Rooftops Provide Flexibility For Tilt-Up Construction
Ingram Micro, headquartered here, is a leading distributor of information technology products and services worldwide. Its campus consists of three gleaming white buildings, which house executive offices, accounting, marketing, and a full range of other administrative services. These buildings are a combination of two and three stories of a tilt-up, pre-cast concrete and dryvel panel system construction.
Because this construction method does not require a large internal pillar, it allows great flexibility in building use. This feature is important for a frequently changing application, such as the Ingram Micro campus.
In the eyes of those who maintain such buildings, the cooling of choice for such construction is large rooftop units.
“The units go in quickly and match up well with tilt-ups’ low-rise construction,” said Blair Boyce, from Trane Los Angeles. “With large rooftops, you can get the variable air volume (VAV) air distribution feature, great building pressure control, and you can actually put air at the right temperature anywhere in the building.”
SOLD ON ROOFTOP UNITSStan Szafirowski, air conditioning specialist responsible for operating and maintaining the HVAC facilities in the three buildings, said he relies on packaged rooftop comfort equipment. In this case, there are three Trane Intellipak™ Model SXHF units in place. In his eyes, the unit’s VAV feature is perfect for work space redesigns, which go on constantly at Ingram Micro.
“Just by changing the settings on VAV boxes, Stan can accommodate lots of different floor plans,” said Boyce.
Szafirowski agreed that the advantages of the package rooftop system have been proven by the company’s experience.
“It was also a matter of low initial cost for the units, which was important to our management when we moved onto this site in 1992,” he said.
The 1600 building has six 75-ton units and two 60-ton units. The 1610 building has four 110-units. The 1700 building has four 50-ton units and two 60-ton units. The 1610 building was enlarged and remodeled in 1996. This particular building has a group of small package units for some of the perimeter offices.
All of the large rooftop units are controlled by Trane’s Tracer Summit‘ building management system. Szafirowski is able to monitor and log unit operation from his office or laptop.
Szafirowski indicated that the large units also do a good job of controlling humidity during the winter months. Santa Ana has a near-marine climate, with about 850 cooling degree-days in a typical year. Because of the mild climate and significant internal heat load, heating is necessary only in selective areas of the building.
In compliance with local zoning ordinance, the rooftop units are surrounded by screening enclosures and, therefore, are not visible from street level. The setback of the enclosures from the units is sufficient and normally doesn’t interfere with access for maintenance operations, noted Szafirowski.
He also has partnered with a service company to perform routine quarterly maintenance.
“They check refrigerant pressures and motor amps, tighten terminal lugs, lubricate bearings, and replace filters and also replace belts, as needed,” said Szafirowski, adding that condenser and evaporative coils are chemically cleaned on a semi-annual basis.
The newly installed variable-frequency drives are also cleaned and inspected on a semi-annual basis.
Boyce concluded that this type of relatively simple maintenance with rooftops makes them the system of choice for many owners.
“And there’s the fact that it is not necessary to maintain a chilled-water system or cooling towers, so companies like Ingram don’t need a big staff of operators or technicians,” Boyce said. “That’s why we see so many of them [rooftop units] on commercial buildings in Southern California.”
Publication date: 06/24/2002