Koury Corporation owns and manages more than 1.3 million sq ft of office and industrial properties in the Greensboro, NC area. A fully integrated real estate, construction, and management organization with over 1,400 employees in architectural, engineering, construction, and facilities management, the company's tenants include names like Bellsouth, AT&T Wireless, Coca-Cola, Dover Elevator, Dun & Bradstreet, and Serta.

Koury's vice president of facilities management, Gene Greer, is responsible for the maintenance of all the company's properties with the primary goal of reducing operating costs. He wanted to keep the company's tenants comfortable and also reduce service calls, and he decided to try thermally powered VAV diffusers. After using them in several buildings, he also found that they drastically reduced service calls. Now, his data for the last three years confirms lower HVAC maintenance costs of more than 20% for a building with thermally powered VAV diffusers over a similar building with part constant volume and part VAV box systems.

One VAV Box For Five Offices Didn't Add Up

Koury had been experiencing problems in a 90,000-sq-ft office building with a major tenant. One thermostat controlled a VAV box for five offices and as a result, only one person was comfortable at time. He tried using VAV diffusers and decided that they worked quite well.

Comfortable tenants are important to the goal of low operating costs. When tenants are not comfortable, the maintenance staff must spend time resolving their complaints. Thermally powered VAV diffusers can help because each is a zone of temperature control with a built-in thermostat and damper to vary incoming airflow. Comfort is further enhanced by the even temperature distribution and room air movement due to the almost constant discharge velocity of the VAV diffusers. Maintenance for repair and recalibration is also reduced due to the durability and dependability of the aerospace wax motor thermostat/actuator.

Some Persuasion Necessary

When Greer decided to use VAV diffusers in other buildings, he still had to convince Koury's engineers and contractors. They had no experience with VAV diffusers and a typical claim was, "They do not work." However, Greer knew they worked because he had tried them. Next was the claim that VAV diffusers cost much more than standard air diffusers. However, when an actual first cost comparison was made it was clear that the installed cost of VAV diffusers was comparable to conventional VAV systems. "I had to be very persistent with our engineers and contractors to get Acutherm's Therma-Fuser diffusers installed," Greer said. The result is that eight Class A office buildings with a total of 443,465 sq ft are now conditioned with over 1,000 VAV diffusers.

Using interoperable VAV diffusers that tie in with a BMS and allow his maintenance staff to monitor and reset the temperature without going into the room, was also part of the successful system. Greer has had about 200 interoperable VAV diffusers installed in two buildings, totaling 77,964 sq ft, "With Therma-Fuser diffusers, we can keep all of our tenants happy and give them individual control," he said.

According to Greer, Koury's major tenant complaints have always been HVAC comfort and roof leaks. VAV diffusers haven't resolved any roof leaks, but they have reduced HVAC complaints. "In two years, we have had a grand total of three calls regarding Therma-Fuser diffusers," Gene said.

The Savings

According to Greer, actual data taken over the past three years shows over 20% lower HVAC maintenance costs for a building using VAV diffusers compared to a building with part constant volume and part VAV boxes. He collected and compared data from two Greensboro office buildings, which are almost the same size. The Brookhollow Plaza building has 91,000 sq ft on four and a half floors with air distribution that is part constant volume and part VAV boxes. The 84,000-sq-ft, 3-floor Grandover Office Building relies solely on VAV dif-fusers.

HVAC maintenance costs for the Grandover Office Building with VAV diffusers were 26% lower in 2002, 21% lower in 2003, and 22% lower in 2004. Electric utility costs for the same all-VAV diffusers building were also lower in each year.

Even though the lower operating costs of VAV diffusers are impressive, Greer emphasized that the comfort they provide is still most important. "We all have to make money. That is the name of the game. But if we do not have tenants, low operating cost won't help," he said.ES