Facilities around the country are seeking ways in which greater efficiencies can be derived through HVAC systems.
By Carol Brzozowski
Comprehensive Renovation and an NYC HVAC Upgrade
The New York City Center, in New York, is starting to derive energy savings through a recent retrofit also designed to improve the comfort level of occupants, performers, and visitors. New York City Center includes a 2,257-seat auditorium, two small theaters, four rehearsal studios, and a 12-story office tower. As part of a comprehensive renovation project to enhance the lighting, seating, site lines, walls, carpeting, dressing rooms, and stage floor, the New York City Center also endeavored to improve the comfort of performers and audience members through an HVAC upgrade. The work was completed in October 2011.
In addition to increased comfort, the New York City Center also sought energy efficiency, reliability, and enhanced air quality as part of the upgrade. To meet that goal, Trane was chosen to assist with equipment and control upgrades. Flexibility was another criterion as the New York City Center sought to use only what comfort level was necessary when the smaller stages are in use while still being capable of cooling a packed house during a main stage performance. A smaller, 100-ton chiller was added to work along with two previously installed 360-ton Trane CenTraVac chillers. A 90-ton chiller that served only the two small buildings and was at the end of its life was removed.
The City Center maintains two 360-ton chillers for redundancy in case one of them goes down, says David Ward, senior director of facilities and capital planning for the New York City Center.
“We found that we didn’t need that capacity most of the time, so we installed a 100-ton chiller, and we are now running that 80% of the time,” says Ward. “We only run the 360 when we have a full house, all 2,200 seats are filled, and it’s a hot day. Most of the time in rehearsal situation, the 100-ton chiller is quite satisfactory.”
At the time the new 100-ton smart chiller was installed, the New York City Center also did repiping, so either the 360- or the 100-ton chiller can serve the small theaters. Ward says the New York City Center doesn’t run the system fully automated, “because we like to keep it hands-on. Our conditions are always changing, but when we get it set up for particular conditions—such as a rehearsal for a performance—it runs automatically and keeps everything balanced at the set points all of the time. That’s really good for us.”
Performers and visitors appreciate the new system, Ward notes.
“When we upgraded controls, we also made some upgrades to the air distribution system,” says Ward. “We found that one of the major return fan ducts had been disconnected by some contractor years ago, and we were not aware of this. We reconnected it, and we were able to get the performance out of the system that we were supposed to get six years ago. Since that has happened, we have had virtually no air-conditioning complaints.”
The comfort requirements on the large stage and in the 2,200-seat theater are quite different, Ward notes.
“Since this is primarily a hall for dance, dancers like to have the stage very warm to keep their muscles limber,” he points out. “At the same time, we want to keep the auditorium cooler for audience comfort.
“In spite of the fact that these two spaces are coupled by a large, wide-open proscenium arch, we try to condition them and almost treat them as separate rooms. The design of both the Trane controls and our air distribution system allows us to do that.”
Mark Weldy, business leader for Trane’s EarthWise Systems, says the approach taken at the New York City Center is common to Trane’s energy retrofits.
“We add controls, make better system decisions, and coordinate the space with the units that serve the space to try to optimize those conditions,” he says.
The New York City Center also is an example of how Trane approaches retrofits in historic spaces. “In today’s economy, those cost pressures make efficiency a very real challenge for people,” he adds.
In response to market needs, Trane continues to make ongoing improvements in core equipment technologies to drive efficiency. A second area of focus for Trane is adding options in specific configurations that save energy on the equipment, such as heat recovery, economizers, and variable speed drives to compressors and HVAC products that might not have had them before. The use of smart controls is a third area in which Trane is engaged in its efficiency efforts.
Another advancement in HVAC efficiency is moving from the idea of units to systems, Weldy points out.
Thus, going beyond the unit to the system in which it is installed offers opportunities to gain broader usage for HVAC users. That can involve a pre-configuration of design concepts to achieve efficiencies. The approach is to “make it easier for designers to design around them and easier for owners to put them into place—smart equipment, efficient equipment, and optimizing control schemes that lay across those pieces of equipment,” says Weldy.
“When you get into special situations like a historical building, you need to have a lot of options in your portfolio because the space you’re given might allow a few big units, a lot of small units or some mixture in-between,” explains Weldy.
“Retrofits in general would often use a mixture of standard factory product and maybe even some custom product,” he adds. “Sometimes a custom air handler to fit in a space in an available mechanical room becomes a part of the solution for delivering comfort with energy efficiency. Sometimes we can get that by building a custom air handler and putting the right kind of performance options inside of it.”
The appropriate approach matches the occupants’ schedule.
In the case of the New York City Center, not only does the system take into consideration the performers and audience, but there also are office workers housed in the building.
“We’ve put some of these technologies in place to help us deal with partial load situations where the whole building isn’t occupied, but will respond well at full load conditions where you have a space full of people where you need to deliver capacity,” says Weldy.
Some system installation strategies help deliver that capacity in a minimum amount of space.
“A common strategy would be to deliver especially cold air, which lets us run much smaller ductwork in a space than a traditional installation,” says Weldy. “In an historical retrofit like the New York City Center, that could be very significant.”
Moving less air with smaller ductwork also helps the acoustic performance, he adds.
Standalone and Grid Connected
Benz Research and Development in Sarasota, FL, produces soft contact lenses and intraocular lens materials and conducts research for future technologies. The company has three 30-ton Yazaki water-fired chillers, as well as four Capstone 65-kW, 480-V natural gas microturbines to provide 80% of the facility’s full load 480 V power and 90% of its hot water at 85°C (185°F). All turbines work in dual-mode configuration, meaning they can produce electricity as per customer needs when in grid connect mode when power from the utility is available, but run in standalone mode during power outages to support plant manufacturing.
Benz also has constructed a modular, self-contained standalone system with one turbine and one Yazaki chiller that can be reproduced or modularly expanded to help meet future needs. It has an option for water condensation from the exhaust gas at the rate of about 200 gallons a day.
Rakesh Vasant, manager of operations and process control for Benz Research and Development, says the company had three reasons for installing the turbines in 2008 and then creating a Combined Cooling Heat and Power (CCHP) system in 2009.
The first: “We have been conscious towards how the environment can be conserved and companies’ social responsibility with respect to the environment,” he says.
The second was that the company’s Florida location makes it prone to power outages when hurricanes pass through the area.
“This is the hurricane capital for the country and there are all of these chances of getting either surges, spikes, or power outages that can be destructive to our business,” says Vasant. “We wanted to get a redundancy from these interruptions in power and be able to protect ourselves as a reliable supplier of materials worldwide, even in the case of hurricanes that happen in Florida.”
The third reason: a robust manufacturing environment tied into energy efficiency.
“Energy efficiency was the leading goal for the turbines we use for power generation, which gives us waste heat that can be used for air conditioning our facility, and for our energy conservation initiatives,” notes Vasant.
“Since we wanted to have power redundancy and couple it with heat recovery, we have the Capstone turbine chillers onsite for power generation, which gives us backup power in case of an emergency,” he adds.
Benz recovers the waste heat with custom heat exchangers designed in-house and with outside contractors.
“We built the whole combined cooling, heat and power system to work in tandem with the turbines. It takes all of the heat in one large plenum to run it through heat exchangers where we recover that waste heat into hot water and use it for the Yazaki chillers,” says Vasant.
The system has helped “tremendously” in saving money on a regular basis, Vasant notes. “In contact lens manufacturing, the environment has to have very low humidity, because the product is very humidity sensitive,” he says. “We try to use the Yazaki chillers to cool down the water. Our system is based on chilled water, so we use the system to cool down the chilled water sufficiently, and then we take it further down for low humidity.”
The cost savings from waste heat recovery and the increased energy efficiency of the CCHP system has provided Benz an approximate energy savings of $60,000 a year with an overall thermal dynamic efficiency of greater than 70%.
Installing a High Efficiency System
In Georgia, the Jackson County Board of Education had been seeking an efficient, cost-effective air-conditioning system for the North Jackson Elementary multi-use gymnasium, which never had air conditioning. The metal-framed gym houses a full-size maple hardwood basketball court, offices, and restrooms. It serves to host daily physical education classes, as well as other school functions, such as assemblies, graduations, and general meetings.
A traditional air-conditioning system would have cost nearly $52,000 for a package unit on the ground and fabricated ductwork installed up one side of the building, through the gymnasium wall, and down the gym’s center. Also part of the costs would be converting the 200-amp single-phase electric service to three-phase for a 30-ton package unit. Like most school systems nationwide, the Jackson County Board of Education faced budget restrictions.
In June 2011, Josh Patton, the HVAC foreman, used LG Multi-F products for supplemental cooling in the cafeteria space instead of adding ductwork. Pleased with the duct-free system’s performance and efficiency in the cafeteria, Patton advocated for using LG Flex Multi-Quad Zones in the gymnasium. Another cost benefit would be that the work could be done in-house.
Using load calculations, Patton designed a system that includes units around the perimeter of the gym discharging air towards the center with ceiling cassettes in the center of the gym discharging air in a four-way pattern. The systems were installed on the existing electric service. Before installing the air-conditioning system, Patton and his team changed out the lights, adding 400-W metal halide lights and putting in T-5 high-output fixtures.
“That dropped our amp draw,” says Patton. “We were pulling 76 amps per leg coming into the building and it dropped it down to 26, which gave us enough power to install the air conditioners. We didn’t have to do any electrical upgrades to the gym to add air conditioning.”
The system entails 22.5 tons of cooling in running on a 225-amp single-phase service. Inverter systems enabled Jackson County Schools to remove space heaters, which eliminated the winter gas bill for heating the gym. The costs of installing the high-efficiency system were offset by a rebate provided by Georgia Power. Patton indicates the school saved in excess of $10,000 by using the LG Systems even before factoring operating savings.
Because the gymnasium went from no air conditioning to having it, the power bills have increased by $300 to $400 a month, but because of the efficiency of the system, Patton says those numbers are good. The work was completed in April 2012. The gym maintained a set point of 68 degrees during a May 2012 graduation ceremony hosting 400 people. Occupants have enjoyed the air conditioning, Patton notes.
“They went from a 100-degree gym when it’s hot outside, to a 72-degree gym,” he adds. “They used to start school in September. Now it starts the first of August. So when it’s 100 degrees outside, it was 100 inside. The kids could not use the gym. They’d have to make other arrangements for them, either outside or in the classroom. Now we get full use of the facility.”
Because the work was done in-house, there was no downtime for the gym.
“Traditionally, you’d have to put in duct work, and you’d be all over the gym,” says Patton. “With the LGs, we were in specific areas each day, so the kids were actually in there with us. We’d just block off an area, and they still had full use of the facility when we were doing it.”
Author’s Bio: Carol Brzozowski writes on the topics of technology and industry.