by Michael Ivanovich — There are over five million commercial buildings in the U.S., and every one of them is wasting energy. Where energy is wasted, safety problems, health hazards, and comfort issues often exist. Where we find energy efficiency, we also tend to find lower operating costs and greater real estate value.
Despite these fundamentals, getting many owners to improve their buildings’ energy performance can be difficult. Commercial building owners are business owners and seek a business case for investing in their buildings. Proponents of energy investments, such as engineers and manufacturers reps, need to quantify potential savings in terms of payback periods, return on investment (ROI), or other economic tools favored by the owner. The field of retrocommissioning, RCx for short, applies the commissioning process, tools, and technologies to buildings that were not commissioned when first built.
Ideally the RCx process has the same whole-building scope often used when commissioning new buildings, such as inspecting and testing HVAC, electrical, lighting, plumbing, and life-safety systems, and the building envelope. It also checks that documentation is complete and that operators are trained in maintaining long-term performance.
Market forces trim the scope of RCx in many cases to focus on energy-only benefits. In those cases, RCx resembles beefed-up energy audits. There are downsides to that, as explored in this article, but for the most part, even energy-focused RCx provides enough benefits to fuel the RCx market to the point where it’s badly in need of capable providers.
Most Cost-Effective in Large and Complex Buildings
The RCx market generally applies to big buildings because of economies of scale. Fixing large buildings is more cost-effective than fixing small buildings in terms of energy savings and the billable hours and expenses of RCx providers. Larger buildings also tend to have serviceable building automation systems founded on digital controls rather than pneumatic (compressed air) controls, which lack the programming capabilities needed to set the schedules, program the sensors and controllers, and generate the trending data that make RCx cost-effective and make resulting improvements last.
As Jay Santos, principal at Facility Dynamics Engineering, explains, “What tends to need fixing on a small rooftop unit or air handler tends to need fixing on the larger ones, and the costs are similar. But the savings are much greater for the bigger systems,” he says. “That’s why it’s not unusual for retrocommissioning to focus on buildings 50,000 ft2 and above.”
An extensive research project on commissioning and retrocommissioning performed by Lawrence Berkeley National Laboratory (LBNL) in 2009 found that the average RCx project cost $0.30/ft2, yielded an energy savings of 16%, and had a payback of 1.1 years. While the report did not find a correlation between building size and energy results, it did find that the more complex the building, the larger the energy savings and thus the better financial performance of the RCx process. Santos puts this data in perspective: “Good candidates for high energy savings from retrocommissioning are complex facilities that use a lot of energy, such as laboratories, hospitals, and data centers. They have high air changes, complex controls, and quality facility staff who take great care of their facilities.”
When they’re working well, the mechanical, electrical, controls, and other building systems are complex enough. But if (or when) an operator leaves a valve in the wrong position or makes a programming error in one of the hundreds of software programs running in a building, it could cause ripple effects that lead to wasted energy and shorter equipment life.
There might be dozens of these types of problems in a building at one time, all interrelated, and many of them might have been there since the building was first constructed and occupied. For example, a thermostat set point of 72°F might be met by having the chiller over-cool the air, which consequently requires the boiler to heat it before delivering it to the space. This is called simultaneous heating and cooling, and there are a dozen or more conditions under which it can occur—none of which are visible unless specifically checked for.
RCx providers may also find where it’s cost-effective to add variable-speed drives, use different types of filters for greater efficacy at lower cost, or make substantial changes to building automation systems. Such upgrades or retrofits are enhancements to systems that were not originally in the design or construction but are fairly common in RCx projects.
The RCx process might also find that a chiller needs replacing, or that it is cost-effective to totally replace the lighting systems. Such projects can take months to approve and accomplish, and they can disrupt several building systems. While RCx projects may help identify these opportunities, they don’t typically include such capital improvements. (See the table for services that may be in the RCx scope.)
Energy Services and the Retrocommissioning Scope
Guidelines exist that outline RCx from several perspectives and to varying levels of detail. Of these, the National Environmental Balancing Bureau (NEBB) standard is the most highly structured. It’s a good document to have, even if you are not a NEBB-certified provider.
Most RCx firms will develop their own processes over time along with software tools, forms, and checklists to help implement them. In addition, the Building Commissioning Association (BCA) and the California Commissioning Collaborative (CCC) have libraries of sample contracts, checklists, and forms to help new RCx practitioners get started. These documents also give building owners resources for understanding more about the services they are contracting to help better manage expectations and the process.
No matter which set of guidelines you’re following, retro-commissioning may seem like standard operating procedure, or what should be standard. But it’s not. Veteran RCx provider and trainer David Sellers, P.E., senior engineer with Facility Dynamics Engineering in Portland, Oregon, put it this way: “RCx is what, 30 years ago, we called operating the building properly.’ When we retrocommission a building, we essentially get the building to where it needs to be and we set it up for ongoing commissioning so it’s easier for the operators to keep it running well.”
So what happened to operating the building properly? According to Sellers, “We have convinced ourselves that we can build and maintain a complex working building for less than the real cost.” RCx, then, is an added process that is needed to do what operators used to be able to accomplish with sufficient budgets and management support, at a time when the systems themselves were generally less complicated.
Who has to be there to make it work? Team members usually include:
- Commissioning firm (lead RCx provider and assistants)
- Building owner or owner’s representative
- Building manager and staff
- Design professionals
- System specialists
- Installing contractors
- Manufacturers’ representatives
- Maintenance service contractors
- Controls contractors
Energy Versus Whole-Building Scope
Some practitioners take a hard stand that RCx has a whole-building scope; it’s about making buildings work properly. “Any energy savings is icing on the cake,” said Steve Wiggins, associate partner at Newcome & Boyd and past president of NEBB. These whole-building RCx providers tend to look critically at energy-focused utility rebate programs. “One of my greatest concerns is that the current energy focus of RCx will effectively damage the market, as has happened with new-building commissioning,” said Wiggins. “If we don’t distinguish RCx from energy audits, we’ll confuse the client base about what true RCx is.”
Wiggins’ concern, shared by other providers, is that if an owner is introduced to the RCx concept through an energy-focused utility rebate program, they might miss having their fire-protection, plumbing, and security systems looked at. The non-energy benefits of having those systems fixed and documented, and having the operators trained to maintain them, could far exceed the benefits realized by the energy-focused RCx system. Furthermore, the more extensive whole-building processes may have found additional savings, with the cost for having the whole-building RCx project could still have been paid for by the energy fixes. Reese, however, counters that utility programs encourage RCx providers to use the utility programs as opportunities to sell owners upgraded services, such as RCx with a larger scope.
Another issue is that utility-based RCx programs can be built to ignore some savings completely (such as gas-related opportunities if the utility is electricity-only), and prioritize specific types of fixes (such as controls measures) based on payback windows. For example, opportunities paying back in less than one year could be up to the owner to fix, and might not even be documented by the RCx team. Will operators ever make the fixes with less-than-one-year payback, and will persistence measures be put in place to see them through the long term?
Sometimes narrowly conceived RCx can expand. Sellers recounts a project in which “the only reason we were in there doing RCx was because the operators were able to make it more palatable via the utility program.” But Sellers was able to convince the owner to make further changes. “We were able to use RCx trending techniques to convince the owner that it would be a good business decision to add a second chiller to a facility that had 1,200 tons of chiller capacity but a cooling load of 1,500 tons,” he said. “In addition to the capacity, the second chiller provided redundancy. Meanwhile, that and other improvements started to show up in the utility bills and persist. This led to more money from the owner for more measures.”
Even without treating the whole building, many utility rebate programs are claiming potential savings of 5%20%, figures Reese says are accurate. “In one of our California utility programs, we’re seeing an average of about 8% electric savings. Buildings are minimally 100,000 ft2, so 8% can add up to a lot of energy savings. About 75% of the measures implemented in this program have individual paybacks of less than two years; 60% under one year.”
Excerpted from the BuildingGreen.com article by Michael Ivanovich “Retrocommissioning: Big Savings for Big Buildings.” The full article, including a list of the best free online Commissioning and Retrocommissioning resources, is available online.