Walk past many of the vintage skyscrapers and landmark buildings of Detroit’s central business district and there’s a good chance several of them are owned by Dan Gilbert, the founder of mortgage giant Quicken Loans.

Since 2010, Gilbert’s Rock Ventures LLC and its real estate arm Bedrock Services have purchased dozens of pieces of downtown Detroit’s architectural history, from 1960s office towers to casinos and buildings dating to the start of the 20th century. To date, the company says it has invested $2.2 billion and it controls more than 14 million square feet of real estate. 

Among its recent acquisitions was a 36,000-square-foot, 6-story building located at the southwest corner of Griswold Street and Grand River Avenue. The red brick building, which dates to 1897, had been vacant for decades.

Built in a classical revival style, the building’s timber roof was never designed to support the weight of cooling towers, chillers or other types of rooftop HVAC construction equipment. That made updating the building’s climate-control system a challenge for consulting engineer George Hopkins, a principal with Peter Basso Associates in Detroit. 

“We considered packaged rooftops, water-source heat pumps with an evaporative closed-circuit cooler, four-pipe fan-coil system with a rooftop chiller — and they all exceeded the roof’s weight-bearing capacity,” he said.

Hopkins regularly works on unusual HVAC construction projects. He won a technology award in 2001 from the American Society of Heating, Refrigeration and Air-Conditioning Engineers’ Detroit chapter for the HVAC system he designed for an office building in the Detroit suburb of Rochester, Michigan. Other green HVAC projects the engineer has worked on include General Motors’ waterfront world headquarters, the 1929 Guardian Building and the Leadership in Energy and Environmental Design-certified Oakland County International Airport, a small facility that is mostly used by private planes. 

VRF to the rescue

Hopkins eventually picked energy-efficient lightweight variable-refrigerant-flow technology and rooftop equipment mounts designed for strategic weight distribution. Both minimized roof penetrations from ductwork, curbs and conventional fabricated I-beam supports. Their use saved tens of thousands of dollars, officials said.

The building’s renovation was designed by Neumann/Smith Architecture and with the work overseen by Bedrock and general contractor Sachse Construction. As with many of the Gilbert-owned buildings in the city, the building would eventually have restaurants, offices, shops and other uses. 

One of its major tenants, the Detroit Institute of Music Education, uses the building for rehearsals and performances. 

To overcome the roof’s weight limits, Hopkins specified Big Foot equipment mounts, made from tubular, corrosion-resistant, hot-dipped galvanized modular steel by RectorSeal Corp. of Houston. They support 20 Multi-City series VRF condensers rated at up to 325,000 British thermal units, manufactured by Mitsubishi Electric.

The VRF condensers provide refrigerant to 39 Mitsubishi fan coils that supply the majority of air conditioning and some heat through the open architectural ceiling’s rectangular sheet metal ductwork. The building also uses some exposed, painted spiral ductwork.

Manufacturer’s representative Comfort Engineering Solutions of Ann Arbor, Michigan, supplied the equipment mounts and VRF equipment. 

The mounting system’s 12- by 12-inch-square anti-vibration nylon footing pads were positioned over the roof joists to preserve structural integrity and to adequately support the variable-refrigerant-flow HVAC units.

Less noise

The pads reduce vibrations and noise — critical to the institute’s recording studio and rehearsing and performance areas. 

“The anti-vibration feet allowed us to eliminate the expense of conventional spring isolators and other equipment,” Hopkins said. 

The mounts, specially designed by RectorSeal, also cut installation costs 30 percent, said project manager Robert Smith of Complete Mechanical Contracting in Westland, Michigan.

The contractor oversaw all of the project’s HVAC construction. 

The building uses a 7,500 cubic feet per minute air-to-air energy-recovery ventilator from RenewAire of Madison, Wisconsin, to supply outdoor air to the fan coil on each floor. The ERV’s return air is supplied by ceiling plenums, bathrooms and janitor closet exhaust air. Peter Blasso Associates’ engineers put it on the third floor due to the roof’s weight limitations. 

Allen Park, Michigan-based Ventcom was the project’s sheet metal contractor. 

The VRF system provides some heating on extremely cold days — common during Detroit’s long Midwest winters — but the building’s primary heating source is two Harsco Industrial Patterson-Kelley Mach I boilers that supply more than 1,200 linear feet of 1 1/4-inch perimeter baseboard made by Sterling Hydronics of Westfield, Massachusetts. 

Control functions are done by the facility’s building management system, which was installed by Michigan Environmental Controls of New Hudson, Michigan. It uses Niagara equipment by Tridium of Richmond, Virginia, and control and sensing equipment made Milwaukee-based Johnson Controls. 

For reprints of this article, contact Jill DeVries at (248) 244-1726 or email devriesj@bnpmedia.com.