Manufacturers’ tips and tricks for commissioning, balancing buildings
Two manufacturers provide insights, tools, and tips on how to commission and balance building systems.
- Jeff Abramson, Director of thermography development, Fluke Corp., Everett, Wash.
- Jessica Frackleton, Senior manager of product marketing, Onset Computer Corp., Bourne, Mass.
CSE: What engineering challenges do you help commissioning agents (CxAs) overcome?
Fluke: Test and measurement tools help commissioning agents collect accurate data that confirms a building’s performance meets the standards and specifications it was designed against. For ventilation commissioning, many agents use airflow meters, either a multipurpose air meter that incorporates outsides air, CO, and CO2, or a single-function micromanometer. At the register and for sensor checks, most CxAs use a humidity and temperature meter and some use a handheld infrared (IR) thermometer. For building controls system signal continuity verification, sometimes a CxA will use a mA or Volts dc loop tester. When inspecting the mechanical and electro-mechanical setup, a CxA will use electrical test tools to verify supply voltage and will use thermal imagers to verify appropriate performance under load. Thermal imagers are also used for building diagnostics to inspect the overall building envelope. When assessing the lighting system, a CxA will use a light meter to measure the lumens output compared to the lighting requirements for the task or activity anticipated for that area of the building.
Onset: For many of our customers, access to data from building automation systems (BAS) is either difficult to obtain, not sufficient, or non-existent. Our data loggers are a low-cost, minimally intrusive way of augmenting this data to pinpoint energy savings opportunities in both new and existing building commissioning. The access to this data allows for CxAs to really engineer solutions tailored to the usage and operational characteristics of each building they enter, thereby providing building owners and operators with true, measurable savings.
CSE: What unique challenges might engineers encounter regarding the building envelope, and how would you help overcome them?
Onset: One of the most troublesome challenges that we hear from CxAs is their inability to access data the way they want it. This problem presents itself in two critically different ways:
- Access to data is restricted because of limitations or programming requirements of the automation systems that are in place already
- The physical location of the measurement point is challenging or impossible to access.
We have helped numerous projects overcome these challenges by providing data loggers that are flexible, easy to use, and allow for data to quickly be exported to any spreadsheet program or streamed seamlessly to the Web for access anywhere. We’ve worked on many projects with our clients who desire to use a combination of loggers from our standalone to our wireless data logging networks. We often hear from customers who have a lot of success with our Web-based data logging platform because it serves as an easy-to-use, flexible data logger for collecting indoor building energy information as well as localized weather data to help normalize expected energy usage throughout the year. In many commissioning projects, the flexibility to measure what you need where you need it, and manipulate the data easily can mean the difference between a successful project that quickly pays for itself a long-running headache that never yields the returns you expect.
Fluke: Air leakage is an especially tricky problem to diagnose. Using thermal imaging can show conductive heat loss due to various problems such as missing or damaged insulation. An improperly installed or configured HVAC system could take months to diagnose based on complaints from occupants, but a properly done thermal scan on the HVAC ducting could find the root cause within a day. An active HVAC system can change the thermal patterns, so it is imperative to inspect while the system is running.
CSE: What factors do you need to take into account regarding commissioning BAS or building management systems (BMS)?
Fluke: Primarily, if a field calibration step is required to verify accuracy of sensor measurement and transmittal, then a CxA commonly uses a handheld temperature/humidity meter to verify the sensor readings and a mA or volts dc clamp meter to verify the control signal (Fluke does not manufacture BacNET or other specific building control signal test tools).
Onset: Probably the most significant factor to take into account when commissioning the BAS or BMS is that things change. The way that an automation system was initially configured is never how it is operating six months (maybe even six weeks) down the road. We hear from about customers projects all the time that were able to realize significant savings just by troubleshooting or providing redundancy to a faulty sensor. One faulty sensor can lead to hundreds of dollars of savings per year. Not to mention that the training of facility personnel that have to interact with the automation systems is highly critical. They may be making modifications to make the system operate more effectively but not comprehending its effects on the systems efficiency. Oftentimes the presentation of real data from the automation system contrasted against the independent data logger findings can really reveal the importance of a holistic approach to managing your automation system.
CSE: What types of tools do you recommend for building commissioning projects? What should be in every commissioning agent’s “toolbox”?
Onset: We recommend that our customers working as building CxAs think about keeping a tidy and comprehensive toolbox of data loggers and sensors to assess the performance of a building. You don’t need many – but having a variety of these tools can allow you to save a lot of time at the job site by quickly identifying problem areas. The HOBO UX90 line of data loggers, for example, provide a variety of measurements in a self-contained package that can help you identify when equipment is cycling too frequently or when lights are on but the room is unoccupied. Our suite of UX100 temperature and relative humidity loggers can help spot trouble areas that might uncover critical re-commissioning requirements of the HVAC system. And many of the loggers we’d recommend for a commissioning toolkit have flexible analog or pulse-based inputs to allow users to connect pre-installed sensors and meters up to them to collect short term data in a way that’s easy to manipulate without accessing the building automation system. That means that data is gathered more quickly and saves the CxA time during the process.
Fluke: Tools such as a multimeter or clamp meter, temperature/humidity meter, air meter, micromanometer, and light meter are all used to verify ventilation, mechanical, and lighting performance under load. In addition, a thermal imager or visual IR thermometer are used to inspect the building envelope. A mA Volts dc clamp meter is used to verify signal continuity in the controls system.
CSE: What’s the one factor most commonly overlooked when commissioning electrical system projects?
Onset: Commissioning projects that focus on electrical systems often focus at a high level and never probe down to focus on which specific pieces of equipment or areas of a building are using a disproportionate amount of energy. We’ve found there is tremendous value in the right amount of sub-metering for this purpose. It is easy to look at whole building energy use and even to meter the energy use on some of the known high consuming engines within a building, but a lot can be learned from monitoring the kilowatt-hours consumed by various sub-metered circuits within your facility. Sub-metering for temporary commissioning doesn’t have to be complex or overly expensive. Just using a combination of an energy sensor, like the Wattnode in conjunction with our HOBO UX90 Pulse data logger can get you a lot of insight about how much a specific piece of equipment is using and help you formulate whether or not its energy consumed is proportionally relevant to the whole building energy use.
Fluke: The best way to assess an electrical system is to do so while it is in operation. This is where the value of non-contact temperature measurement can shine. Using an IR thermometer or a thermal imager to scan a circuit breaker can reveal overloaded devices, faulty connections, or weak connections. Similarly, scanning electrical insulation material could show movement of heat, revealing either faulty insulation or thermal bridging.
CSE: What unique requirements do HVAC systems have, and what commissioning questions/issues have you helped resolve?
Fluke: HVAC is tricky for many reasons. First, as mentioned earlier, when an HVAC system is active it changes the thermal patterns. So it must be characterized while it is operating, and under various conditions. Second, the weather outside affects the HVAC system more than might be believed. For example, wind will cool (or heat) surfaces. For these and other reasons, a professional thermographer could help characterize a building both during construction and following construction.
Onset: HVAC systems are unique for a couple of reasons; the first being that they come in a wide range of capabilities, sizes, and locations. For example, the modern-day HVAC unit is highly automated and programmed to respond differently based on the climate outdoors, while many buildings are still operating using a 15 or 20 year old HVAC unit that requires manual intervention when the weather pattern changes to accommodate a new damper position, or may not have a variable damper at all. You may also have entire equipment rooms dedicated for an HVAC unit, or you may find you have to climb on top of the roof to get a look at your HVAC. The second thing that is unique about HVAC systems is that to get a full picture of the way they are functioning means combining a variety of measurements together (temperature, relative humidity, kWh, and air quality parameters). While you certainly don’t have to measure all of those things with each commissioning project, it is entirely possible that you’ll want to measure multiple temperature points (inlets, outlets, evaporator performance, etc.). To satisfy both of these unique characteristics, means you want to be prepared with an adequate tool kit of options to complete your commissioning project successfully. You have to be prepared to measure energy as well as relative humidity and be prepared to do that for everything from a modern, programmable indoor unit or an archaic roof-top unit.
CSE: The public comment period has closed, but what’s your opinion about the International Accreditation Service’s (IAS) Commissioning Accreditation Criteria, AC476, Proposed Accreditation Criteria For Organizations Providing Training And/Or Certification Of Commissioning Personnel?
Onset: Building commissioning is an investment that building owners, facility managers, and consulting firms alike need to consider as an ongoing process that should be measured to accurately track results. It is clear that to make this process a financially viable investment, the implementers need to be trained to do the job correctly. With so many different parameters to consider in a commissioning project (from lighting to comfort to HVAC), it is challenging for industry professionals to always be aware of local requirements, let alone broader industry standards. For this reason, the IAS recommendation for accreditation criteria is valuable to assuring that building owners and operators are provided with a high-value-add procedure when they choose to invest in a commissioning project. The challenge for this accreditation will be how it can seamlessly integrate with other standards that exist without causing undue burden on the relatively small commissioning agencies that require these projects to maintain a thriving business. Many commissioning projects with the highest return are run by relatively small, independent consulting firms that need to minimize their everyday expenses to be successful. Time away from the office for further accreditations might drive hardship to these businesses that could threaten their livelihood. On the flipside, we’ve all heard of failed commissioning projects that no doubt would have been significantly more successful had there not been such a lack of education available to the commissioning market. Driving an accreditation process can help avoid those commissioning pitfalls and also protect consumers from investing with firms that have neglected to stay on top of their field.