The Perfect Prescription for Drying: A Case Study
July 13, 2007
PCL Constructors Westcoast, Inc., a Canadian general contractor, is the design/build partner for the construction of the 645,000-square foot, five-story Abbotsford Regional Hospital and Cancer Centre in Abbotsford, B.C. Built on 30 acres of land, the high-profile, $355-million project is the first major public-private partnership initiative in the British Columbia health care sector.
Set to be completed in May 2008, the Abbotsford Regional Hospital will house the first cancer treatment center fully integrated into a British Columbia hospital, and is Canada’s first full-scale hospital built to environmentally friendly LEED Silver Standards. The 300-bed facility will showcase a unique design capable of redefining today’s modern regional hospital with amenities that include a healing garden for patient and families, public areas in a four-story glass atrium, and rooms that look out onto gardens.
Completing the unique construction on time required a key component – precise humidity and temperature control during the interior finishing stage. Rob Ireland, PCL general superintendent, and Daryl Campbell, one of PCL’s area superintendents for the development, sought a desiccant drying solution that would produce overnight drywall drying times, eliminate delays in laying flooring systems over concrete and provide acceptable conditions for workers – all to ensure weather and climate did not contribute to construction down time.
“On a project of this scale, the construction schedule is critical,” Campbell said. “Plus, our firm had a financial stake in meeting the completion date.”
Because the company had provided successful construction drying services for previous PCL projects, Gregg Lowes, industrial accounts manager for Munters Moisture Control Services (MCS) in Western Canada, approached PCL site personnel to offer assistance on the Abbotsford hospital project.
Formulating a Strategic Drying PlanWorking with PCL, Munters helped develop a strategic plan that called for deploying high capacity desiccant dehumidifiers on the hospital’s rooftop, and delivering the conditioned dry air through the facility’s mechanical exhaust ventilation system.
This plan ensured comprehensive air distribution throughout the structure, without affecting the supply or return ductwork on the permanent HVAC system. As an added benefit, the design would not require messy and labor intensive propane heaters, or temporary ducting or heating lines that could potentially obstruct the 450 construction personnel working inside and outside the facility.
The size and scope of the project also gave Munters the opportunity to unveil a the new DHI-125-ESU, a 9,000-CFM system that operates on both natural gas and electric power.
“The DHI-125-ESU dehumidifier is our most technologically-advanced and highest capacity rental dehumidifier developed to date,” Lowes said. “The unit is specifically designed for large scale projects and is extremely energy efficient for its size.”
Munters personnel worked with Ireland to configure the Munters system to meet the design loads specified by PCL for the project. This involved a number of possible scenarios and working closely with the PCL team to find the right combination of targeted parameters that were both effective and budget sensitive.
Nine DHI-125 units were delivered to the construction site in November 2006 during the interior finishing and drywall installation stages of the project.
The dehumidification systems, coupled with several heaters, made up the equipment used to provide temporary climate control. A 100-ton crane hoisted all of the equipment onto the facility’s roof.
“Gregg was very thorough with the pre-planning and installation of the units,” Ireland said.
Holding Conditions Through Harsh, Humid WeatherDuring most of the construction period, the Abbotsford area experienced harsh fall and winter weather. It began with torrential, record-breaking rainfall in November followed by cold and gale force windstorms in December. In January and February, the area experienced substantial snowfall and periods of cold winter temperatures, with chill factors reaching minus-4 F over a few weeks.
“The amount of precipitation and inclement weather created sustained high humidity in the area, with levels often reaching 95 percent for days at a time,” Ireland said.
The equipment held steady, maintaining both workable interior conditions as well as providing proportionate drying functions throughout the project.
“We were very impressed that the construction process was not delayed due to the extremely wet, humid and cold weather we experienced during those few months,” Ireland said. “While production personnel working outside were dressed in parkas, those handling indoor tasks such as drywall finishing wore t-shirts.”
Throughout the project, Munters technicians monitored the nine systems in order to maintain interior conditions at 22 to 24 percent relative humidity and a temperature of 65 to 68 degrees F – the parameters set by PCL.
In addition to controlling indoor conditions, the equipment facilitated the quick drying of compound mud for the walls, drywall and other building materials, and protected water pipes during the cold winter.
“An additional benefit to the workers, there was no evidence inside the building of any heating or drying equipment, heating lines or ductwork that could obstruct their work,” Ireland said.
All Munters units were removed in April when the building could rely on its own HVAC system to control the indoor environment.
According to Ireland, the partnership was the perfect prescription. “Using this equipment helped us meet deadlines and keep the project on track,” he said. “There’s no way we would have been able to maintain conditions and keep on schedule.”