This humidity control unit from Munters was brought in during the construction of Target Field, home of the Minneapolis Twins. The unit, serviced by Joe Schmitz, helped to take humidity out of spaces where custom millwork was being installed.  Article images courtesy of Munters Moisture Control Services.

In a few weeks, the Minnesota Twins will be catching fly balls in Minneapolis’ Target Field, a $425 million ballpark in the city’s historic warehouse district. Construction on the 1 million-square-foot park started in August 2007, and ended in December 2009 - two months ahead of schedule.

The new park, named after the well-known discount retailer, has a number of highlights, including the return of an open-air stadium to the Twin Cities. For the past several years, the Twins have played at the 27-year-old Metrodome, a covered stadium in Minneapolis named after former U.S. Vice President Hubert Humphrey. Now when a player “hits one out of the park,” the ball really will leave the stadium.

Target Field also has a touch of sophistication with the addition of ornate millwork. Many of the clubs, restaurants and locker rooms in the stadium feature cabinetry with high-end finishes. But in order for the millwork to last through the humid summer during construction, engineers needed to introduce temporary dehumidification. That’s when Munters Corp. was brought in as a “pinch hitter.”

Munters technician Schmitz with a 6,000-cfm humidity control unit from Munters. The unit was used to dehumidify portions of Target Field in Minneapolis.


Minneapolis-based M.A. Mortenson Co. was responsible for making the new open-air field a reality. The company has had plenty of past experience with sports facilities, including work on the Xcel Energy Center in St. Paul, Minn., and the Pepsi Center in Denver.

Officials from M.A. Mortenson are hoping that Target Field will be one of the most environmentally responsible ballparks when it opens its doors to fans in April. The U.S. Green Building Council is planning to review Target Field for Leadership in Energy and Environmental Design certification.

But besides sustainability, the stadium owners want the ballpark to look polished and pleasing. Executive suites in the stadium, along with lounges, clubs and locker rooms all have custom millwork, which needed special handling from M.A. Mortenson workers.

“The manufacturer had specifications for temperature and humidity for the wide variety of wood and laminate being installed,” said Eric Keleny, the mechanical, electrical and plumbing coordinator for M.A. Mortenson. “Extremes in the indoor environment could potentially expand or shrink the wood, causing warping.”

To protect the wood from warm weather and high humidity, Keleny contacted Munters Moisture Control Services for a solution. He said that relative humidity levels indoors needed to remain below 50 percent while temperatures needed to stay below 80°F.

John Pfeffer, industrial accounts manager for Munters, suggested using three of the company’s 6,000-cubic-feet-per-minute humidity control units along with several blowers.

“The HCU is capable of delivering dew points as low as 40ºF in even the highest humidity-load conditions,” Pfeffer said. “Because the unit utilizes reactivation energy, it uses less energy while providing comfortable outlet temperatures.”

The unit combines cooling and desiccant dehumidification in one system in order to control dew-point temperatures in hot and humid climates. Munters says the system is ideal for temporary humidity control during building construction projects like the Target Field project.

Joe Schmitz checks the performance of the HCU with a meter that measures humidity and temperature. Schmitz will compare the reading he gets from the unit to the ambient conditions to determine how well the unit is operating.


When the units arrived, putting them in place was not an easy task. In fact, using the ballpark’s inner field to reach the indoor spaces was impossible. To remedy the situation, the units were placed in different areas of the main concourse and were equipped with flexible duct. The duct was then led to the areas of the stadium that needed the dehumidification.

Twelve 48-inch turbo fans moved air through the flexible duct and into the spaces requiring humidity control.

“We moved quickly to make sure indoor spaces were conditioned as millwork was installed in bar areas, administration offices, board rooms, executive and corporate suites and throughout locker room areas,” Pfeffer said.

The Munters units were able to condition 150,000 square feet of the park’s 500,000 square foot of non-stadium areas. Technicians monitored the conditions of the spaces and checked to make sure the unit was running on a regular basis. This included changing filters as needed.

Officials with M.A. Mortenson said the dehumidifiers did more than just protect the valuable millwork. It also kept workers comfortable during warm summer months. In fact, the company said that the comfortable working environment made it possible for Target Field to be completed ahead of schedule.

“Munters stepped up to the plate to keep the high-end millwork safe from high humidity levels during hot and humid summer and fall months, while keeping our workers comfortable,” Keleny said. “We are very pleased with the performance of the units, their easy installation and the monitoring by Munters technicians.”

As Target Field and M.A. Mortenson wait to see if the USGBC will grant LEED certification to the park, officials know that they captured LEED points by using the humidity control units. The units were used along with the permanent HVAC systems to flush out the building prior to occupancy, a guideline which LEED requests.

When baseball fans come out in April for the first pitch at Target Field, they can be assured they are sitting in a sustainable baseball stadium.