Key Retrocommissioning Skills

For a lot of us, including myself, much of what we have come to know and rely upon as our working skill set for dealing with existing buildings has been the result of self-study and field experience (some of which can be quite sobering).  In fact, for most of the technical training I do, the students are exposed to a lot of resources and expected to do a significant amount of self-study to get up to speed on basic concepts.  This allows the actual class time can be focused on more advanced topics and on how to apply those concepts in the field.

Recently, one of the clients I do training classes for worked with me to re-organize the content we are using around a structure intended to facilitate the self learning process.  The structure we ultimately settled has its toots in an idea Barry Estes and Russ Good had come up with, which ultimately evolved to a list of ten key skills that we felt were critical “take a ways” from the class. 

For each item on the list, we were able to develop a general description of why it mattered, identify self study resources (generally, they come from the Resource List I provide on the blog opening page), and define self learning and project goals for the people attending the training.  Now that I have been working with that structure for a while, I have really come to like it, having discovered that it is a powerful organizational tool in the general case.

As a result, I thought I would share the list of skills with you and then use it to help organize the content on the blog by making a category for each skill.   Bear in mind that this list is not from any formal standard that I know of.  Rather, it is the informed opinion of the team I am working with to organize the content for a technical training class that focuses on fundamental principles and their application to the field issues encountered in retrocommissioning and ongoing commissioning projects.  

The following links will jump you to the major topics in this post.  The “Back to Contents” link at the end of each section will bring you back here.

Ten Key Retrocommissioning Skills

What follows is the list of skills I developed with Barry and Russ to organize our training content along with a brief description of why they are important.  There may be those who have a different opinion regarding these skills or who may think I have omitted something, or who maybe even disagree with what I have targeted.   If that is the case, post a comment and we can see what others think. 

Skill 01: The Ability to Benchmarking and  Perform Utility Consumption Analysis

Benchmarks are a fast way to see how your target facility compares with its peers.  Working with the utility data a bit more by normalizing it to the calendar month and looking at the average daily patterns can reveal clues regarding areas of opportunity.  And, ongoing benchmarking and utility analysis can be a good way to ensure any improvements you make persist.

Skill 02: The Ability to Scope a Facility and Identify Obvious Indicators of Opportunity

Scoping is one of the first steps in most existing building commissioning processes.   The goal is to become aware of readily identifiable indicators like noticing a throttled valve on a pump or noticing that all of the selector switches at a motor control center are in the “Hand” position.  These are clues pointing opportunities to improve performance or save resources. (pump optimization and potential scheduling respectively for the examples).  The scoping effort focuses the more in-depth analysis that will follow.

Skill 03: Have a Working Familiarity with HVAC and Other Building System Fundamental Principles

This is the broadest skill set to develop and the area where the most self study is typically required.  The classes I teach tend to be focused on HVAC and lighting and I will list the key areas my client and I targeted for self study in the next section.

Skill 04: Have a Firm Grasp of the System Concept and be able to Apply it to Develop or Mentor the Development of System Diagrams

In my experience, the system concept is critical to the design, commissioning, and operation of facilities.  Equipment needs to be considered in the context of the system it is a part of because everything interacts with everything, including systems interacting with other systems.  System diagrams area  great way to gain that perspective and document it for future use.

Skill 05: Be Familiar with the Trending Capabilities of Control Systems and Know How to Supplement Their Capabilities with Data Loggers

I am fond of saying that the building frequently knows the reason for the issues we are observing in it;  we just need to ask it what is going on.  Trends are one of the ways buildings “talk” to us.  Thus, understanding how to gather this critical information from a building is an important skill to develop.  Plus, it’s a lot of fun (in a nerdy sort of way).

Skill 06: Be Familiar with Functional Testing Techniques

Test results are another way buildings “talk” to us about their issues.   As a result, understanding how to safely structure a test and target it and the issue you are trying to understand is an important skill to develop if you are working with building systems.  And, as was the case for trending, it can be a lot of fun.

Skill 07: Be Familiar with Data Analysis Techniques

To develop answers, you need to be able to analyze the data you collect from control systems, loggers and tests.  So, learning how to use basic relationships (like the HVAC equations I link too from the opening page of the blog) and software tools like spreadsheets and manufacturer’s selection software to perform basic calculations and analysis is a critical skill to develop and one that I am always expanding myself.

Skill 08. Be Familiar With Basic HVAC and Energy Calculations

While commissioning is about performance at its core, the process is frequently used as a delivery mechanism for providing resource efficiency since systems that are performing at their peak are typically (but not always) at peak efficiency.  This skill builds from the previous one by taking your general knowledge regarding spreadsheets and other tools and learning how to use it to project resource savings using techniques like bin calculations or hour by hour calculations.

Skill 09. Be Familiar with Return On Investment (ROI) Calculations 

For most of us techie types, commissioning is a technical process and our enjoyment of it comes from the technical experience.  But as you age, you eventually realize that ultimately finances are usually the key driver behind building operations and budgets.  That means that us techies need to learn how to step outside our technical world and communicate our ideas in meaningful ways to the people managing the facilities we work in and funding the operations budgets.  Developing a basic understanding of long term financial metrics like return on investment can a very useful skill in terms of moving projects forward because you are learning to speak the language of the people controlling the budgets for your projects.

Skill 10. Develop A Competency With Control Systems

Most commissioning providers will tell you that control systems are critical elements for achieving the performance and efficiency we desire.   That means that if you want to succeed in the business, you need to develop a basic understanding of how control systems function as well as an understanding of how to go about procuring one that will meet the needs of your immediate project and the ongoing needs of your facility. This will includes having an understanding of the role point lists, narrative sequences, logic diagrams, detailed specifications, and system diagrams have in the control system procurement process.

Back to Contents

Familiarity with HVAC and Building System Fundamentals;  a “Big Nut to Crack”

For most of us, learning fundamental principles and how to apply them to our specific area of interest is where we will spend most of our self-study and and other educational efforts.  And that will probably never stop, at least it hasn’t for me.  In fact, that’s one of the things I really like about this business;  there is always something new to learn.

If you were to get into the content of the training guide Barry and Russ and I have been developing (with a lot of help from Irma Garza I might add), you would discover we touch on other areas like envelope, lighting, and day lighting, primarily in the Loads and Duct system topics (from my perspective, the building envelope is ultimately a key element in most air handling systems).  We also touch on lighting and day lighting controls under the Control System Competency topic.   So while the list is HVAC focused, its not with out regard to some other important building systems.

The point is that if you develop your own list, you may discover that you need to target other and/or add additional items for your personal self-study goals, depending on your interests and project portfolio.  Having said that, here is the list of general categories Barry, Russ, and I identified as self study targets for the our training class. 

Bear in mind that this is a class that is primarily focused on the mechanical end of things for a client that is in the Hospitality industry.  So the primary focus is HVAC and systems that are common to their facilities.   But it turns out to be a pretty good list in general for folks working on buildings on the HVAC side of things, which generally is my primary focus.

Saturated Systems

We encounter saturated systems a lot in HVAC.  For one thing, the atmosphere is a saturated system and the psych chart and the psychrometrics of moist air are how we go about understanding it.  And, the principles behind saturated systems are key to understanding refrigeration processes and steam systems.


The loads our systems serve can be complex and highly variable.  As a result, understanding the nuances of their elements and what drives them will be key to our understanding how the systems that serve them need to function.

This is actually one of the broader topics in the context of what Barry, Russ and I point the students at for our class.  In addition to understanding what the elements of a load are and how to estimate a load, we point the students at psychrometrics, lighting, day lighting and related solar loads, and envelope issues since all of those things come into play in determining the load an HVAC system will see and how it will vary over time.

Centrifugal Machines

Centrifugal machines are very common in HVAC being the technology of choice for most HVAC pumps and fans and a major technology used for the compressors in refrigeration machines.  Fortunately, if you understand the principles behind any one of the specific applications (pumps for instance, which is how I came to understand centrifugal machinery), then you can easily transfer that knowledge to the others.

Refrigeration and Cooling Equipment

Most of the things we do in buildings generate heat.  So, to keep our buildings safe, comfortable, and productive, we need to understand how refrigeration processes work and how to deliver the cooling they produce.   As a tree hugging, salmon loving Oregonian, my goal is to figure out how to do that as efficiently and sustainably as possible.

Heating Equipment

Despite the fact that the processes in our buildings typically generate heat, we often need to provide heat to offset losses at the envelope and preheat incoming air in in cold climates.   And production processes often require heat in one form or another to facilitate the fabrication of product.  As a result, understanding how to generate and deliver heat is an important thing.

Piping Systems

Pipes are everywhere in our buildings, delivering energy in one form or another, providing potable water, and removing waste.  Understanding the physics behind piping systems will be an important factor in understanding how to optimize the machinery and processes that interface with or are supported by piping networks.

Variable Flow Water Systems

Variable flow pumping allows us to match the energy we deliver to a system with the demand as it varies over time.  And, since the pressure required to deliver the flow varies as the square of the flow, variable flow plants can be powerful energy conservation strategies.  But they are tricky and if they don’t work correctly, they will waste rather than conserve energy.  As a result, understanding how they work and their nuances is an important skill to develop.

Duct Systems

Like pipes, ducts are everywhere in our buildings and the fan energy used to move air through them can be a significant factor in any building’s energy consumption profile.  That means that understanding the physics of air flow in ducts will be an important lesson to learn if you want to succeed at working in buildings, especially if you want to make them more efficient.


Economizers offer a major opportunity to save energy in our buildings by minimizing the use of mechanical refrigeration.  But, while simple in concept, they are incredibly challenging to make work, especially in climates that have a lot of variability.  And when they fail, they can waste energy in a big way.  The bottom line is that understanding them will open the door to major opportunities to save energy and make those savings persist in the buildings you are associated with.

Make-up Air and Exhaust Systems

Make-up air and exhaust systems are the embodiment of a fundamental physical principle;  conservation of mass and energy.  As Al Black, one of my mentors would often say:

The goes inta’s gotta equal the goes outas.

Because these systems handle and condition large volumes of outdoor air, they have the potential to be large energy users in our facilities.  Taking the time to understand the ramifications of conservation of mass and energy from a building science perspective will be time will spent if you work in this industry.

Variable Air Volume Systems

Variable air volume systems are one of the most common air handling approaches in use today because of their potential to save energy.  But like most energy conservation strategies, they are complex and can miss the mark if they are not well designed, tuned, and operated.  Learning how they work should be a major goal of anyone who works in this industry no matter what their specific area of expertise is.

Back to Contents

The Topics Build on Each Other

The order of topics in both of the lists above is not random.  Rather, the topics are arranged so that they build on each other.  For the Retrocommissioning Skills list, the topics generally follow the order in which most people would apply the skill as they moved through a project. 

For instance, the general steps in the process I typically use for existing building work is as follows:

  1. Get Up To Speed on the Building Prior to Visiting It:  Typically, I do this by studying the available documentation.  Utility bills are of particular interest because they can provide insight into the building’s energy use patterns and where the significant operating costs lie, especially if you compare them to drivers like occupancy, production, and the need for heating or cooling.  When combined with industry metrics regarding the savings that might be delivered by an EBCx project, they can even help define the budget for an EBCs project. As a result, I frequently use my Benchmarking and  Utility Consumption Analysis skills very early-on in a project.
  2. Make an Initial Site Visit:  Discussions with the operators and observations of the systems in action are a major focus for such a visit.  Much of the time, I am simply looking for clues that will help me understand where to target my efforts and the project budget moving forward.  The bottom line is I am using my scoping skills, my basic understanding of HVAC and Building Systems, and the System Concept very heavily at this point in the project.  I may even start to sketch up system diagrams on this visit.
  3. Gather Data Data:  Once my scoping effort has told me where I want to head, I begin to gather and analyze data.  Frequently, this involves working with trends from the control systems, deploying data loggers, developing system diagrams, and performing functional tests, all of which are on the list of key skills.
  4. Analyze Data:  Data without the insight provided by an informed analysis is not worth much.  That means that I need to work with the data I gather by employing my Data Analysis skills to identify problems and develop solutions.  Once I understand those topics, I usually use my Energy Calculation skills to try to understand the savings that might be achieved by the improvements I envision.
  5. Report to the Owner:  Often, the reporting effort is an ongoing process that is interwoven into the project as it evolves.  But in some instances, it is the final step in the investigation phase.  Either way, I need to present my recommendations framed in a context that matches the financial perspective of the Owner, in particular the person or organization who will potentially fund any improvements.  Being able to discuss things in broader financial terms than simple payback, terms like Return on Investment can be a powerful way to convey your message, especially if you embellish it with the Owner’s particular financial metrics.
  6. Implement Changes:  Many in the industry would estimate that 75% or more of the improvements we make in our commissioning processes rely on controls in one way or another.   That means that most of the time, when I am developing implementation strategies and putting them in place, I am using my Control System Competency skills.  The process is also heavily supported by my familiarity with Fundamental HVAC Principles and the System Concept.  But the reality is that the latter skills are necessary to support Control System Competency.

The order of the “fundamentals” topics is not particularly random either.  For instance, without understand the basics of  Refrigeration and Cooling Equipment, Heating Equipment, and Piping Systems, you would be hard pressed to understand how Variable Flow Water Plants operate.

Back to Contents

Hopefully, this information will provide a useful framework for you if you are trying to understand what you need to know to work in the industry or are trying to help others understand that.  Meanwhile, I will be using these categories to organize the blog content a bit more so that you can select on of them from the “Categories” drop down menu on the right side of the opening page and find supporting content and resources.

Hope everyone is having a good New Year,


David Sellers
Senior Engineer – Facility Dynamics Engineering

Click here for a recent index to previous posts

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