801 Grand (Principal Financial Group + JLL)

Energy Modeling, Assessment, Troubleshooting, and Improvements

Energy Modeling, Assessment, Troubleshooting, and Improvements - Des Moines, IA


Owner Principal Financial Group and management firm JLL hired G/BA to assist with LEED EB: O&M certification and to improve indoor environmental quality pertaining to air infiltration during cold weather. G/BA prepared a Level 3 energy audit, including a calibrated energy model, and devised ways to reduce pressurization to improve conditions in the lobby and skyway connections. In addition, many recommended energy conservation measures and some capital improvements were implemented.


Source Award
ASHRAE Illinois Chapter 2017 Excellence in Engineering Award
ASHRAE Region VI 2018 Technology Award (First Place, Commercial - Existing Building Commissioning)
ASHRAE Society (International) 2019 Technology Award (First Place, Commercial - Existing Building Commissioning)


801 Grand is a 44-story office building constructed in 1989. The podium levels include retail shops and restaurants, as well as a lobby and parking. The building is all electric, other than natural gas for cooking and for retail tenants in the podium level.

Building owner and primary tenant Principal Financial Group desired building improvements in preparation for consolidating its own office space elsewhere in Des Moines, opening more space in 801 Grand for tenant rentals. In addition to saving money and demonstrating sustainability through LEED EB: O&M certification, Principal and its management firm, JLL, wanted to improve conditions for occupants by addressing air infiltration and pressurization issues.

  • CONTAM modeling indicated that physical barriers to air infiltration would be more effective than HVAC-based countermeasures. New doors were installed on the skyway linking 801 Grand to other buildings, and high-speed doors were added to the parking levels.
  • A Level 3 energy audit, done as a collaborative project between JLL and G/BA, resulted in recommendation of energy conservation measures. Current-sensing data loggers were employed to collect data; G/BA and JLL also did off-hours walk-throughs to help assess conditions when occupancy was low.
  • Eleven low- or no-cost measures were implemented, totaling $224,515 in annual savings, with a payback of less than a year. In addition, seven capital improvement measures with a longer payback were implemented, in line with the client’s goals for a deep energy retrofit. Total bundled implementation costs were about $3.05 million, with verified annual savings of $424,175 and a combined simple payback of 7.2 years. 
  • Lighting and controls retrofits on tenant floors also provided cost savings for the occupying firms.