True Analytics™ - Energy Savings, Comfort, and Operational Efficiency
Hartman, P E
The Hartman Company
Now, with the growing use of building networks and the convergence of building controls and IT networks, it is becoming far easier to connect building occupants to the building control system by employing a simple "comfort and lighting" icon on each occupant's PC.
I have had many recent conversations with colleagues who are rightly excited about the changes taking place within the building controls industry. But after listening to many of the views expressed as to what these changes will bring, I find myself increasingly anxious because it seems to me that the real possibilities and opportunities of the current move toward integrating controls into standard information technology (IT) platforms are not yet on the radar screen for many in our industry - even some that are strong promoters of network controls and the inevitable convergence of our industry with the wider Internet and IT industry. And unless we understand and begin moving to exploit these opportunities, it is uncertain that they ever will be fully realized.
From my longstanding involvement in the building controls industry, the Web Browser operational interfaces and benefits from integrated data management/processing are minor in comparison to the opportunities now developing from the increasing focus on standards and network integration. These developments are opening the door for two enormously important opportunities for our industry - first, integrated networks offer the opportunity for a whole new approach to making building occupants far more comfortable than can now be expected; and second, integrated network control promises quite literally to cut HVAC building energy requirements in half. This article briefly outlines the potential for these improvements that could develop - if our industry reaches a consensus on the value and importance of these opportunities and works together to exploit them as a part of the current drive toward networking and Internet controls integration.
IMPROVING BUILDING COMFORT THROUGH NETWORK CONTROL
Imagine that your company has been moved to a new building and the building manager is showing you around your new office and explaining the new state-of-the-art features that will allow you to perform at your best. You look around your office and recall that your biggest complaint about your present office is that it is frequently uncomfortable, but you don't see a temperature sensor in this one either. The building manager explains that there four offices are included in each VAV zone and each zone has only a single space temperature sensor. Yours is two offices away. However, it is explained, management feels confident that when that sensor is thermally satisfied, you'll be comfortable too.
Would you buy that argument? I don't, but it is the case made day in and day out to justify the entire purpose of our industry - all the chillers, boilers, fans, piping, ductwork, boxes and controls that make up an HVAC system. Occupant comfort is the purpose of all that equipment, but comfort control systems don't even know the temperature conditions in many occupied spaces of the buildings they are intended to maintain within comfort limits! How can anyone accept that such a system will really work?
The truth is that comfort control in buildings today is VERY crude, based on the outdated, century old concept of conditioning a building as a whole, with very little focus on individual spaces. As a result, buildings are not designed to be nearly as comfortable as they could be because individual occupant comfort is simply not the primary object of most HVAC system design efforts. There is also almost no recognition that occupants may have unique comfort preferences, and therefore there is an accompanying lack of desire to permit occupants any individual adjustment of the comfort level in their space. Instead, the industry too often blames the occupants by characterizing them as chronic complainers who will never be satisfied no matter how comfortable conditions are. This is a completely untenable situation that is long overdue for change.
For more than a decade, I have recommended that a temperature sensor be installed in every separate occupied space within any building and that a method of control be implemented that recognizes and incorporates the space temperature of all occupied spaces in the operation of the HVAC system. This approach pays off big in terms of comfort enhancement, but it can be difficult to accomplish with today's controls because building control systems currently available are not easily configured to employ more than a single temperature sensor for each terminal zone. Nor do designers or operators generally believe allowing occupants to express comfort preferences is useful, or can be effective, especially when more than a single office or workstation is served by a VAV zone. But all of this is both possible and practical. I have been closely involved for years in experimenting with, developing, and implementing control algorithms that effectively monitor the space conditions in all areas served by a VAV zone and permit occupants to register comfort preferences for these multiple office "subzones." This preference data is collected, processed and, over the network, used to regulate the operation of comfort systems with an enormously positive effect on occupant comfort.
Now, with the growing use of building networks and the convergence of building controls and IT networks, it is becoming far easier to connect building occupants to the building control system by employing a simple "comfort and lighting" icon on each occupant's PC. And it is also becoming easier to add temperature sensors and other simple individualized sensors and controls in order to provide simple and inexpensive "individual" comfort and lighting level preferences for occupants. Thus the current trends in controls networks are enabling the development of far more occupant friendly comfort controls as shown in Figure 1. These controls can be implemented with little or no cost premium (compared to conventional zone control strategies) if building controls are better designed to accommodate such features.
Keep in mind, however, that the development of occupant friendly comfort control will not be an inevitable result of the current trends in controls networks. Rather, it is up to us in the industry to push our colleagues -- designers, manufacturers, controls contractors, and even building owners -- to make better use of the trend toward networking and convergence by demanding that buildings be made more comfortable in order to correct the longstanding failure of building comfort systems to provide what is intended.
IMPROVING BUILDING EFFICIENCY THROUGH NETWORK CONTROL
While the failure of the HVAC industry to provide better comfort to building occupants is an embarrassment to our industry in the 21 century, we're doing no better when it comes to the energy efficiency of these systems. If one were to drive a car the way building comfort systems are operated, the driver would operate (modulate) the accelerator to continuously maintain the maximum engine speed required for the highest highway speed that may ever be desired. The clutch would be controlled to provide the highest torque ever needed to climb the steepest hill that might ever be encountered. Then the driver would control the speed of the car by pressing on the brake! As silly as this sounds, this is how we operate both air and hydronic systems employed for building comfort, operating them at temperatures and pressures designed to meet worst case scenarios, and then continuously "braking" the flow of air or water to every zone or load in order to obtain the desired flow. Even when setpoint optimization is added, building comfort systems remain inherently inefficient because this basic "control by braking" strategy is inherent in the building system configuration and control strategies. It has been shown that energy use for these systems can quite readily be cut in half or more by replacing these strategies with new network enabled configurations and controls that operate on the inherently more efficient "control by power," principle.
Using the "equal marginal performance principle" developed over a decade ago for directly optimizing the operation of multiple variable speed pumps and fans, a new control by power method of HVAC system control has been derived called "demand based control." This new control strategy, which can be applied to virtually every energy consuming component of an HVAC system can reduce overall HVAC electrical use for current configurations by about one-half as shown in Figure 2.
Demand based control reduces energy use by replacing control by braking that is now the centerpiece of building comfort control with a power based control strategy similar to how an automobile is actually operated. The power based control minimizes the energy wasted due to the inherent inefficiencies of these strategies. In the longer term, products and systems can be developed that eliminate the need for flow braking altogether. This will further advance the energy efficiency of modern buildings, but even now, with products that are available, the application of new network enabled demand based control will have an enormous effect on the energy performance of buildings as shown in Figure 2.
SUMMARY AND CONCLUSION
These are exciting times for the building controls industry. But they are also unsettling times for many due to their concerns that changes taking place may undercut their businesses, significantly increase competition, or make their current technologies obsolete. However, any reluctance to embrace and expand the changes taking place toward convergence of the controls industry with the IT industry is almost certainly the result of an inability to fully grasp the huge opportunities that await those who develop functional products and applications within the resulting new standards. Catering to individual comfort is not only feasible, but is becoming very economical. And catering to individual comfort has the potential to become a business in itself much as has catering to individual preferences for coffee and other amenities has become. Furthermore, the same network services required for transmitting and processing data to provide individual comfort most economically are also employed in implementing demand based control to dramatically reduce energy use. Thus a powerful one - two punch can be added to building designs; individually controlled comfort AND higher energy efficiency. These, combined with automatically billing commercial building occupants for their special comfort requests, offer an incredibly attractive business opportunity. It is quite simply a multibillion dollar business opportunity waiting to be served - if we can recognize it. So IT could be the start of something big!
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