ASHRAE Region VI Honors Two G/BA Projects
G/BA's work at a large commercial property and at six Advocate Health Care hospitals has been honored with the ASHRAE Region VI Technology Award.
The firm’s Assessment, Modeling, and Improvements project at 801 Grand in Des Moines, IA, received First Place in the Commercial Buildings – Existing Buildings Commissioning (EBCx) category. A Boiler Plant Optimization project for Advocate received Honorable Mention in the Health Care Facilities – Existing category.
These projects were previously awarded the 2017 Excellence in Engineering award by the Illinois Chapter of ASHRAE.
801 Grand, Assessment, Modeling, and Improvements
801 Grand is a 44-story office building in downtown Des Moines, IA. Originally constructed in 1989, the building includes podium-level retail shops and restaurants, as well as a lobby and parking garage. It is an all-electric facility, other than natural gas for cooking and for podium-level retail tenants.
The facility was acknowledged for the analysis and improvements that occurred during between 2012 and 2016. 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.
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. Principal Financial wanted to improve the building in preparation for consolidating its own office space elsewhere in the city, opening more space in 801 Grand for tenant rentals.
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.
The Level 3 energy audit, done collaboratively with JLL, resulted in recommendation of energy conservation measures. Current-sensing data loggers were used; 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 $244,515 in annual savings, with a payback of less than a year. Significant items in this category included seasonal adjustments of the HVAC schedules; turning off bathroom exhaust during unoccupied periods; and changing lighting schedules.
In addition, the client elected to implement seven capital improvement measures with a longer payback, in line with its goals for a deep energy retrofit. Total bundled implementation costs were about $3.05 million, with verified annual savings of $424,157 and a combined simple payback of 7.2 years.
Lighting and controls retrofits on tenant floors also provided cost savings for the occupying firms.
The project was a collaborative effort that involved not only the G/BA team and JLL, but also significant input from the facilities staff and contractors. G/BA staff John Tsingas (Vice President) and David Eldridge (Associate) led the project team.
Advocate Health Care, Boiler Plant Optimization Program
An energy efficiency initiative involved optimization of nine steam boilers at six Advocate Health Care sites in Illinois. Boilers were retrofitted with boiler flue stack economizers, domestic hot water preheaters, and deaerator tank vent condensers. Sites receiving upgrades were Christ Medical Center, Oak Lawn (1,310,924 square feet); Condell Medical Center, Libertyville (746,004 square feet); Good Samaritan Hospital, Downers Grove (1,059,606 square feet); Advocate Good Shepherd Hospital, Barrington (468,723 square feet); Illinois Masonic Medical Center, Chicago (1,143,379 square feet); and BroMenn Medical Center, Normal (446,000 square feet). All six sites have typical building areas for hospitals (patient rooms, operating rooms, clinical labs, offices, common areas, and associated support space).
All campuses except BroMenn had been updated with high-efficiency boiler burners a few years before the current initiative began.
The boiler optimization project included three components designed to recover waste heat from the hospitals’ steam boiler systems: flue stack economizers, heat exchangers/controls, and vent condensers at the dearator tank bleed vents.
- Primary heat recovery is provided by boiler flue stack economizers, used to preheat boiler feed water entering the boiler steam drum. Typical performance provides for 20°F to 25° F preheating of boiler feedwater, reducing the amount of natural gas required for steam production.
- The second component of the project included a heat exchanger and controls for preheating domestic hot water utilizing the bypass steam of the flue economizer boiler feed water. With stack economizer systems, it is necessary to bypass a small percentage of water at the economizer outlet back to the feedwater tanks to prevent “steaming” and/or pressure buildup in the feed water system. The bypass steam is superheated water, typically 250°F at 150 psig, that will flash to atmosphere and be wasted if sent directly to the condensate surge tank. The design provides for preheating make-up water to the domestic water heaters and reducing the boiler feedwater temperature bypass down to a temperature where flashing is eliminated. The bypass steam is returned to the condensate tank at 190°F, where it also provides the benefit of increasing the surge tank temperature, improving the degasification process, and reducing deaerator steam demand.
- The third component of the project provided vent condensers at the deaerator tank bleed vents to recover waste steam and preheat make-up water to the condensate surge tanks. Boiler deaerator tanks are designed to remove dissolved gasses in the feedwater, which are detrimental to water quality and increase corrosion in the steam and condensate distribution piping. The gasses are purged by venting steam from the deaerator spray chamber in a vent pipe to atmosphere. By installing a vent condenser heat exchanger, the wasted steam is reduced and heat is recovered by preheating the make-up water entering the condensate surge tank.
The image below depicts system components at Advocate Good Shepherd Hospital.
Advocate Health Care received incentives from local utilities to support the retrofits, amounting to about 17% of the total project construction cost. The simple payback is projected to be 8.2 years after considering utility incentives. Adovcate’s operating costs will be reduced by about $184,000 annually due to increased boiler plant efficiency and reduced gas consumption.
G/BA team leaders for the project were Dan Doyle (Chairman) and Tim Jendrycki (Associate).