Retro-Commissioning

As the increasing number of new buildings set a high energy performance standard, building owners are looking to upgrade their existing portfolio to reap the benefits of lower utility bills and improved occupant comfort. The challenge is figuring out where to begin: what retrofits or operational changes will yield the greatest result? The one service that provides the greatest bang for your buck when it comes to existing buildings is retro-commissioning.

Commissioning” is a quality assurance program that delivers a new building, functioning as the owner intended, and delivering the energy performance expected. A commissioning agent will examine the systems and controls of a building to ensure proper installation, programming, operation, and performance. “Retro-commissioning” is the same, except it is conducted on an existing building that has never been commissioned previously (with most buildings falling under this category). “Re-commissioning” is for an existing building that was commissioned in the past. In some circles, the term re-commissioning is used to mean commissioning of older buildings, whether they have ever been previously commissioned or not.

Retro-commissioning starts when a building owner hires a commissioning agent who examines the performance of a building or a portfolio of buildings to assess energy use, operational issues, and occupant comfort complaints. (If a portfolio, the worst-performing buildings will likely be targeted for further retro-commissioning.)

The assessment is conducted by gathering utility bills, reviewing the original design intent, speaking with facility managers, and interpreting the information provided by building systems trend logs (charts explaining equipment operation and building conditions at particular times).

The retro-commissioning agent will provide no-, low-, and costly options to the owner in the form of a report, which also outlines the payback expected from each update. The owner can then decide which changes to undertake.

A Tenanted Office Case Study

Enermodal’s Commissioning Division recently completed commissioning on an existing office building in southwestern Ontario. The owner realized something was wrong when the building’s energy bills were much higher than expected.

After calling in the agent, it was discovered that the mechanical system was quite complex and the controls contractor did not understand the system, as the control sequences were improperly programmed. For example, the building system was reclaiming heat from one location as intended, but rather than reusing that heat elsewhere to save energy, the controls had that heat sent to a cooling tower and into the outdoors — in other words, wasted. A no-cost solution provided by the commissioning agent was to reprogram the software to correct this issue, resulting in $60,000 a year in energy savings for the owner (approximately double the original cost of the commissioning agent).

In terms of occupant complaints, several people found their offices too cold. The commissioning agent discovered that the thermostats were installed in an area of the wall that was in direct sunlight for much of the day. Therefore, the thermostat thought the room was warmer than it actually was and did not provide sufficient heating. The agent provided a low-cost solution of recommending new locations for the thermostats.

Be sure to ask…

Building owners hiring a retro-commissioning agent should ensure the agent plans to provide the following services:

• Ensure controls are installed and/or set to allow for the proper amounts of outdoor air: too little leads to poor air quality, but not enough is an energy waste. Depending on the problem, improper ventilation can be corrected with balancing, new control sequences, or the installation of certain equipment.

• Evaluate the building envelope to ensure there are no leaks, which can be caused by issues such as improperly installed windows or not enough insulation. An infrared scan and tenant complaints are excellent ways of spotting envelope problems.

• Examine existing equipment replacement plans on file with the facility or operations manager to ensure the plan is properly adjusted after retro-commissioning work is complete. The commissioning report may recommend some equipment be replaced immediately or a piece of equipment previously destined for imminent replacement can be kept for many more years.

• Train maintenance staff on how to properly run the equipment given the changes implemented by the commissioning agent. The agent should provide a detailed operations manual and on-site training, including an intensive “building and controls walk through.”

Many building owners do not take on a retro-commissioning agent due to cost or because they do not understand the benefits. But unlike many existing building retrofits, retro-commissioning has a very quick payback, usually one to five years. Plus, the improvements to occupant comfort and resulting reduction in maintenance costs are not included in the payback. Ultimately, compared to the cost of energy and maintenance, investing in making sure the building is performing at the highest possible level only makes sense. B

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