Tag Archives: Retrocommissioning

Key Findings From Retrocommissioning A High-Performance Building

KLH coordinated multiple tests and reviewed the functional performance testing data and the building’s environmental trend data to find a solution to improve system performance and operating efficiency, and reduce energy costs. Through this research, KLH identified multiple issues, including a problem with the building pressure—the RTU exhaust fan was only enabled when the outside air damper was open above a minimum position and the building pressure was above the building pressure set-point.

The minimum outside air damper position was set to 10 percent on all RTUs and the power exhaust outside air minimum position was set to 20 percent. This set-point prevented the power exhaust from operating and maintaining an appropriate building pressure. After looking at the building pressure trending, KLH discovered that the building pressure would continually rise throughout the day, until approximately 5:00 p.m., when all of the doors opened as employees exited the building. Because the building envelope was secure and the doors remained closed, the building pressure would rise to the point where doors were difficult to close once opened.

To combat this problem, the outside-air minimum damper position set-point (for the power exhaust system) was lowered to 5 percent on RTU #4 in an effort to see if the power exhaust fan would engage and maintain building pressure. Once the set point was lowered to 5 percent, the rooftop unit immediately began to exhaust air. After this change, the BAS showed the building pressure decreased until the programmed building pressure set-point was attained.

In addition to these findings, the RCx study uncovered other opportunities, which KLH recommended to further improve the building’s energy efficiency. These projects include: carbon dioxide space monitoring and outside air ventilation control, a new control strategy for supply duct static reset, installing an enthalpy economizer control, and implementing a new supply air reset control strategy.

The success of the RCx project shows how to utilize RCx not only as a means of obtaining LEED certification points, but as a foundation for responsible energy management practices. According to Johanning, knowing that the mechanical systems and controls operating the buildings are working in sync—and efficiently—creates peace-of-mind, and RCx is the vehicle to deliver those results. Not only did the Springfield RCx project exceed Johanning’s expectations, it also expedited the funding approval process for some of the recommended corrective actions to further enhance efficiency.

The Springfield RCx project was so successful that the business is planning to conduct RCx studies in selected facilities throughout its commercial office portfolio to further drive down operating costs. RCx is proven to be a smart choice for facility managers and building owners who want to streamline their building’s performance and operations. Doing so can further improve building efficiency, save monthly costs, and ensure happier employees with more comfortable working conditions.

Jerry Schmits is Director of Energy Solutions at Kohrs Lonnemann Heil Engineers. You can reach him at jschmits@klhengrs.com.

Retrocommissioning Improves Energy Efficiency In High-Performing Buildings

LEED certification and Energy Star benchmarking continue to grow in popularity for existing buildings as pressures mount to control operating expenses. As a result, energy efficiency is now mainstream, and managing a building’s energy performance is standard procedure among an ever-growing number of facility managers.

Energy Manager Patrick Johanning is one of them. Johanning works for an international commercial real-estate services corporation, where he manages energy cost and consumption for a Fortune 500 financial services company. Acting on a hunch that he could improve energy efficiency and reduce operating costs among his top-performing facilities, Johanning looked into retro-commissioning (RCx). The result was an RCx project in Springfield, Ill. — performed on a building that was LEED Gold certified with an 89 Energy Star score — which managed to produce a 10.4 percent energy savings on its HVAC system.

Multiple options existed for reducing the energy-related expenses, including energy audits and re-lamp projects. But while the benefits of these activities are well documented, the state of efficiency that existed between the facility’s mechanical and operating systems, and the control systems that function on the front-end, was not documented. While the RCx process is intended to restore a building’s equipment and mechanical systems back to their original operational design, functional performance testing can also improve energy efficiency. In short, if Johanning could show favorable RCx results in a high-performing building, he could find support for an RCx program across the entire commercial office portfolio. The first challenge was to both prove his hypothesis and get the project funded.

The funding arrived in the form of an RCx study rebate provided by City Water Light and Power (CWLP), the power utility company serving the building’s area. Johanning then hired Kohrs Lonnemann Heil Engineers (KLH), an engineering firm with experience in energy solutions and the RCx process, to help restore the building’s systems back to their optimal operational state while focusing on potential energy saving opportunities. The following details how KLH worked with Johanning to reach RCx success.
Beyond the low-hanging fruit

A review of the current facility requirements confirmed that there had been no material changes in the building zoning or use of the facility from its original design and construction.  Based on this information, the scope of the project was designed to focus on domestic hot water, snow melt, lighting, and HVAC. There were no blatant, major equipment or operational issues; preventative maintenance practices were in place; and the building was in exceptional physical condition. However facility staff interviews uncovered some issues related to fluctuations in the building pressure.

Functional performance testing of the HVAC system and testing of the BAS revealed discrepancies in the airflow throughout several of the VAV boxes. In addition, data from the BAS showed a steady increase throughout the day in the building pressure, and that the exhaust fans were not properly maintaining appropriate pressure levels. But despite these pressure levels, carbon dioxide levels only reached 75 percent of the maximum acceptable levels for indoor air quality—well within the ASHRAE minimum standards. The absence of obvious energy conservation measures—the low-hanging fruit—meant that the success of the RCx project would be an even greater challenge.