CONDENSATION RESEARCH condensed ahead of windows (often the least-insulating envelope component). Furthermore, though 10°C outdoor temperature is not beach weather, it’s also far from extreme cold. Per VBBL, Vancouver’s winter design temperatures range from -6 to -8°C. Given this unit’s findings and its implica- tions for our own projects, we leveraged Stantec’s research funding to conduct further analysis. 5 FINITE ELEMENT ANALYSIS (FEA) Based on as-built drawings and site investigation of the unit, Stantec created an FEA model to analyze 1) the unit’s response to colder outdoor temperatures, and 2) whether envelope modifications can keep indoor surfaces above the dew point. The FEA model captures the unit’s exterior walls constructed with 2x6 wood- framing, cavity insulation and three-in. exterior mineral wool. The bedroom vinyl window is triple-glazed and the floor insulation is rated at R-20. Per its draw- ings, the building was subject to Green Buildings Policy for Rezonings, estab- lishing an energy model target of TEDI ≤ 15 kWh/m2/yr (Step Code 4 equivalent), which resulted in more-insulating features like three-pane windows and mineral wool. Aside from the concrete balconies/projec- tions, other concrete elements are also in proximity to the bedroom (Figure 6). 5.1 SIMULATION 1 – CALIBRATION To calibrate the FEA model, our first run was based on 10°C outdoors and 23°C indoors (matching field data). This produced 15.5°C in the wall corner (Figure 7), correlating closely with 14-15°C field measurements. The margin of error is likely from numerous sources – as-built vs. modelled insulation, equip- ment calibration, wind chill, etc. (For visual clarity, the FEA model’s isotherms are greyed out when above a certain temperature.) 5.2 SIMULATION 2 – WINTER AVERAGE Next, we reduced outdoor to 2°C, representing Vancouver’s average daily winter low, yet warmer than VBBL’s design temperatures. Indoor was reduced to 21°C to mimic variations in preferred temperatures. This produced 11°C in the wall corner (Figure 8), colder than the 13.7°C dew point temperature from the field investigation. Notice how Figure 8’s cold flooring colours (along the wall) resembles Figure 1’s condensation extent. 5.3 SIMULATION 3 – INSULATION In reviewing the FEA model’s geometry, we wondered if well-intentioned energy bylaws created better envelope assemblies, but also inadvertently “funnelled” heat into remaining paths of least insulation? To test this hypothesis, we maintained the 2°C outdoor temperature and the 21°C indoor temperature but removed the exte- rior walls’ mineral wool insulation. This produced 9.5°C in the wall corner (colder than the 11°C from the previous run) and enlarged the floor’s “cold zone” (Figure 9). Our hypothesis appeared disproved, at least for this building geometry. 6 NEXT STEPS In our presented FEA simulations, provided indoor conditions that meet BC Housing’s winter guidelines, the floor temperatures remain near or below the dew point, which – alongside flooring condensation – highlights how impactful uninsulated concrete can be. We also showcased the strength of 3D FEA by capturing this unit’s complex geometry (Figure 6) – a task not achievable with 2D modelling tools. Future simulations may showcase wall insulation changes, two-pane windows, structural thermal breaks and corresponding indoor conditioning requirements. Ultimately, the goals of this ongoing research are to gain insight on managing condensation in existing buildings and to develop insulation best practices in new construction. If you’re interested in hearing more about or supporting this research, please email: van.buildingscience@stantec.com. FIGURE 7: MODEL WITH AN OUTDOOR TEMPERATURE OF 10°C AND AN INDOOR TEMPERATURE OF 23°C. FIGURE 8: MODEL WITH AN OUTDOOR TEMPERATURE OF 2°C AND AN INDOOR TEMPERATURE OF 21°C. FIGURE 9: MODEL WITH AN OUTDOOR TEMPERATURE OF 2°C AND AN INDOOR TEMPERATURE OF 21°C WITH NO MINERAL WOOL. SPRING/SUMMER 2026 15
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