Among the challenges posed by the rehabilitation of a long-unoccupied office building in Towson, MD, were restrictive floor-to-floor heights and the owner’s desire
for LEED certification and Class A office space.
The 15-story, 170,000-square-foot Towson City Center was
completed in 1967. Alleged ventilation problems and a reputa-
tion as a sick building led to
the facility’s closing in 2002. It
remained unoccupied for more
than 10 years until new owners
undertook a giant renovation
project, which included me-
chanical and electrical systems
For Steve Wagner, direc-
tor of engineering for design/
build mechanical firm MEC2,
the gutted tower had limited
space for new ductwork. The
floor-to-floor height on 12 of the building’s floors is only 10 feet,
6 inches. To earn LEED certification, energy efficiency was also
a top priority for the new HVAC.
The choice of a Mitsubishi Electric VRF system met those requirements. “We knew that if we went the VRF route, the sheet
Listed on the National Register of Historic Places, the former Imperial Hotel in Atlanta was built in 1910. Gutted and converted into subsidized residential housing units,
the building is now known as the Commons at Imperial Hotel.
The renovated building has more than 90 housing units, which
made it a good fit for a VRF solution.
The building needed individual HVAC controls for each
apartment but the rooftop area was too small to accommodate
so many split-system condensing units. However, the VRF
vice president of
tial, the VRF system
also increased the
area of the housing
units by eliminat-
ing many vertical
metal could be kept to a
minimum,” says Wagner.
The low, 9 7/8-inch pro-
file of the indoor fan coil
units also saved space.
On the building’s pent-
house mechanical level
there was more space to
be saved. With no need
for the cooling tower
and boiler of the previ-
ous central system, this
equipment was removed.
The small footprint of the
VRF system’s 15 outdoor
units (one for each floor)
freed up 12,000 square
feet of the penthouse for
storage or other uses.
A dedicated outside air
system with energy and desiccant recovery wheels was in-
stalled on the steel grillage of the former cooling tower. The
rentable square feet on each floor was increased due to the
reduction in vertical shaft space needed for ventilation.
EXTREME MAKEOVER INCLUDES VRF
UNCOMMON FLEXIBILITY AND EFFICIENCY
ventilation shafts. Indoor fan coil units for the VRF system were
installed above the ceilings in the apartments.
The VRF system’s heat recovery capability was also impor-
tant for efficiency. Barfield explains that the north and south fa-
cades of the building had large
expanses of historic metal bay
windows but the east and west
facades had much less window
area. As a result, indoor tem-
peratures on different sides of
the building were often unbal-
anced. The VRF system allows
heat from warm zones to be
transferred to cooler zones
instead of rejected to the out-
side. Residents also have a high
degree of control over heat and
cooling within their units.
The building’s renovation
was designed to achieve LEED
VRF APPLICATIONS IN THE PRIVATE SECTOR