Managing Moisture at Mass Timber Student Housing Project

The University of the Fraser Valley (UFV) in British Columbia is expanding its Abbotsford Campus with several buildings including student housing. Clark Builders, a division of Turner Construction, is leading the construction of the 400-bed six-storey residence set to open in 2025. The 149,400 square foot hybrid structure is comprised of reinforced concrete, mass timber, and light wood framing. The UFV Integrated Project Delivery (IPD) team was keen to incorporate a multi-faceted humidity control system into the temporary heating plan to ensure optimal conditions were maintained for the light wood framing and cross-laminated timber (CLT) floor system throughout the winter months.

Article by Polygon Restoration

Challenge

Clark Builders went to work assembling the pieces of the temporary heating system that could respond to the humid climate of British Columbia (BC). Micah Robinson, a Superintendent at the UFV project recalls how important climate control and moisture content monitoring would be for the success of the project. “We needed to control the ambient conditions throughout multiple stages of the project. The project team understood the importance of maintaining moisture content for the wood below the 19% threshold.”

Micah and his team identified 10 locations on each CLT floor plate to take moisture readings of the CLT floor panels. “If we did it manually it would take someone about a half day each week.” A person would need to traverse the “E” shaped building, taking readings and inputting data in a spreadsheet. Robinson suspected there would be little time left to do thorough analysis of the wood moisture levels and someone on the team would have to scan the values. Identifying potential issues would be slow and so would the fixes. “It seemed so wasteful to just take our own readings. We looked at three different providers during the planning phases and decided that Polygon Climate Control was right for the UFV Student Housing project.”

The Polygon Climate Control Vancouver office worked with the UFV IPD team on technical requirements, logistical considerations, and equipment options. They planned for the following:

• the CLT being exposed to large amounts of rain and water. Varied timings of when floors would be closed up;
• high building density and an E-shape design that could trap moisture and make building air delivery more complex. Wide open spaces are simpler and faster to treat and control;
• a site within an operational university campus with limited physical space; and
• requirements to monitor and record energy usage.

Solution

After conducting a thorough moisture load analysis, the Polygon Climate Control team proposed and installed an integrated solution made up of ambient and wood moisture sensors that could inform control of desiccant dehumidifiers with in-line heat. Hybrid fuel units with gas-fired heaters were chosen for space, energy, and effectiveness. Operation technicians placed over 50 sensors, 10 per floor, to constantly monitor conditions of the air and the CLT. An average of critical zones and floors were available inside the user platform. This gave the project team visual indicators for rapid decision-making and constant oversight but also enabled automation of the climate control equipment, saving time in managing conditions and avoiding energy waste. The UFV IPD team easily moved sensors to new floors as work progressed. Allowing them to adapt to the solution when and where it was needed most.

“I understood what the Polygon team were saying about using DH (desiccant dehumidification) instead of just heat to control the moisture. It was very noticeable once it was turned on compared to heat alone—it worked so well. And with the sensors measuring everything, the system was a set-it-and-forget-it approach.” In addition, the duct work was simpler than Robinson imagined. “It was light weight, out of the way, and easy to manage. “I thought we would be tripping on duct work all day long. Instead, when we need to work on something we would just untie the secure string, do our work, and place it back.”

The data helped the UFV IPD team make decisions along the way. Fluctuations in weather conditions and temperature could be quickly addressed. At one point during an unseasonably cold period, the team identified that building temperatures were too low based on dashboard readings, so a supplemental head was added. At another point, Polygon was requested to remotely adjust the target temperature from 20 degrees Celsius to 15 degrees Celsius, to maintain appropriate working temperatures and ensure energy optimization.

During fluctuations of installation durations and sequencing of light wood framing and CLT floor plates, Robinson was able to watch the ExactAire dashboard to see how each floor or zone was progressing. It informed daily micro decisions about what areas to focus on, for how long, and to what degree. This freed up labour and time to work on other things and gave the team the information needed to report back to everyone involved.

“It was great that we were able to be conscientious of energy consumption. Polygon was able to give us some electric equipment and add automatic climate control features to the system.” This meant the equipment did not need to run unnecessarily and waste energy.

_{Figure 1. Ambient humidity levels on Level 3 in November}

“I liked watching the moisture content levels going down well below our specifications. They went from 18 to 15 and in some areas down to 10%, slow and steady.”

_{Figure 2. Wood moisture content (WMC) levels from multiple levels mid-November to mid-December}

_{Figure 3. The IPD Team’s project progress report showcases how the Polygon Climate Control equipment and sensors are providing ongoing insight and protection of the building.}

Benefits

• Humidity Control: A reliable, flexible and robust addition to a moisture mitigation plan
• Increased Efficiencies: A fully integrated system helped eliminate manual readings, expedited climate control related activities and reduced energy consumption
• Stakeholder Confidence: Dashboards of the conditions were shared in reports to stakeholders giving them the reassurance that their assets were being well-managed and protected.

 “Working with Polygon was great. It felt like an organic collaboration, and they made things easy. I would use this system on other mass timber projects facing similar potential moisture challenges.”

To learn more about how to monitor moisture content, visit Wood and Concrete Moisture Management.