When temperatures soared in late July, it was air conditioning and not electricity that was in short supply at UC Davis.

This explains why the Operations and Maintenance unit shut off air conditioning to certain buildings, including Mrak Hall, student housing, the Activities and Recreation Center and the ARC Pavilion.

Air conditioning priority went to research labs and other "critical mission" facilities, such as buildings that house key computer operations, said Maurice "Mo" Hollman, associate vice chancellor for facilities management.

The heat wave "threatened the fundamental mission of the university," said Hollman, noting this was the first time in his 26 years in this line of work that he had faced such a predicament. His career has not been without other crises: the Northridge earthquake and the Rodney King riots when he was at the University of Southern California; the Loma Prieta quake when he was at UC Santa Cruz; and two major power failures.

With rising temperatures indoors and out at UC Davis, "lab alarms were ringing like crazy," Hollman said. They signaled dangerous heat conditions.

"We went to the edge, and we were able to pull back from the edge," said Hollman, who commended his staff's crisis management.

With more than 20,000 research projects going on at any given time, the university will need some time to determine if any suffered from the heat, especially those outside air-conditioned buildings, said Lynne Chronister, associate vice chancellor in the Office of Research.

"However, we are extremely pleased and appreciative that Operations and Maintenance was able to so effectively identify critical research projects, involving animals and other living organisms, and to balance the needs of the entire university research community."

Dean Ken Burtis of the College of Biological Sciences said he had received information indicating that the temperature approached 84 degrees in two labs that work with Drosophila flies. At 84 degrees, he said, the male Drosophila can become sterile.

Operations and Maintenance went into emergency mode on July 21, and 50 or so people dealt with the crisis for nearly a week. Many of them worked 24 hours a day, seven days a week, Hollman said. During the critical weekend of July 22-23, many employees returned to campus on their own, without being called in.

"I can't express how appreciative I am," Hollman said. He commended his staff of "heat wave heroes" for their "creativity, initiative and mutual support in problem solving."

"The front-line men and women served this institution well."

And they did so while working with what Hollman described as an "aged and in some cases obsolete" cooling and controls system. Four days before the heat wave began, one of the campus's chilling units broke down, Hollman said. His crew had the unit up and running again July 21 — just in time for the heat wave.

The campus's cooling system proved no match for seven consecutive days of 102 degrees or hotter temperatures.

Hollman described a two-pronged problem: the central plant could not deliver cooling system water at the optimum temperature and pressure, and the plant could not meet the demand for cooling water.

"Our core system and flow rates went totally out of whack," Hollman said.

He explained that the central plant sends cool water to air conditioning units in various buildings. The return water, after giving up its chill, goes into a thermal energy storage tank — and electric chillers work overnight to lower the temperature of the water, so it can do its chilling work again the next day.

But, with the return water running warmer than usual, and with nighttime temperatures in the upper 60s to upper 70s, the system never cooled down adequately, Hollman said. He noted the 77-degree "low" temperature the night of July 22. The next day, the heat wave peaked at 113.

That was Sunday the 23rd — when Hollman and his staff shut off the air conditioning in the ARC and the Pavilion, the campus's major recreation centers. This had happened once before during the heat wave, on July 20, for about two hours right before the 9 p.m. closing time.

The shutdown on the 23rd lasted from about midday until 5 the next morning. John Campbell, director of Campus Recreation, said the temperature in the downstairs weight room hit 97 degrees in late afternoon, while the temperature on the main floor hovered around 90. He said attendance on a normal weekend day in summer is 2,500 to 3,000, but on this day that number declined by half.

"The majority of our users completely understood the campus was in an extreme situation," Campbell said. He said his staff kept a close watch on clients to check for heat-related illness, and none was reported.

University officials said they were well aware before the heat wave that the cooling system needed help. A $22.8 million upgrade project is already in the budget pipeline, with a request for state money starting in 2008-09.

However, the campus hopes to get a head start, said Rick Keller, assistant vice chancellor for capital resource management. He said he and his staff are preparing to go to the UC Office of the President this month with a $7.5 million proposal to replace 40 percent of the campus's existing chilling system — parts of which are more than 30 years old.

At the same time, the university continues to expand capacity to handle the cooling needs of new buildings. Keller described a $7 million project, now under construction, to make the thermal energy storage tank twice as effective. To do this, the university is doubling the capacity of the electric chilling system that lowers the tank temperature.