Traditional energy conservation measures focus on equipment replacement and small adjustments in equipment runtime. Utility compensation programs for measures like these are designed to buy-down the cost of replacement and encourage customers to make such investments. HVAC recommissioning, by contrast, focuses on inspection and reports. Yet this effort seldom succeeds like it could. That’s because inspections without performance data are substantially a waste of time. Data is needed to pinpoint problems, and, after the fact, confirm problems were fixed. Without extensive easy-to-understand data there is no way recommissioning will ever be effective.
New energy-efficient equipment has the added benefit of reducing maintenance labor and repair costs. But these reductions come at a price because energy efficient systems are more complicated, especially with exhaust heat recovery and fresh air makeup. In effect HVAC equipment simplicity has been traded for more complex equipment that also requires advanced computer-controlled.
This tradeoff in complexity means that building maintenance staff must learn how to use building automation software to track equipment performance, understand equipment operating variables and the meaning of these variables to equipment efficiency. It is no longer a matter of whether the equipment is running or not. Rather the process has become a matter of how, specifically, is it running. The days of turning on a boiler or air handler and walking away are over. The building HVAC world has morphed into computer controlled equipment that can operate more or less efficiently - it all depends. Building maintenance has moved from fix-by-replacement to fix-by-knowledge.
This new approach has left virtually all facility managers and building operators at a disadvantage. That’s because building automation systems (BAS), using computer-based controls, are designed to operate building HVAC systems and not analyze their operation. It’s not that an automation system isn’t capable of such analysis. Rather it’s that its design was based on knowing immediate equipment operating conditions and not how it is performing at the margins. After all, new systems were expected to be efficient. Why should building operators waste their time analyzing how equipment is running rather than fixing other problems? Yet why do they think new equipment is automatically efficient out-of-the-box? What about the piping and ductwork that supports this equipment? Doesn’t the equipment environment heavily influence equipment efficiency? Sure it does.
Building automation systems are used differently in buildings with more traditional HVAC equipment. Here BAS use tends to focus on finding out why there is a complaint rather than how efficient equipment operates. Older equipment tends to break more often. Sometimes breaks are easy to detect, like when a fan fails to run and space conditions are obviously incomfortable. But in most cases complaints are more subtle. Out-of-normal room temperatures may only be detectable on certain days when weather conditions require intense heating or cooling.
To solve these problems building operators need equipment operating history. In some cases space temperature history readily points to a specific equipment operating problem. But in most situations it’s not so obvious. That’s because more than one equipment variable usually impacts space environmental conditions.
Automation systems rely on building operator HVAC knowledge to understand their relationship. But wait, that’s the job of the HVAC designer and not the building operator. In effect, we ask our building operators to not only understand mechanical heat transfer but at the same time give them only casual and incomplete data from which to manage entire buildings. It doesn’t make sense.
Building environmental conditions have evolved. Studies now link space environmental conditions to student learning opportunities. Energy management used to mean turn it off. Then it became turn if off when not actually needed - usually by trimming the occupied hours. The term energy management has recently been replaced by sustainability. This implies the use of HVAC equipment only when necessary - and be sure it is used efficiently. Instead of just turn it off the philosophy is now run it more efficiently. That’s because sustainability is usually matched with indoor air quality (IAQ). It’s now understood that room environmental conditions can’t be sacrificed just to save energy. The driving consideration is outside air ventilation. The measure of outside ventilation air effectiveness is space CO2 level. Today CO2 sensors are being added to room temperature sensors acknowledging the importance of ventilation in the space.
But what’s to be done with CO2 sensors that register high levels, sometimes much higher than industry standards suggest is reasonable? Should the outside air dampers be opened? That almost never solves the problem because dampers work in conjunction with the fresh air supply, which is delivered by a duct system that may not be effectively designed, and a supply fan that doesn’t run at the right speed. The answers are not simple. A fan adjustment can help with the supply problem but what about the room units? Which ones remain starved for fresh air? For that matter, what is the relationship between supply fans and room fresh air requirements? How is it measured? And how can school management be assured they have solved this problem? The answer is in the data. In this case it’s not just a matter of CO2 levels but also a matter of heating and cooling delivered air to the space. It’s complicated, and without enough data, provided in a simple-to-understand manner, there is no assurance that these complicated equipment relationships will ever work properly.
Improving indoor air quality comes at a cost, and it’s almost always significant. Methods for introducing fresh air into classrooms are a combination art form and science project. Heat recovery air handlers reuse exhaust heat to offset warm or cold makeup air. At the same time they cool makeup air when outdoor temperatures and/or humidity are high. It’s difficult to look at a BAS screen and understand whether one or two compressors should be running to reduce humidity or outside air temperatures, all while reheating supply air using recovered heat wheel energy or boiler heat to moderate supply air conditions. Instead it’s necessary to examine captured equipment operating data, understand it in context of the type of equipment used, then evaluate equipment performance based on operating scenarios. Building automation systems are helpful but inadequate. What’s needed is a better method to visualize and capture equipment performance data and deliver unexpected operating condition messages to building managers on a continuous basis.
HVAC has morphed into equipment packed with operating variables (up to 600 alone in some heat recovery units). Instant equipment operating information is interesting but not enough. What’s needed is longer term analyses using collected data measured over all four seasons of the year. Further, collected data needs to be examined in the context of which it represents equipment operation. Reviewing a single variable is not enough. Instead multiple variables need to be considered if building operators hope to manage such equipment, instead of the equipment managing them.
Traditional building HVAC systems, some installed as long as 50 years ago, are often maintenance monsters. Building HVAC modernization is available today through financed retrofit agreements that seek to upgrade buildings for today’s energy and IAQ requirements. Building commissioning firms, working on both new and recommissioning projects, have limited time constraints. They can be there for the beginning discussions to help lead the design team. And they can be there for final system checkout to assure customers they are paying for what was specified. What they don’t do, however, is work with customers during the first year’s operation to evaluate equipment operating performance. That’s not their job. In fact, performance evaluation is entirely up to building operators using their building automation systems. But automation systems are not designed for analyzing equipment performance. The best they can do is keep track of immediate operating data. They offer little to no insight into how a building has been operating. Instead BAS equipment focuses on major equipment malfunctions - not on subtle operating conditions that actually influence energy usage.
IRIS Analytics uses open source BACnet/IP protocol for BAS data collection to periodically retrieving data. It interacts with the BAS frontend - not with individual HVAC controllers. It does not start or stop any equipment. Nor does it change system variables to improve operating conditions. This approach provides a clear delineation of responsibilities between the building automation contractor and building analytics advisory services like IRIS Analytics. Each has their respective duties. Recommended improvements are almost always available within BAS software methods. There are few reasons why analytics software should make equipment operating changes through the automation system. Control systems without BACnet (IP) can be upgraded by a local controls contractor using simple protocol converters or new automation frontends.