Case Study: Lex Center

Project Background

When Redbrick Commercial, a Minnesota-based real estate firm, purchased Lex Center in Shoreview, Minnesota, the new ownership team set out to make the building as energy efficient as possible. Dan Alstatt, Redbrick Commercial Principal, needed a clear understanding of existing equipment conditions in the 30,000 square foot, three-story office building before moving forward with bids for major capital improvements. Alstatt was also looking for help with energy benchmarking, identification of practical energy conservation opportunities, and advice on whether aging boilers should be replaced or optimized. 

The building had no automation system, which meant there was little visibility into performance and no effective way to manage schedules or setbacks. Systems were running 24/7, energy use was higher than necessary, and comfort issues were already apparent. For the new owner, Xcel Energy’s Building Assessment (BA) program, implemented by Center for Energy and Environment (CEE), offered a way to increase control, reduce waste, and pair recommended improvements with financing and rebates. 

Investigation and Assessment

Xcel Energy connected Alstatt with CEE’s engineering team who assessed Lex Center’s major energy systems, including two rooftop units (RTUs), variable air volume (VAV) systems, boilers, lighting, and pumps. The ASHRAE Level 2 assessment found numerous energy conservation opportunities that could result in significant cost savings and improved tenant comfort. The RTUs were running continuously instead of being scheduled for only occupied times, setpoints and reset strategies were not optimized, and a variable frequency drive (VFD) was not functioning properly. Existing equipment was not being used to its full potential, and the building lacked temperature setbacks during unoccupied hours.

These issues contributed to both underheating and overcooling, affecting comfort as well as efficiency. Boiler staging controls were also not optimized, and there was no outdoor air temperature reset strategy in place. Overall, the assessment showed that the building would benefit from a focused controls and optimization strategy rather than relying only on major equipment replacement.

Implementation and Outcomes

Over the next two years, CEE helped implement a set of improvements designed to reduce unnecessary runtime and improve system performance. Measures included: 

• Occupancy schedule optimization with optimum start

• VFDs for RTU fans

• Duct static pressure reset

• Economizer lockout optimization

• Boiler outdoor air reset controls

• Additional boiler control improvements

• LED lighting upgrades

CEE’s engineering team also visited the site to verify that the new controls were working as intended and collaborated with the controls contractor to identify additional opportunities for improvement. 

The equipment upgrades and optimization strategies are delivering estimated annual cost savings of $21,543—one-third of the building’s energy costs—and annual energy savings of 185,396 kWh and 7,737 therms. Redbrick Commercial earned $17,014 in rebates from Xcel Energy to offset project costs as part of the BA program, and CEE also helped them access MinnPACE financing. In addition to the savings, Redbrick Commercial gained better visibility into building performance, improved tenant comfort, and acquired a more effective strategy for ongoing energy management.