commercial buildings.

How is retro-commissioning different from commissioning?

Commissioning, retro-commissioning, recommissioning, and ongoing commissioning apply the same quality-assurance process at different points in a building's life. Each verifies that systems operate to a documented set of owner requirements. The variants differ in when the process happens and how long it runs.

Commissioning (Cx): Applies to new construction and to new systems installed in existing buildings. The commissioning provider verifies that systems are designed, installed, tested, and capable of being operated to the owner's project requirements before handover. ANSI/ASHRAE/IES Standard 202 sets out the normative process.

Retro-commissioning (RCx): In the words of the ENERGY STAR Building Upgrade Manual (revised October 2007), "the same systematic process applied to existing buildings that have never been commissioned." The baseline is how the building is used today, which frequently differs from the use its designers planned for.

Recommissioning: The process repeated on a building that was commissioned or retro-commissioned before. The same manual says recommissioning "is normally done every three to five years."

Continuous or monitoring-based commissioning (CCx or MBCx): Permanent metering, trend collection, and analysis software keep the investigation running after the initial project closes, so systems are retuned as drift appears between scheduled studies. Texas A&M University's Energy Systems Laboratory developed the Continuous Commissioning process in the early 1990s, and Continuous Commissioning® remains a registered trademark of the Texas A&M Engineering Experiment Station. In lowercase, the term is used more broadly for any ongoing, data-driven commissioning practice.

Type	Building	Timing	Typical trigger
Commissioning	New construction or new systems	Once, before handover	Project delivery, code or certification requirement
Retro-commissioning	Existing, never commissioned	Once, as a project	High energy use, comfort complaints, a mandate
Recommissioning	Existing, previously commissioned	Periodic, often every three to five years	Scheduled cycle, renewed mandate, change of use
Continuous or monitoring-based commissioning	Existing	Continuous	Holding savings between studies

The terms blur in practice. Many owners, providers, and regulations use retro-commissioning for any commissioning of an existing building, and New York City's Local Law 87 uses the term for the requirement it places on every covered building.

How does the retro-commissioning process work?

A retro-commissioning project moves from planning through investigation, implementation, and verification. ASHRAE Guideline 0.2-2015, the commissioning guideline for existing buildings, describes the stages as planning, assessing, investigating, implementing, verifying, and documenting performance. Practitioners commonly group them into the following stages.

Planning: The owner benchmarks the building's energy use, usually in ENERGY STAR Portfolio Manager, and selects a provider. The provider gathers mechanical drawings, sequences of operation, point lists, and maintenance records, interviews operators, and documents what the building needs to do today. Guideline 0.2 calls that document the Current Facility Requirements. The owner and provider set the scope at this stage, including which systems are covered and how much functional testing the budget allows.

Investigation: The provider walks the building, reviews trend data from the building management system, and installs short-term data loggers where a needed point is not trended. Functional tests drive equipment through its operating modes to see whether the equipment responds as its sequence requires. The output is a findings list in which each item carries an estimated energy and cost impact and an estimated cost to correct.

Implementation: The owner selects which findings to implement. In-house operators or a controls contractor make the corrections, most of which are programming changes in the building management system rather than physical work.

Verification and hand-off: The provider re-tests corrected equipment, measures savings against the pre-project baseline, updates the systems documentation, and trains operators on what changed and why. The ENERGY STAR manual warns: "Without training for facility staff and an operations and maintenance program, the benefits that accrue will not last."

Which problems does retro-commissioning find?

Retro-commissioning findings are typically operational: equipment that works but runs at the wrong time, to the wrong setpoint, or against other equipment. The ENERGY STAR manual reports that in a study of retro-commissioned buildings, problems "related to the overall HVAC system were the most common type."

Category	Typical findings
Schedules	Equipment running through unoccupied hours, holiday schedules missing, temporary overrides left in place
Setpoints and resets	Supply air and chilled water resets disabled, setpoints drifted from design, deadbands narrowed after complaints
Economizers	Dampers stuck or disconnected, high-limit lockout set incorrectly, minimum outdoor air set above requirement
Simultaneous heating and cooling	Reheat running against cooling, or heating and cooling valves leaking through
Sensors	Temperature sensors drifted out of calibration, failed humidity or CO2 sensors, sensors in unrepresentative locations
Sequences of operation	Sequences that never matched design intent, or were rewritten during troubleshooting and never restored

Where a building's sequences have to be rewritten, providers increasingly work from ANSI/ASHRAE Guideline 36-2024, which documents high-performance sequences of operation for common HVAC systems.

Most of these findings cost little to correct, because the fix is typically a change in the building automation system. Pacific Northwest National Laboratory's re-tuning approach, a scaled-down form of retro-commissioning focused on building automation system controls, averaged 12.1 percent annual energy savings across 26 federal office buildings and courthouses in a 2017 review, even though those buildings started from very efficient baselines. A spring recommissioning checklist works through the seasonal version of these checks.

How much does retro-commissioning cost, and how much does it save?

Half of the existing-building commissioning projects in Lawrence Berkeley National Laboratory's database paid back within 1.7 years. The laboratory's 2020 update of the database, compiled with the Building Commissioning Association, covers 1,482 buildings across three decades and reports the following for existing buildings.

Measure	Existing buildings
Median cost per square foot, 2018 sample	$0.26, down 33 percent from the 2009 sample
Median simple payback	1.7 years, with a 25th to 75th percentile range of 0.8 to 3.5 years
Median primary energy savings, utility program projects	5 percent
Median primary energy savings, monitoring-based commissioning in utility programs	9 percent
Median primary energy savings, projects outside utility programs	14 percent

Earlier editions of the database reported higher savings. The 2009 assessment, led by Evan Mills, compiled 643 buildings totaling about 100 million square feet across 26 states, identified more than 10,000 energy-related problems, and reported median whole-building savings of 16 percent at $0.30 per square foot, with a 1.1-year payback, for existing buildings. The 2004 edition, covering 224 buildings, reported 15 percent savings at $0.27 per square foot and a 0.7-year payback, as cited in the ENERGY STAR Building Upgrade Manual.

The figures are medians from projects that reported results, a sample likely to skew toward successful projects. Savings also depend heavily on how many of the recommended measures the owner implements, which varies widely from project to project.

Why do retro-commissioning savings fade?

Retro-commissioning savings decay because the conditions that produced the original drift are still in place after the provider leaves. Operators still answer comfort complaints by adjusting setpoints, sensors still drift, and the record of what was changed often lives in a binder or in one operator's memory.

The most cited evidence comes from a Lawrence Berkeley National Laboratory study of savings persistence at eight buildings in the Sacramento Municipal Utility District's retro-commissioning program, by Norman Bourassa, Mary Ann Piette, and Naoya Motegi. Whole-building electricity savings were about 10.5 percent in the second year after retro-commissioning and about 8 percent in the fourth. Owners implemented 59 percent of the recommended measures, and 81 percent of the implemented measures were still in place at the recommended settings. The four measures abandoned outright were all air distribution controls. The authors also cite a Texas A&M study of 10 buildings that found about 80 percent of savings remaining three to four years after commissioning.

The paper identifies the following causes of decline:

Operators changing setpoints in response to occupant calls
Calibration drift in sensors and components
Control settings that are hard to access, with paper records or an operator's memory as the only record
Operators receiving no feedback on how their changes affect energy use

Lawrence Berkeley National Laboratory's 2009 assessment found that savings "tend to persist well over at least a 3- to 5-year timeframe" and noted that data over longer horizons are not available. Owners typically respond to the persistence problem with periodic recommissioning, continuous monitoring, or both.

How does continuous commissioning relate to fault detection?

Continuous commissioning turns the investigation phase of retro-commissioning into a permanent function. Permanent meters and trend logs feed analysis software, which flags equipment that departs from its intended operation without waiting for the next study.

Lawrence Berkeley National Laboratory's monitoring-based commissioning study of 24 projects in University of California and California State University buildings found median electricity savings of 9 percent, a median cost of $1.00 per square foot, and a median simple payback of 2.5 years. The study concluded that savings "are expected to be more robust and persistent for MBCx projects than for conventionally commissioned ones."

Fault detection and diagnostics (FDD) software does most of the analysis in continuous commissioning. An FDD rule encodes the same kind of check a retro-commissioning provider makes by hand, such as an economizer that should be in free cooling or a valve that should be closed, and runs that check against every trend sample. The fault detection and diagnostics guide covers how those rules work.

Continuous detection changes the workload as well as the timing. A retro-commissioning study delivers one ranked findings list per cycle, while FDD produces findings every day: Lawrence Berkeley National Laboratory's fault prevalence research counted about 245 faults per building per month across 317 buildings. Drift shows up in the data soon after it starts, and the limiting factor becomes the engineering time needed to investigate and correct each fault.

Which laws require retro-commissioning?

As of 2026, a small number of US cities mandate retro-commissioning or a closely related tune-up, and some building performance standards require an energy audit and efficiency measures from buildings that miss their targets.

New York City, Local Law 87: Buildings over 50,000 gross square feet, and tax lots or condominium groups whose buildings together exceed 100,000 gross square feet, must complete an energy audit and retro-commissioning every ten years. The Energy Efficiency Report is due in the year whose last digit matches the last digit of the building's tax block number, and a registered design professional must file the report.

Seattle, Building Tune-Ups: Buildings with 50,000 square feet or more of nonresidential space, excluding parking, complete a tune-up every five years. A qualified Tune-Up Specialist assesses building systems and operations, the owner corrects the problems found, and the specialist verifies the changes before the report goes to the city.

Philadelphia, Building Energy Performance Program: Non-residential buildings with at least 50,000 square feet of indoor floor space complete a tune-up, certify as high-performance, or receive an exemption, repeating the process every five years.

Los Angeles, Existing Buildings Energy and Water Efficiency program: Privately owned buildings of 20,000 square feet or more complete an energy and water audit and retro-commissioning every five years, unless they qualify for one of the program's exemptions.

Building performance standards take a different route to the same work. Oregon's Building Performance Standard, for example, requires Tier 1 buildings that do not expect to meet their energy use intensity target to complete an energy audit and life cycle cost assessment, then implement cost-effective efficiency measures.

Building performance standards that cap energy use or emissions, including New York City's Local Law 97, Boston's BERDO, and Washington's Clean Buildings Performance Standard, do not mandate retro-commissioning. Retro-commissioning is nonetheless a common early measure for owners working toward those targets. The building energy regulations guide maps those laws by jurisdiction, with coverage thresholds and deadlines.

Who performs retro-commissioning?

Independent commissioning firms, mechanical engineering consultancies, and controls contractors perform most retro-commissioning, and trained in-house operators often carry out the lighter-weight re-tuning variant. Many owners prefer a provider independent of the contractor who will implement the corrections, which separates the party identifying problems from the party paid to fix them.

Individual credentials recognized in the field include the following:

Certified Commissioning Authority (CxA): Issued by the AABC Commissioning Group
Building Commissioning Professional (BCxP): Issued by ASHRAE
Certified Building Commissioning Professional (CBCP): Issued by the Association of Energy Engineers

Mandates can set their own qualifications. Seattle requires a Tune-Up Specialist with at least seven years of educational or professional experience, completion of the city's Tune-Up Specialist training, and one of a list of certifications that includes the CxA and a Professional Engineer license in mechanical or architectural engineering.

Standards and guidelines

ASHRAE publishes the main reference documents for commissioning in North America and lists the current edition of each in its catalog of titles, purposes, and scopes.

Document	Scope
ASHRAE Guideline 0-2019	The commissioning process for whole buildings, across all phases and disciplines
ANSI/ASHRAE/IES Standard 202-2024	The normative commissioning process for new buildings and new systems, written for adoption into contracts and codes
ASHRAE Guideline 0.2-2015	The commissioning process for existing building systems and assemblies
ASHRAE Guideline 1.1-2025	Technical requirements for commissioning HVAC&R systems
ASHRAE Guideline 1.2-2019	Technical requirements for commissioning existing HVAC&R systems
ANSI/ASHRAE Guideline 36-2024	High-performance sequences of operation for HVAC systems
ASHRAE Guideline 14-2023	Measurement of energy, demand, and water savings

The International Performance Measurement and Verification Protocol (IPMVP) is the other common reference for verifying savings after implementation.

How should an owner evaluate a retro-commissioning provider?

A retro-commissioning study is only as useful as the findings an owner can act on and keep in place. The following criteria apply to any provider.

Use of trend data: Whether the provider analyzes building management system trends across several weeks and operating conditions, or relies mainly on a site walk-through.

Functional testing depth: Which equipment classes the provider will test, and in which modes.

Findings format: Whether each finding carries a probable cause, an estimated energy and cost impact, and an estimated cost to correct, so the owner can rank the findings.

Implementation support: Whether the provider works alongside operators or the controls contractor during corrections, or hands over a report at the end of the investigation.

Measurement and verification: How the provider will measure savings, against which baseline, and at which level, from the whole-building meter down to individual systems.

Persistence plan: Which trends, alarms, or checks will tell the owner that a corrected setting has reverted, and who is responsible for watching those signals.

Where Noda fits

Noda is an agentic AI platform for commercial building operations that works as an always-on virtual building engineer, scaling engineering team capacity across every asset in a portfolio.

Retro-commissioning studies correct the drift present at the time of the investigation, and the causes of decline identified in the Sacramento research, from setpoint changes after occupant calls to sensor drift, resume once providers leave. Noda performs continuous commissioning, keeping the investigation running between studies across every connected building.

Each site connects through a Noda LaunchPad, an on-premise gateway that reads the building management system over open protocols such as BACnet/IP and Modbus, without replacing the BMS. Noda maps the BMS points to a standard equipment model, then analyzes trend data, meter data, and weather continuously and traces faults to their root causes, frequently on upstream equipment such as the air handler serving a group of terminal units. Noda tests each finding against historical data from several points before raising it, and each confirmed issue becomes a proposed change to a setpoint, schedule, or control sequence, with the evidence and an estimate of the annual savings, for an engineer to accept or decline.

Where Noda's fault detection rules cover the condition, a setpoint reverted after a comfort call or an override left in place appears as a new finding well before the next study cycle. Noda also tracks the savings each completed change returns, giving operators the feedback on energy use that the Sacramento study found missing. Functional testing and on-site investigation by a commissioning provider remain part of a complete retro-commissioning program. The Intelligence Layer page describes the approach in more detail.

Frequently asked questions

Is retro-commissioning the same as an energy audit?
No. An energy audit identifies efficiency measures across a building, including equipment replacements and other capital upgrades. Retro-commissioning concentrates on how existing equipment and controls operate, uses functional testing and trend data to find problems, and carries the corrections through implementation and verification. New York City's Local Law 87 requires both, which is why owners there often procure the two together.
How often should a building be recommissioned?
The ENERGY STAR Building Upgrade Manual says recommissioning is normally done every three to five years, and sooner when energy use rises or comfort complaints increase. Laws that mandate the process set their own cycles: every five years under Seattle's Building Tune-Ups and Philadelphia's Building Energy Performance Program, and every ten years under New York City's Local Law 87.
How much does retro-commissioning cost?
Lawrence Berkeley National Laboratory's 2020 update of its commissioning database found a median cost of $0.26 per square foot for existing-building commissioning in its 2018 sample, 33 percent lower than in its 2009 sample. Cost varies with building size, system complexity, and how much trend data is already available.
How much energy does retro-commissioning save?
Lawrence Berkeley National Laboratory's 2020 analysis of commissioning in existing buildings found median primary energy savings of 5 percent for projects in utility programs, 9 percent for monitoring-based commissioning in utility programs, and 14 percent for projects outside utility programs, with a median simple payback of 1.7 years. Individual results vary widely with the building's starting condition and with how many of the recommended measures the owner implements.
Does retro-commissioning require new equipment?
Rarely. Most findings are corrected in the building management system: a schedule, a setpoint, a reset strategy, or a control sequence. Some findings require repairs, such as replacing a failed damper actuator or a drifted sensor. Equipment replacement falls outside the usual scope, and owners handle it as a separate retrofit project.
How does functional testing work in retro-commissioning?
A functional test drives a piece of equipment through its operating modes and records whether the equipment responds as its sequence of operation requires. A provider might command an air handler from occupied to unoccupied mode, or force an economizer into free cooling, and observe dampers, valves, and temperatures. Functional testing finds problems that trend data alone cannot show, because some operating modes occur rarely.
Is recommissioning different from retro-commissioning?
The process is the same. Retro-commissioning applies to a building that was never commissioned, while recommissioning repeats the process on a building that was commissioned or retro-commissioned before. In practice, many owners, providers, and regulations use retro-commissioning for any commissioning of an existing building.
How is continuous commissioning different from retro-commissioning?
Retro-commissioning is a project with a start and an end, typically repeated every three to five years. Continuous commissioning, also called monitoring-based commissioning, uses permanent metering, trend data, and analysis software to keep the investigation running after the project closes, so drift is found and corrected between studies. Lawrence Berkeley National Laboratory expects savings from monitoring-based commissioning to be more robust and persistent than savings from conventional commissioning.
Do retro-commissioning savings last?
Partly. A Lawrence Berkeley National Laboratory study of eight retro-commissioned buildings found whole-building electricity savings of about 10.5 percent in the second year, falling to about 8 percent in the fourth. The causes identified included operators changing setpoints after occupant complaints, sensor calibration drift, and control settings recorded only on paper or in an operator's memory.
Which buildings benefit most from retro-commissioning?
Buildings with a building management system, energy use above their peers in benchmarking, frequent comfort complaints, or a history of tenant and space-use changes since anyone last reviewed the controls. Large buildings with complex HVAC systems tend to produce the most findings, because they carry the most schedules, setpoints, and sequences that can drift.
Who is qualified to perform retro-commissioning?
Independent commissioning firms, engineering consultancies, and controls contractors all perform retro-commissioning. Recognized individual credentials include the Certified Commissioning Authority (CxA) from the AABC Commissioning Group, the Building Commissioning Professional (BCxP) from ASHRAE, and the Certified Building Commissioning Professional (CBCP) from the Association of Energy Engineers. Mandates such as Seattle's Building Tune-Ups set their own qualification rules.
Is retro-commissioning required by law?
In some jurisdictions. As of 2026, New York City's Local Law 87 requires an energy audit and retro-commissioning every ten years for buildings over 50,000 gross square feet. Los Angeles requires an audit and retro-commissioning every five years for privately owned buildings of 20,000 square feet or more, and Seattle and Philadelphia require building tune-ups, a closely related process, every five years for non-residential buildings of 50,000 square feet or more. Some building performance standards, such as Oregon's, also require an energy audit and cost-effective efficiency measures from buildings that miss their energy use intensity targets.
How does building re-tuning differ from retro-commissioning?
Re-tuning is a scaled-down form of retro-commissioning developed by Pacific Northwest National Laboratory, focused on building automation system controls that operators can adjust at little or no cost. In a 2017 review of 26 federal office buildings and courthouses, re-tuning averaged 12.1 percent annual energy savings.
Does retro-commissioning need trend data from the building management system?
Trend data makes the investigation faster and more thorough, because a provider can see weeks of operation across many conditions instead of a single site visit. Where the building management system does not trend a needed point, providers install short-term data loggers. Buildings with good trend histories usually need less logging and less on-site time.
How does ASHRAE Guideline 36 relate to retro-commissioning?
ANSI/ASHRAE Guideline 36-2024 documents high-performance sequences of operation for common HVAC systems. Retro-commissioning frequently finds sequences that never matched design intent or were rewritten during troubleshooting, and Guideline 36 gives owners and providers a published reference when they correct or replace those sequences.
How are retro-commissioning savings measured?
Retro-commissioning savings are measured by comparing energy use after implementation against a baseline from before, adjusted for weather and occupancy. ASHRAE Guideline 14 and the International Performance Measurement and Verification Protocol (IPMVP) are the standard references. Measurement at the whole-building meter suits large savings, while smaller measures are verified at the system or equipment level.