Canada is warming at double the rate of the global average caused in part to a fast-growing population and large land transformations, where urban surfaces contribute significantly to the urban heat island (UHI) phenomenon. The federal government released the strengthened climate plan in 2020, which emphasizes using nature-based solutions (NBSs) to combat the effects of UHI phenomenon. Here, the effects of two NBSs techniques are reviewed and analysed: increasing surface greenery/vegetation (ISG) and increasing surface reflectivity (ISR). Policymakers have the challenge of selecting appropriate NBSs to meet a wide range of objectives within the urban environment and Canadian-specific knowledge of how NBSs can perform at various scales is lacking. As such, this state-of-the-art review intends to provide a snapshot of the current understanding of the benefits and risks associated with the implantation of NBSs in urban spaces as well as a review of the current techniques used to model, and evaluate the potential effectiveness of UHI under evolving climate conditions. Thus, if NBSs are to be adopted to mitigate UHI effects and extreme summertime temperatures in Canadian municipalities, an integrated, comprehensive analysis of their contributions is needed. As such, developing methods to quantify and evaluate NBSs’ performance and tools for the effective implementation of NBSs are required.
When bringing a structure up to current building standards, or voluntarily constructing to higher insulating levels, adjustments to the thickness of walls may be required. To meet the energy and space saving requirements of today's building market, builders are looking for new materials and practices to insulate their walls. Vacuum insulation panels (VIP) have shown potential to meet or exceed today's high insulating levels while keeping the thickness of the building envelope down. One of the problems facing owners and builders wanting to use VIPs, is their unknown service life. As such, recent research has focused on developing methods to accelerate ageing in order to determine the service life of VIPs. However, a disconnect exists between results obtained from accelerated ageing and real time degradation. The process outlined within this thesis presents a method to link the results obtained from accelerated ageing with real degradation. In addition, the thesis presents the design, construction and commissioning of a new guarded-hot-plate testing apparatus to evaluate the thermal resistance of the VIPs as they are artificially aged. The latter focuses on the moisture accumulation and thermal resistance of climate aged panels. The rate of moisture accumulation in the VIPs located in the climate chambers can be determined when comparing to climate profiles of VIP walls that were found in-situ. To study the effect of moisture on the thermal performance of VIPs, VIPs from two manufacturers were held in a climate chamber at 30℃ and 90% RH for 30 days. The panels from the first manufacturer experienced a 0.2% mass increase from an initial mass of 840 g due to moisture and experienced a decrease of 5% in thermal resistance. The panels from the second manufacturer experienced a decrease of 6.5% in thermal resistance from a 0.05% gain in mass from an initial 246 g, proving that 1 2 3 132 4 5 6 7 8 9
Typical analyses of heat transfer across building envelopes consist of determining the thermal resistance of the assembly. The thermal resistance, or R value, is determined through test methods, calculation methods, or numerical simulations. In complex or novel wall assembly configurations, thermal resistance is required to be determined with experiments that use a guarded hot box (GHB) test apparatus according to ASTM C1363, Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus. One scenario in which complex heat transfer occurs is in a furred airspace in contact with a low emissivity, as the combined effects of natural convection and radiation dominate the heat transfer across the space. Convection and radiation heat‐transfer effects are much more sensitive to the variation in surface temperatures, orientation, and aspect ratio of the airspace. This paper presents the results of ASTM C1363 GHB tests of a full‐scale (8 ft by 8 ft [2.44 m by 2.44 m]) wall assembly containing a furred airspace, with one surface having low emissivity in two configurations. The first configuration is with ¾‐in. (19‐mm)‐depth strapping oriented vertically and spaced at 24 in. (0.61 m.) on center, creating four identical furred airspace cavities approximately 8 ft high by 24 in. wide. The second configuration consists of rotating the same wall assembly by 90°, creating four identical horizontally oriented furred airspace cavities. Each configuration was tested for three exterior temperature conditions: −20°C, −25°C, and −30°C—all with an indoor temperature of 21°C. Additionally, the experimental results were compared with results of the ISO 6946 Annex B.2 calculation method. The results from the tests did not show a significant difference in thermal resistance results between either the exterior temperature differences or when comparing the effects of airspace orientation. This highlights some of the challenges when trying to differentiate small differences between wall assemblies with GHB testing, especially when the experimental uncertainty is considered.
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