Abstract

The extreme climate and remoteness of Inuit communities bring unique challenges to sustainable living. Homelessness and housing shortages are still common, underlining the need for the construction of durable, sustainable, and affordable housing. The building envelope is highly susceptible to moisture damage and deterioration if not well designed and constructed, especially in the Arctic. This thesis focuses on the heat, air, and moisture performance of structural insulated panels (SIPs) and attics in Arctic climates.
A full-scale SIP test hut with an attic is constructed in an environmental chamber. Eight types of SIP joints were monitored with thermocouples, with at least 6 thermocouples per joint. The SIPs were subjected to temperature differences of up to 62 ºC and pressure differences up to 15 Pa. The attic of the test hut is divided into two bays, one is unvented and the other is ventilated mechanically. Imposed external temperature conditions reflect typical conditions observed in Inuit communities, and small pumps are used to deliver controlled rates of air leakage from the indoor space to the attics. The attic bays are monitored with temperature, relative humidity, and moisture content sensors.
Using hygrothermal simulation software WUFI Plus, a model is developed and verified with the experimental results. The model is then used to simulate the performance of attics utilizing various ventilation strategies, including unvented and novel building integrated photovoltaic/thermal system (BIPV/T) ventilation methods, subjected to climatic conditions of three Inuit communities. The BIPV/T system uses solar energy to generate electricity while preheating outdoor air for attic ventilation. Various rates of air leakage are applied to examine the sensitivity of the attics under each ventilation strategy. Mold index is used to evaluate the long-term performance and suitability of each strategy.
It is found that while SIPs can be insulating and airtight, they are most susceptible to air leakage and moisture damage at the joints since they rely heavily on adhesive tape to prevent air movement. Complex joints where three panels meet are more leaky than joints where two panels meet. These joints are also more difficult to seal with tape. Joints above the neutral pressure plane are especially vulnerable to moisture damage since indoor air tends to exfiltrate through those joints.
Attics in Arctic climates can avoid mold growth with ventilation rates as low as 1 ACH, whether provided naturally or mechanically. Unvented attics are risky, though they can perform well if air leakage rates are kept within passive house standards. Also, diffusion vents improve the performance of unvented attics significantly. BIPV/T mechanical ventilation can dramatically improve attic hygrothermal performance while generating useful electrical and thermal energy, even at very high latitudes.