You’ve see the ENERGY STAR logo on refrigerators and computers, and now you can see it on our own County of Ventura government buildings. Just by following its own standard operating procedures—which include ambitious ongoing energy efficiency upgrades—the County recently won ENERGY STAR ratings on six of its buildings, including the massive Hall of Justice, home to the Sheriff’s Court Services, courtrooms, and related offices.
And as improvements are made to other County buildings, such as the Hall of Administration, those too will soon display the bronze ENERGY STAR plaque.
“If the ENERGY STAR program had a category for jails, the Todd Road Jail and the new Juvenile Justice Center also would certainly qualify,” says Paul Young, the County’s Maintenance Manager. “Our detention facilities are some of our most efficient buildings.”
Buildings that earn the ENERGY STAR are the top performers for energy efficiency nationwide and use about 35% less energy than average buildings.
A strong ally in the County’s energy-efficiency campaign is the Ventura County Regional Energy Alliance (VCREA), a consortium of public agencies within Ventura County which has a partnership with Southern California Edison and the Gas Company to provide training, technical support, and financial incentives for qualifying energy efficiency projects. VCREA is funded by the Public Utilities Commission.
“VCREA has really helped us by identifying energy-saving opportunities and providing engineering expertise. VCREA also provides financial incentives that make some projects more attractive by reducing the payback,” says Young.
Above: Buildings earning the ENERGY STAR must use about 35% less energy than average buildings.
To appreciate all the big and little efforts that go into achieving this smart-building milestone, let’s look at one of the largest of the hundreds of buildings owned or managed by Ventura County: the Hall of Justice at the County Government Center complex.
In 2006 the Hall of Justice earned an ENERGY STAR national energy performance rating of 85, even better than the score of 75 that is considered to indicate top performance on the system’s 1-100 scale. The ratings help energy managers assess how efficiently their buildings use energy, relative to similar buildings nationwide.
Most of the improvements here had to do with lighting & cooling.
Below: Lighting upgrades underway in a Hall of Justice stairwell.
The new “dual-wattage” lights have two lamps; most of the time, when the stairwell is empty, just one is lit (for safety); but when sensors detect activity, the second lamp is lit for improved light output. Prior to the retrofit, the lighting in the stairwells ran at full wattage, all the time
Lighting Upgrades. “Lighting is a big opportunity to save energy,” says Young. Ever-rising electricity costs and new technology make lighting upgrades among the fastest to pay for themselves, typically in about three years. Lighting systems in some County buildings have been upgraded three times as better technology became available, he says.
Fluorescent lighting fixtures were replaced with more efficient T-8 lamps using electronic ballasts. More sophisticated controls, including occupancy sensors that turn off lights when no one is in the room, have helped to significantly reduce the monthly electric bill.
Aside from lighting upgrades, much of the Hall of Justice’s improved efficiency comes from changes to the air conditioning systems. Its pumps—which move rivers of water through miles of pipelines—and fans are being refitted with super-premium efficiency motors. Most motors are controlled by variable-frequency drives (VFDs), which reduce the energy used by a motor by electronically matching the power it receives to the load it is under.
Thermal Energy Storage System. The Government Center uses a somewhat unusual technology, a thermal energy storage system (TES), to cool its buildings. TES systems significantly reduce energy costs by allowing energy-intensive cooling equipment, such as chillers, to operate mostly during off-peak hours when power rates are lower. The County’s chillers cool water which is then stored in underground vaults filled with 250,000 plastic bottles of eutectic salts, similar to the “blue ice” used in picnic coolers. During the night the chillers cool the bottles to about 38 degrees F. and the coolant inside them turns to gel, which holds the coolness. During the day, this stored “ice” is used to meet the buildings’ air conditioning needs. The TES was installed in 1991 with rebates from Southern California Edison.
Above: Super-premium efficiency motors save energy and money behind the scenes.
Below: This aerial photo shows the location of the underground vault that holds the thermal energy storage system. Thousands of plastic bottles, like the one shown here, hold blue ice-like liquid that cools buildings during the day.
Water chilled overnight is pumped through the building to cool it.
Why Can’t We Just Open the Windows?
Temperature is only one factor in determining the comfort level of a building in which hundreds of people spend many hours each day. Humidity is also important. The Hall of Justice uses an “outdoor air economizer system” that senses the temperature and relative humidity of the outside air and decides when to essentially “open the windows” and let in more fresh air.
“I like the air to feel crisp when I walk into the building,” Young says. “Relative humidity of 50% is comfortable,” especially in contrast to the often humid outside air of coastal Ventura.
Some air from outside is always part of the mix circulating through the ventilation system and, when conditions are just right, 100% outside air is pumped in—allowing the mechanical cooling system to take an energy-saving break.
Such careful attention to indoor air quality and energy efficiency explains why a building this size can’t have windows that can be opened and closed by whomever happens by.
Below: This enormous fan pulls air out of the Hall of Justice building as part of the outdoor air economizer system.
Matching the Juice to the Job
One of the least visible but most effective strategies the County uses to save energy is converting its many electric motors to super-premium efficiency ones controlled by variable-frequency drives (VFDs).
Many motor-driven devices, like fans and pumps, operate at full speed even when the services they perform don’t always require it. The operating speed of a motor connected to a VFD can be varied by changing the frequency of the motor supply voltage. The ability to adjust motor speed enables closer matching of motor output to load and often results in significant energy savings.
VFDs are often used in conjunction with sensors which communicate with the VFD. “An example of this is carbon dioxide sensors,” says David Inger, Energy Projects Manager for the Ventura County Regional Energy Alliance. “A crowded room clearly needs more air than a room that’s only partially occupied. Sensors can be used to monitor carbon dioxide levels in a room and, using a VFD, control the amount of fresh air being pumped in.” Wasted electricity is vastly reduced, saving both energy and money.
Because the fluctuating power supply can damage older motors, whenever the County installs a VFD it also upgrades the motor, usually to a high efficiency super-premium motor. Although their efficiency may be just 2% better than an ordinary motor, when coupled with a VFD the savings pile up quickly. On average, it takes just two years for the energy savings to repay the cost of the upgrade—and the savings continue to accrue year after year.
Below: Ventura County Maintenance Manager Paul Young explains that variable frequency drives—non-descript boxes in the basement—are among the most important pieces of equipment for saving energy at the County.
