CryogenX4 vs. Retro-Commissioning: Operations vs. Internal Condition

Key takeaways

• LBNL's study of 643 buildings found median whole-building savings of 16% from commissioning existing buildings, at a median cost of $0.30 per sq ft and a 1.1-year payback (2009 data).
• ENERGY STAR puts retro-commissioning first in its staged upgrade approach because it reveals what else needs fixing.
• RCx corrects controls, schedules, balancing and maintenance faults; it does not change the internal condition of refrigerant circuits.
• Savings from RCx can drift; ongoing commissioning and fault detection help them persist.
• Run RCx first, then treat sound compressorized equipment whose measured performance still lags.

Retro-commissioning (RCx) is a systematic process for making an existing building operate the way it should. A commissioning provider reviews documentation, tests equipment and controls, finds faults (a stuck damper, a mis-calibrated sensor, a schedule that runs the chillers all weekend) and gets them fixed. It is one of the most cost-effective energy measures with solid published data. An internal oil-fouling treatment such as CRYOGENX4 works at a different level, on the condition inside the refrigerant circuit of individual units. This page compares the two and explains why they fit together.

What retro-commissioning does

The ENERGY STAR Building Upgrade Manual defines retro-commissioning as applying the commissioning process to existing buildings that were never commissioned, so their systems can be operated and maintained to meet the owner's needs. Recommissioning repeats the process for buildings commissioned before, typically every three to five years. Ongoing commissioning leaves monitoring in place for continuous diagnostics.

ENERGY STAR places RCx first in its five-stage upgrade sequence (retro-commissioning, lighting, supplemental load reductions, air distribution, then heating and cooling) because it "provides an understanding of how a facility is operating" and helps identify which equipment needs to be replaced. Typical RCx work on HVAC includes:

• Testing, adjusting and balancing (TAB) air and water flows; ENERGY STAR estimates savings up to 10% of heating and cooling costs.
• Cleaning coils and filters; savings up to 10%.
• Calibrating sensors, fixing dampers and valves, and correcting schedules; savings up to 30% of annual heating and cooling costs.
• Chilled-water and condenser-water reset, chiller tube cleaning and water treatment, and checking compressor unloading.

The manual estimates that, taken together, RCx steps can push heating and cooling cost savings "upwards of 15 percent."

The evidence base

The best-known dataset comes from Lawrence Berkeley National Laboratory (LBNL). Evan Mills' study of 643 non-residential buildings and 99 million square feet found, for existing buildings, a median commissioning cost of $0.30 per square foot, median whole-building energy savings of 16%, and a median payback of 1.1 years. The projects uncovered more than 10,000 energy-related problems. Projects with a comprehensive approach achieved nearly twice the median savings and five times the savings of the least thorough projects. (Costs are in 2009 dollars; expect higher today.)

Savings persistence is the known weak spot: faults creep back as people override controls and sensors drift. That is why ENERGY STAR recommends periodic recommissioning, and why many owners now pair RCx with analytics. DOE's Smart Energy Analytics Campaign reported a median 9% energy savings for organizations using fault detection and diagnostic (FDD) software.

What an oil-fouling treatment does

CryogenX4 describes its product as a one-time treatment installed while the system runs. According to the company, there is no downtime, most installs take one day, no modifications are made to the system, and the work is done by trained, certified technicians. The company's description of the mechanism: compressor oil migrates past seals, circulates with the refrigerant and coats internal coil surfaces as an insulating film; CRYOGENX4's polarized molecules lift that oil and return it to the sump, condition the metal surfaces for better heat transfer, and improve the lubricity of the existing oil. CryogenX4 reports energy savings of up to 30% and a typical payback of 12 to 36 months on the treatment, and says the treatment is intended to last for the remaining life of the equipment. Results vary by equipment condition, and savings are not guaranteed.

RCx and an oil-fouling treatment overlap in one place: both care about heat-transfer surfaces. ENERGY STAR's RCx chapter calls for chiller tube cleaning and water treatment to provide "cleaner surfaces for heat transfer on both the refrigerant and water sides of the chiller tubes." Mechanical tube cleaning reaches the water side. The refrigerant side of a coil or barrel is a sealed circuit that cleaning crews do not open, which is the surface a product like CRYOGENX4 is designed to treat.

Side-by-side comparison

When to choose which

Start with RCx if the building has never been commissioned, if comfort complaints are frequent, if equipment runs when the building is empty, or if the building automation system has been patched over the years by different contractors. The LBNL data show it is hard to beat on cost-effectiveness, and you will not get trustworthy measurements of any equipment-level measure while operations are erratic.

Consider an internal treatment when operations are in good order (recently commissioned, schedules and setpoints correct, coils clean, charge verified) yet compressorized equipment still shows higher-than-expected kW per ton, long run times or poor approach temperatures. RCx findings often point straight to these units.

How to combine them

1. Retro-commission first. Fix the operational faults and record the post-RCx performance of each major unit.
2. Use the RCx data to select candidates. Units that are mechanically sound, correctly controlled, and still underperforming are the best candidates for a treatment pilot.
3. Treat and measure. Compare against the post-RCx baseline at comparable load and weather. IPMVP Option B, with metering on the treated units, suits this well.
4. Keep it tuned. Use ongoing commissioning or FDD so operational savings do not erode and hide the equipment-level result.

Many utilities offer retro-commissioning incentives; program details change frequently, so check with your utility. See custom utility rebates and M&V.

What a good RCx report should contain

• A list of every deficiency found, with location, root cause, estimated savings and estimated cost to fix.
• Which findings were implemented, by whom, and verified how (functional test results, trend screenshots).
• Updated sequences of operation and setpoint schedules that operators can keep.
• Equipment flagged for repair or replacement, with condition notes.
• A persistence plan: training, trend reviews, and the date for recommissioning.
• A measurement approach for the savings claimed, preferably consistent with IPMVP; see IPMVP options explained.

The equipment-condition notes are the bridge to the next step. If the commissioning provider found a chiller or rooftop unit that is correctly controlled but still performs poorly, that unit needs a diagnosis at the equipment level. Use diagnosing efficiency loss to separate charge, airflow, fouling and controls causes.

Where each approach runs out

RCx cannot fix what it cannot reach. A commissioning provider can correct a sequence, calibrate a sensor, or have a coil cleaned, but cannot change the internal surfaces of a sealed refrigerant circuit or the lubricity of compressor oil. An internal treatment, in turn, cannot fix a schedule that runs equipment all weekend, a stuck economizer, or a valve that is hunting. Each tool stops where the other starts.

Typical cooling-system findings in RCx

The specific faults vary, but the ENERGY STAR manual's retro-commissioning chapter lists the usual suspects on the cooling side: economizers that need repair or adjustment, dampers wired in one position or disconnected, sensors and thermostats that have drifted, operating schedules that no longer match occupancy, flows that were never balanced after renovations, and chillers or compressors that cycle because unloading controls have failed. None of these require new equipment, which is why RCx pays back so quickly when they are present. It also explains why measuring an equipment-level measure before RCx is unreliable: any of these faults can swamp the effect you are trying to see.

Next step

If your building has not been commissioned in the last three to five years, start there. If it has, pull the RCx report and list the units still flagged for high energy use or poor performance, then ask CryogenX4 about a measured pilot on those units. For a broader menu, see efficiency measures for existing buildings.

Frequently asked questions

Is retro-commissioning the same as maintenance?

No. Maintenance keeps components in working order. RCx tests whether the systems work together as intended and fixes operational faults, often finding problems routine maintenance misses.

How long do RCx savings last?

They can drift as controls are overridden and sensors age. ENERGY STAR recommends recommissioning every three to five years, and monitoring tools help savings persist.

Can I do a treatment pilot during RCx?

It is better to finish RCx first. Changing operations and equipment at the same time makes it impossible to tell which change produced which savings.

Does RCx clean the inside of refrigerant coils?

No. RCx may include coil cleaning and chiller tube cleaning on the air and water sides. The refrigerant side is a sealed circuit that is not opened during RCx.

Sources

1. Building Commissioning: A Golden Opportunity for Reducing Energy Costs and Greenhouse Gas Emissions in the United States — Lawrence Berkeley National Laboratory (E. Mills)
2. ENERGY STAR Building Upgrade Manual (2008 edition) — U.S. EPA ENERGY STAR, hosted by the Whole Building Design Guide
3. Smart Energy Analytics Campaign Reveals Continued Energy and Cost Savings for Energy Management Information Systems — U.S. Department of Energy
4. International Performance Measurement and Verification Protocol (IPMVP) — Efficiency Valuation Organization
5. Operations & Maintenance Best Practices: A Guide to Achieving Operational Efficiency, Release 3.0 — U.S. DOE Federal Energy Management Program / Pacific Northwest National Laboratory