VRF Breathes New Life Into Skyscraper
According to the U.S. Census Bureau, Detroit lost 60% of its population from 1950 to 2010. However, in the last two years, something has shifted. Downtown activity has greatly increased thanks to a focus on rehabilitating historic buildings.
Several projects are credited with this revitalization — including the $94.5 million renovation of the David Whitney Building. The building has been restored to its previous grandeur and now offers luxury residences, the Aloft hotel, a restaurant, and a bar. Key to that renovation was retrofitting the entire building with over 600 tons of VRF technology from Mitsubishi Electric U.S. Inc., Cooling & Heating Division.
Vince Dattilo, vice president of construction and project management at Roxbury Group in Detroit — the developer on the job — knew his team had a big project ahead of them. The building dates back to 1915, and sat vacant for 15 years before the renovation. The outdated mechanical systems needed updating, but the sheer size and mass of the preexisting structure presented an immediate problem.
“The floor is 22 to 28 in thick. So right off, that made new HVAC challenging from a cost perspective. Forced air, which involves running tons of ductwork, would have meant high costs — if ductwork was even possible,” said Dattilo.
He continued, “At the same time, we were interested in bringing a more efficient and ductless cooling and heating solution to Detroit: VRF. People were skeptical — contractors said it was more expensive and you couldn’t afford it. We proved them all wrong.”
Cue Don Nichols, P.E., senior mechanical engineer for Strategic Energy Solutions in Berkley, MI. Nichols was brought onto the team and given two determining factors whether VRF was in fact the most viable HVAC system: cost and energy efficiency.
He said, “Cost was about first cost. We compared two types of systems — water-source heat pumps and VRF. The construction cost for the VRF came in less than water-source heat pumps.”
Dattilo explained that the VRF design used “a pre-insulated line set distributed locally and manufactured in Italy. We were looking at close to five miles of piping, so compare VRF to getting guys in here crawling through tight spaces to install insulation — that’s a lot of money saved on that one piece alone.”
Nichols’ consideration of “energy efficiency was about long-term utility cost. We did energy modeling for the building, looking at the yearly energy cost compared to a baseline of typical HVAC. Ultimately, VRF was a lower first cost installation and lower utility operating costs.”
The result was that the original estimate of $6.8 million with a forced-air system came down to $5 million with VRF. Dattilo said, “That’s the point where we said VRF makes sense financially. Forget about the energy efficiency and lack of ductwork, getting the right number is super important.”
VRF not only brought the price down, it solved another key project requirement of maintaining the building’s existing architecture. Contractor Rick Mead, president of RW Mead & Sons in Fraser, MI said, “We could not disturb any of the historically significant elements of the building. To solve for renovating the historic building, VRF with its small-diameter piping rather than large-diameter forced-air ductwork made sense.”
Despite all of the cost concerns and the building’s structural challenges, “The installation went very, very well,” said Mead.
Nichols’ design split the condensers across three areas — on the roof, in an alley, and in the basement level areaways — to minimize the vertical travel distance of line sets, thereby staying within the Mitsubishi Electric specification.
Since installation, the VRF system has been keeping everyone comfortable while keeping costs down.
Mead said, “In January/February, the system was put to a test, and it provided the heat needed to make people happy and comfortable.”
Behind the scenes, the centralized controls system has been a boon to the entire building’s management team. Dattilo said, “The BACnet® controls allow you to look at the system remotely — every fan coil, every condenser. We can set alarms. We can see what folks are doing 24/7/365.”
Mead explained that such a high level of control is important because “this way you can fix a problem before it gets ugly.”
Ultimately, Nichols said “The David Whitney is a big player in the Detroit revitalization. It’s been well-received and is in the heart of everything downtown. It’s an iconic place, and now it’s the hot spot in Detroit.”