ASHRAE Journal - April 2014 - 22

Technical FeaTure

(Left) Slot diffusers run along the perimeter ceiling. (Right) Air quality satisfaction increased from 26% in 2005 to 77% in 2010 and 70% in 2013.

inverters are operating properly. The array consists of
a total of 120 panels, which generate a 600 V dc voltage.
Four dc/ac inverters convert this voltage into a 208 ac
voltage, which is fed to the utility grid.
Lessons Learned Increasingly, one or another of the system's
four power inverters routinely goes off-line and must be
reset manually, which requires climbing a ladder to the
roof level. Each such outage cuts capacity by 25%.
The original installer has tried to correct the product
defect with no success. Also, the specific inverter manufacturer has since been dropped by the PV system supplier. Once a new, more reliable, set of inverters is identified and installed, the operating status of each inverter
should be closely monitored for similar faults and annunciated through the building automation system.
We also learned that the installer did not install
a shield over the inverters to prevent overheating
caused by solar heat gain, especially in the summer, as
required in the manufacturer's installation manual.

Power Monitoring
Electrical loads were extensively isolated by use and
submetered on separate panels to better understand
how energy is used in the building.
Submetered Panels: first floor lighting; first floor plug
loads; first floor mechanical; second floor lighting; second floor plug loads; second floor mechanical; DOAS; PV
array; computer room (server load + cooling load); outdoor lighting; and water heating.
Lessons Learned Commissioning proved to be invaluable to
the project. We learned, for example, that the six condensers that are part of the DOAS system were not included on
the DOAS submetered electrical panel initially.
22

ASHRAE JouRnAl

ashrae.org

Apri l 2014

In 2009, we were pleasantly surprised that our plug
loads and computer room electrical loads dropped 20%
to 30% after we switched out leased desktop computers
for a thin-client system, and replaced server racks for
blade-type servers. Also, after these changes, the two
ceiling-mounted VRF units that cool the computer room
were each fully able to keep up with the load in the room
on even the hottest summer days.

Water Consumption
Calculated annual flush fixture water consumption
has been reduced by 52.3% for bathrooms and flush and
flow water consumption by 46.3% overall for the building in comparison to a similar-size office building. This
reduction was achieved by using low-flow toilets, waterless urinals, plus reconfigured landscaping to eliminate
the need for irrigation. Landscape water savings were
achieved by re-landscaping the majority of the site with
plant species that are native or naturalized to the piedmont of Georgia. Microclimatic conditions throughout
the site were carefully analyzed to select species that are
specifically adapted to the varying conditions. When
compared with the old building's metered water use, the
savings are even greater, with an estimated 67% reduction in annual water consumption.
Lesson Learned Automatic toilet flush sensors, if not adjusted
properly for male and female users, will waste a large
amount of water due to multiple unintended flushes. Also,
once the approximate change-out schedule is determined
for waterless urinal cartridges, they are very effective and
provide acceptable odor control. To date, no piping system
issues have been identified given the lack of water flow in
the urinals and reduced flush rates.

ASHRAE Journal - April 2014

Table of Contents for the Digital Edition of ASHRAE Journal - April 2014