Brady — a mechanical contracting company based in Greensboro, NC — recently completed a wide range of mechanical system improvements and humidification upgrades to the North Carolina Museum of Art's East Building. Thanks to those improvements, the Norman Rockwell exhibition, American Chronicles, went on as planned from November 2010 to January 2011.
Reliability and indoor environmental control were the main concerns of the museum operators. Temperature and humidity fluctuations are the enemies of fine art, and these control issues were causing canvases to expand and contract, leading to premature aging. The museum was experiencing fluctuations of 30% humidity in the winter and up to 60% in the summer.
The project included HVAC system and technology improvements that promised to deliver ASHRAE Class AA environmental conditions and more than 57% energy savings. Since the project's completion, temperature and humidity fluctuations have been reduced to less than 5%.
In addition to the art preservation benefits, the upgrade has already produced $2.1 million in utility and maintenance savings during the past three years, exceeding performance contract projections.
Several innovative HVAC technologies and systems approaches were incorporated in the Museum project. These technologies include:
- Installation of a dedicated outside air unit to pre-treat, measure and control the airflow and dewpoint of the outside air to all four main air handling units.
- A high pressure, high purity cold fog humidification system to add humidity to the pre-treated outside air and to eliminate the need for a steam system. The cold fog humidification system was used for the single point dedicated outside air system. Since steam was no longer used, the steam system was removed from the facility.
Tim Gasper, P.E., told ContractingBusiness.com that by using the cold fog system, he and his team eliminated 94 individual steam humidifiers in the ductwork, as well as 94 control valves, sensors, and steam traps.
"We determined that since humidity and temperature must be the same at all locations, let's put humidification control at one point; and that point is where the outside air enters the facility. We do all humidification there. Then, we send humidified air to all existing air handling units through an existing underground tunnel. It simplified the humidification greatly," Gasper says.
Other improvements included a variable speed high Delta T chiller plant; refrigerant-free cooling; and chiller/tower optimization control.
"This was the most inefficient system I had seen in quite awhile," recalls Gasper. "They've been hamstrung for years by budget issues that didn't allow them to spend the kind of dollars they needed to properly maintain the system. Their annual energy costs were $6 per square foot. BTU usage was about 300,000 per sq. ft. There were plenty of opportunities for efficiency gains. The chillers were running at full capacity in winter, when it was 0F outside, and the boilers were running full flood as well. They weren't able to maintain temperature and humidity conditions anywhere near what they were supposed to for museum operations. So the opportunity was there," Gasper explains.
Maintaining proper conditions for art preservation requires that the museum's conditions be maintained around the clock.
"There were no opportunities to save energy from temperature setbacks; we achieved the savings strictly from efficiency," Gasper says. "We saw 57% BTUH savings based on more efficient equipment. There was so much savings opportunity that we could afford to retrofit just about every system in the facility. However, we didn't replace the main air handling units; there, we just replaced the bearings and put the speed drives on the existing fans."
The upgrades ensured the display of other major exhibits over the past few years, including works by Monet and an exhibition of Egyptian art, says Larry Wheeler, director for the North Carolina Museum of Art.
Products used for the project include a Trane CenTraVac® chiller and Patterson-Kelley boilers.
In April, Brady reported the independently audited, annual energy savings to the State of North Carolina. For the third year, actual energy savings have exceeded performance contract projections. The $50,000 per month average savings reflects a 60% reduction in utility expenses for the museum.
This is the state's first capital improvement project funded by guaranteed energy savings. Facility upgrades to the East Building began in 2005 and were completed in January 2007. The performance contract guarantee is for 12-year savings totaling more than $6 million in utility and maintenance costs. The project has received a regional ASHRAE award, and has been submitted for national ASHRAE award consideration.
Brady operates offices in Greensboro, Raleigh, Fayetteville, Wilmington, and Charlotte. Founded in 1962 by Chairman Don Brady, the family-owned company employs approximately 300 people.