Project profile: VRF systems installation at century-old bank

VRF technology saves 41% on energy costs within first year of installation for century-old building.


The Mitsubishi Electric units. Courtesy: Drinkard Engineering Group Inc.Project name: Century Bank & Trust
Project type: Existing building retrofit
Engineering firm: Drinkard Engineering Group Inc.
Building type: Office buildings
Location: Milledgeville, GA 
Timeline: March 2012 - April 2012

Building details

Century Bank & Trust is an independent community bank that has been in operation since 1898. The bank is housed in a 24,000-sq-ft, three-level building that was remodeled about 25 years ago.

The interior of the bank. Courtesy: Drinkard Engineering Group Inc.Project challenges
Century Bank's renovation 25 years ago combined two separate buildings. The renovation also included the installation of a water-source heat pump system. Water-source heat pump systems rely on both electricity and chilled water to deliver the required heating and cooling. Brian Robinson, vice president of Century Bank, said, "At the time, it was a state-of-the-art system. Now it's not. This is a 100% on, 100% off system." This inefficiency cost the bank greatly; "Our bill ran from $6,000 to $8,000 a month," Robinson said. "Then there were the leaks." Meanwhile the employees were uncomfortable: "We had heaters at every desk, contributing to the electric bill problem."

Robinson called in Air Conditioning Specialist Inc. (ACS) to study the situation and propose a solution. ACS gathered data on the building's energy use via modeling software. There were analyzed scenarios: to put back the same system the bank had, to put in a non-variable refrigerant flow (VRF) zoning system, and to put in a VRF zoning system. The bank's previous system was outdated and aging quickly, but it did offer 20 zones. The bank didn't want to lose that zoning capability, and in fact hoped to have even more zones such that everyone could have their own control.

Energy usage chart. Courtesy: Drinkard Engineering Group Inc.Another significant item on the wish list was the bank's commitment to staying open throughout the installation. Finding a system that satisfied the bank's energy savings and zoning requirements while allowing minimal installation impact could have provided an insurmountable challenge.  

Project solution
The team concluded that three Mitsubishi Electric VRF zoning systems would check off every need. The team previously completed several large-scale installation projects, including schools and large warehouses. The team set out to design the new HVAC system, working closely with the bank to ensure that the installation would not interrupt the building usage.

Installation began in March 2012 and was completed within one month. The bank remained open the entire time, with the installation happening at night. The team worked on one system per floor, at 20 tons per floor, installing the systems one by one. This method minimized the amount of movements. ACS removed and replaced the entire existing chilled water system, and then brought in and installed over 60 tons of Mitsubishi Electric equipment.

Project result
The installation was completed in April 2012 and the bank saw enormous reductions in energy usage. Robinson said, "We saw an energy savings of more than 28%." The bank additionally saw reductions in water consumption of about $100 per month. 

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