May 2006

Innovations in Comfort, Efficiency, and Safety Solutions.

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  Thomas Hartman, P E
The Hartman Company

Contributing Editor

A Three Part Series

Be sure to read Tom's May interview on this topic
What’s Relational Control?

PART 1: Why PID Control is Outdated for Modern Building Applications

PART 2: An Introduction to Relational Control

The first two parts of this series discussed employing relational control to replace outdated PID control and achieve improved system performance. When I explain relational control to other engineers, a question I am often asked is: “Why hasn’t anyone thought of this before?” In fact a number of people have been receptive to new methods of control as I have found from the substantial correspondence this and other of my recent articles on emerging control theory and techniques have generated. But those of us that work with new approaches find we are constrained from moving forward with them by the way projects in this industry are organized and managed. The question we need to ask ourselves is “What is it that constrains us from successfully applying more effective advanced control technologies and how can we overcome those constraints?”

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Relational control provides a whole new theoretical and practical structure for designing and operating HVAC systems. With relational control, systems can perform far more effectively and efficiently than has been possible with PID based controls. But the concerns that enlightened designers and manufacturers have about employing such new control techniques are genuine and need to be addressed. Most of us who work with efficiency and performance focused projects know that a great many such projects do not live up to their performance expectations. We also know that the fault rarely lies in the applied technologies, but rather in the process by which they are applied. I think there is reasonably wide agreement within the industry that the process our industry uses to implement HVAC systems is a primary contributing factor to the difficulty we have in obtaining truly high performing systems. Something is certainly missing in that process that makes it difficult to succeed with above standard performance objectives.


I believe there are two fundamental missing or defective elements in the current practice of the HVAC design and implementation process. The industry has danced around them for the last several decades, but never really resolved them in any meaningful way. The first is a lack of continuity. In many projects the design team is not well connected into the remainder of the process so that "design intent," if it ever is well established in the design stage, is likely to be thoroughly diluted or lost through subsequent project stages. I use the term "over the fence" to describe the transfer of intent from one stage to another. The designer throws the design over the fence to the contractor, and the contractor does the same to the operations staff. If there's a commissioning agent, intent often transfers in and out of that stage the same way. It's a process that can only work in a relatively static industry - when design and installations are essentially the same time after time and everyone has a good understanding of what the intent of each element is. But this process works poorly in today’s more complex projects, and it often is disastrous when this disconnected process is employed to apply advanced integrated technologies.

The second element that is lacking is performance assurance. We continue to see severely underperforming systems in conventional as well as high performance buildings. Most projects today aim for much more than just heating and cooling. Owners expect their projects to deliver the required system output with improved performance (efficiency) and improved end results (comfort). High performance is a "product" the HVAC industry is increasingly asked to deliver. We need to develop a responsibility path to ensure that product is delivered, and to do so we need to incorporate some method within the organization and scope of each project process to delegate the authority, responsibility and means of accounting in order to ensure it is delivered. Our industry has operated so long without such an accountability path that it seems to have lost its commitment to actually deliver performance. Many do not even know how well their last project is performing. They just know whether or not it has been accepted.

These two deficiencies are related and the solution to both revolves around adjusting the HVAC project process so that these missing elements are reincorporated effectively. Unfortunately, many of the steps that have become popular for high performance buildings and systems involve adding more players and/or more steps into this same weak process. Bringing new ideas and expertise to a project can help, but the way this is often accomplished today further diffuses responsibility and works counter to the goals of improving continuity and assuring performance. We as an industry need to do much better in the process of integrating continuity and responsibility into 21st  Century projects!


Relational Control is certainly an important link to a higher performing future for the HVAC industry, but applying such a new technology with this weak process will almost certainly not obtain the desired results and could, as stated earlier, even further weaken the process with potentially disastrous results. So how should we proceed?

No one entity can answer this question. Rather, all in the industry need to contribute to this answer if we are to be successful in obtaining the performance promised by relational control. I’d like here to offer several steps that I think are important for each of us to take to help our industry work its way toward the answer.

STEP 1 – Recognize the problem: I’m amazed how often I find colleagues that work in engineering offices or for manufacturers or contractors seemingly oblivious to the energy and comfort problems that plague our industry. Certainly no one likes to broadcast failure, but the fact that comfort and indoor environmental quality continue to top the list of complaints that occupants have about their workplaces, and the well documented underperformance of many designs originally focused on energy efficiency should act as a wake up call that we as an industry are not doing well. We need to own up to this and commit ourselves to doing much better. This step is essential if we are to move forward.

STEP 2 – Prepare for change: In the many discussions I have had on industry transformation, I find it interesting that nearly everyone accepts the fact that change would be good for the industry, but almost none of these individuals thinks the change should involve them. Rather, the feeling seems to be that someone else needs to change. All of us in the industry need to realize that to be effective, change needs to be universal. We all need to be ready and willing to accept change in our daily professional activities.

STEP 3 – Focus on the client: A few years ago I read an article about telecommunication firms that successfully navigated the infusion of new technologies into that industry. The author’s conclusion was that those that were most successful were the ones that focused their efforts on “doing the right thing” while those who followed conventional business advice and worked hard to protect their markets through the changing times appeared to be much less successful. That lesson should be taken by all in this industry. If we focus our efforts on doing what is best for our end use clients, we are much more likely to succeed through the changing times ahead.

STEP 4 – Institutionalize success and discard failure: Everyone likely agrees with this idea but many firms in our industry have lost the important link to the end user so we often never find out which elements of our products or services are successful and which are not. We all need to restore that link and work to improve our weaknesses and hold onto our strengths. 

STEP 5 – Work together and try new approaches: For some time now a developing trend in our industry has been a new flexibility in assembling teams to design and construct HVAC systems more cost effectively. Success continues to be elusive because the team members must first resolve these prerequisite steps, but I am confident that as we begin to get a greater understanding of the prerequisites, vehicles for new approaches to working together for implementing advanced technology systems more successfully will be readily available. We need to be sure to encourage and join teams employing such new approaches whenever possible.


In this series, I have tried to demonstrate that there is a great opportunity for advancement in the state of the art of HVAC system configuration and control technologies. With these new relational control technologies now available, I am confident that our industry can play an important role in resolving the energy and environmental issues that are becoming critical today and are likely to grow and continue to impact society over the next several generations. But to play our role successfully, we need to commit ourselves to a new vision of our industry and the role of each of us in it. This is not easy, but it certainly is possible as other industries have already experienced the revolution we are facing and become strengthened through it all. Now it’s time for ours. Are we ready?


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