Retro-commissioning is the application of the commissioning process to existing buildings or systems. Building commissioning has various definitions, but the common denominator is that commissioning is a systematic process of ensuring — through measurement, testing and verification, and thorough documentation — that systems are operating in accordance with their original design intent and meet the owner's requirements.

The building's design intent can come in various forms; most notably, specifications from a design engineer or architect. Much of their design comes from building codes, standards developed by groups such as the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE), previous experience with similar projects, and information located in the design guides of HVAC equipment manufacturers. These designs are typically well thought out, whether they come from an engineer or HVAC equipment manufacturer.

In an ideal world, contractors will follow the directions set forth by whomever lays the building's design information out. The chances of meeting design intent are much greater when this is done. Unfortunately, poor attention to directions often occurs in HVAC installations, and in the servicing and maintenance of these systems as well.

From deficiencies such as units not being leveled properly, to improper installation of piping, wiring, ductwork, controls, venting, and more, the problems are numerous, and usually can be traced to not following directions. More often than not, however, as long as the system runs and provides some heating or cooling, nobody really pays any attention to it. Then, contractors come along to sell preventive maintenance plans on these underperforming non-commissioned systems, and their focus is typically equipment-based, not system-based.

Providing retro-commissioning services to your clients provides them with a plan that strategically targets optimization opportunities and helps avoid unnecessary “band-aiding” of equipment and components.

It also assists in measuring how effective a preventive maintenance program actually is (many of which we find either overdone or underdone). So many HVAC systems, units, and components are operating with deficiencies or in some fashion below design intent, that opportunities for improvement through retro-commisssioning are seemingly endless. It's a great opportunity for your company, and can provide measurable, verifiable results to your customers.

The Time is Right

In my experience, we're called upon to perform a retro-commissioning when a client is finally fed up with excessive energy consumption, excessive maintenance costs, and a lack of comfort throughout the building.

It's important, when you receive that first “help me” call from clients, that you make them aware that you don't have a magic wand. Sit down with clients and tell them that if they're going to move through a retro-commissioning process with you, it will be a partnership. It's much like patients who see a doctor: if they want to lose weight or reduce their cholesterol, they must put in some effort, too. The doctor can only do so much.

Let your retro-commissioning clients know there's a commitment on their part. They're going to have to work with you to provide information and documentation about what's going on in their building, including its history, original design intent, current usage, etc.

They must work with you to come up with a plan and help you monitor and analyze the plan, not just call you and expect that you'll save them money. They're an integral part of the process.

Tough Competition

True retro-commissioning contractors face some difficult competition from three groups.


The first group is some architectural/engineering (AE) firms. We all have friends in the AE community and I'm certainly not trying to disparage them. But some AE firms are interested in getting outside of the “standard” design realm, and retro-commissioning is where they do it. The trouble is, you can't fully and accurately assess a building without having the expertise and resources to physically comb through it and analyze how it's working. Design reviews of original blueprints and retrieving equipment nameplate data are important and necessary, but they don't tell you what's actually going on right now.


Some contractors come in with a “standard” maintenance plan for every building. But there's no way to know how effective such a maintenance program is in terms of performance metrics. To propose the right maintenance plan, you need trend log data, and the actual performance measurements that come from a true retro-commissioning.

The Naysayers

These might be design groups, or AE firms, or contractors. Their common characteristic is that they tell building owners, “We'll just change your equipment and upgrade from here to there.” However, new equipment may not solve the client's problems. It may provide a marginal energy savings, but it may not solve comfort problems or reduce overall operational costs.

A Good Place to Be

The market for retro-commissioning is strong and likely to grow. Part of the U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED®) program is LEED-EB for existing buildings, which has been expanded to spotlight operations and maintenance. Now, it's possible to earn a LEED certification for an existing building, with retro-commissioning playing a large role in the process.

I think there's going to be more of these types of opportunities available, as LEED is the gold standard for green building programs, and it ties so heavily to the retro-commissioning process. In fact, a fundamental prerequisite of the LEED-EB operations and maintenance program is that you must have a building's primary energy consuming systems retro-commissioned.

The government and the private sector have taken a big interest in green certifications, and that's good news for skilled contractors who offer thorough retro-commissioning services. Retro-commissioning allows you to provide a real plan to customers, based on a comprehensive, unbiased analysis of their building. You and the can make intelligent decisions about how to manage the critical functions of a building to ensure optimum performance, energy efficiency, and comfort.

It's a superior process that offers superior results.

Benjamin M. DiMarco is president of DiMarco & Associates, LLC, a Cleveland,OH-based commercial and residential HAVC contracting firm that provides performance-based HVAC solutions, including testing and balancing, IAQ/energy auditing, commissioning and LEED consulting services. He can be reached at 440/773-8243 or by e-mail at