Since many buildings in Canada were built prior to the advent of national and provincial energy codes and standards, quantifying building envelope thermal performance in existing buildings is an important step in identifying retrofit opportunities. Due to the lack of building codes or standards for existing buildings in Canada, development of a rapid and robust quantitative approach to evaluate and rank buildings for vertical envelope retrofits is required. Hence, this dissertation sought to develop quantitative approaches to evaluate existing building envelope thermal performance in Canada and beyond. Following current professional practices, in Chapter 1, a comprehensive study was conducted on 49 campus buildings at the University of Victoria (UVic) to evaluate potential energy savings from vertical envelope retrofits, and to further validate those savings through more detailed energy models and parametric analyses for a subset of buildings. To this end, the thermal performance of a building envelope was quantified based on its heat loss coefficient (UA), obtained from multiplying its surface area (A) by its thermal transmittance (U-value). Heat loss calculations were used as a metric to inform envelope rehabilitation prioritization, while considering other data such as age and physical condition in parallel. Archetype energy models for selected buildings were used to evaluate the impacts of envelope retrofits on energy and GHG savings. The outcomes of this study allowed the University to weigh the benefits of improved energy performance from envelope retrofits against associated capital cost expenditures. Also, the implemented methodology and studied parameters unveiled a new horizon in evaluating the thermal performance of existing building envelopes in Canada, where a building code for existing buildings has not yet been established. Considering the economic findings of the envelope retrofits studied, it was concluded that in the absence of an existing building energy code, the University would likely require additional incentives, such as higher utility costs, higher carbon taxes, or qualifying for utility incentive programs to justify improving existing building envelope performance on the basis of energy only. The strength of the proposed methodology in Chapter 1 was in its balance of effort and ultimate decision-making utility, where reasonable thermal bridging approximations based on simulation models for existing buildings can yield data accurate enough to inform a ranking exercise on a large breadth of subject buildings. However, since numerical models do not consider degradation of building materials, real moisture content, and errors associated with manufacturing and installation, actual building envelope thermal performance differs from 3D simulation models. To study this limitation, in-situ thermal assessments of building envelopes were performed to quantify their actual thermal performances. To this end, Chapters 2 to 4 of this dissertation attempted to determine the viability of an external infrared thermography (IRT) survey technique for quantification of heat losses through the opaque building envelope, and also explores its potential application in identifying and comparing sources of air leakage. The experiments were performed on wood-framed wall assemblies commonly used in Canada due to growing interest among designers, builders, and governments to encourage the use of wood as a building material. In these studies, (Chapter 2 to Chapter 4), thermal transmittances (U-values) of wall assemblies were estimated with external IRT and compared with 3D computer simulations. Furthermore, the impact of the accuracy of U-values estimated with IRT on the deviation of energy simulation outputs with metered data was examined. Finally, a novel relative quantitative infrared index (IRI) was proposed as a means to facilitate rapid evaluation and subsequent ranking of building envelope thermal performance. From the experiments in Chapters 2 & 3, it was found that the U-values obtained with IRT were comparable with simulated values suggesting IRT can be a reliable tool for estimating the thermal performance of wood-framed wall assemblies. Results also demonstrated that thermal imaging artefacts including nonlinear characteristics of infrared (IR) camera focal array, a.k.a. non-uniformity corrections (NUC) and vignetting could have a substantial influence on the accuracy of results, in particular energy model outputs. This limitation was resolved by introducing a practical approach where thermal images were taken from different incident angle. Overall, IRI was found to be a reliable metric for relative quantitative comparison of building envelope thermal performance regardless of boundary conditions. Moreover, outcomes of the IRT air leakage study in Chapter 4 indicated that combined qualitative and quantitative IRT approaches could potentially be implemented by practitioners to identify sources of air leakage and thermal bridges in buildings and compare their relative severity. Since blower door testing is gradually being introduced as a building code requirement to measure building envelope airtightness in an increasing number of Canadian jurisdictions, performing IRT simultaneously is potentially valuable exercise in this context. Ultimately, the methodologies outlined in Chapters 2 to 4 can help decision-makers to characterize building envelope retrofits from a performance perspective, and potentially serve as a basis for governments to develop policies to improve existing building energy performance. The methodologies in Chapters 2 to 4 prompted opportunities to utilize the emergent technology of small unmanned aerial vehicles (UAVs) equipped with an infrared camera for quick thermal assessments of building envelopes. The last chapter of this dissertation, Chapter 5, outlines advantages and limitations of aerial IRT (UAV-IRT) surveys compared to conventional stationary IRT. Furthermore, a set of best practices for UAV-IRT were presented to minimize dynamic measurement uncertainty. It was concluded that with the current IR camera technology, aerial surveys for quantitative thermal assessment of building envelope are not as accurate as with conventional infrared thermography; further investigations by manufacturers and researchers are recommended.

This book results from a Special Issue published in Energies, entitled “Building Thermal Envelope". Its intent is to identify emerging research areas within the field of building thermal envelope solutions and contribute to the increased use of more energy-efficient solutions in new and refurbished buildings. Its contents are organized in the following sections: Building envelope materials and systems envisaging indoor comfort and energy efficiency; Building thermal and energy modelling and simulation; Lab test procedures and methods of field measurement to assess the performance of materials and building solutions; Smart materials and renewable energy in building envelope; Adaptive and intelligent building envelope; and Integrated building envelope technologies for high performance buildings and cities.

Buildings, Thermal insulation, Thermal behaviour of structures, Thermal environment systems, Irregular, Infrared radiation, Detectors, Thermography, Temperature measurement, Thermal design of buildings, Cameras, Test equipment, Performance testing, Pattern recognition, Reports, Testing conditions, Control samples, Defects, Specimen preparation, Heat loss, Heat transfer

Building energy consumption accounts for about 40% of the total energy consumption in the U.S., and therefore approaches that can reduce building energy demand are of great interest. The building envelope system is one of the main elements in buildings that can be improved for better building energy performance, and it also plays a significant role in building energy simulation. The thermal resistance, i.e., the R-value, is the key thermal parameter for building envelope systems contributing to the whole building energy performance. While the R-value has been long introduced in the building science field, however, there is still a lack of sufficient research work in understanding its influence on the whole building energy simulation process and results. In particular, there is serious need for experimental methods to determine the real R-values for existing buildings in order to obtain the actual building performances instead of the theoretical values. The primary goal of this proposed research is to develop a quantitative infrared thermography approach to measure the R-values for building envelope systems on site. Achieving this would provide the industry with a more practical and faster alternative to measure the R-values for existing buildings. Traditionally, to measure the real R-value of building envelope systems, Hot Box Test Method is used in laboratory to measure building envelope mock-up assemblies. However, the Hot Box Test Method requires large testing facilities and also an envelope component to test, which will not be practical when measurements of existing buildings are of concern. Compared to new construction, for existing buildings, in-situ measurement of the building envelope thermal properties may be essential since in most cases drawings and details may not be known. The Heat Flow Meter Method is the generally known technique for in-situ measurement, which involves the use of a number of sensors and portable data acquisition systems. However, due to the unsteady natural conditions, the accuracy of Heat Flow Meter Method is not completely understood yet. To consider the influence of unsteady environmental conditions, some dynamic methods have been developed. The dynamic methods are so far not widely known or commonly used for in-situ measurement as their accuracies and performances are not completely explored. The infrared thermography has long been used for building diagnosis purposes to detect surface imperfections, moisture issues, air leakage and thermal bridge locations. Even though it has served as a powerful diagnosis tool for years, its application still remains qualitative and the interpretation of the image results can be somewhat confusing. However, the capability that infrared camera can catch the temperature distribution on the entire surface gives us the potential to use it as a quantitative tool for in-situ measurement of building envelope thermal properties. This research is focused on the development and validation of a quantitative methodology using infrared thermography for in-situ measurement. Several key difficulties, such as the exterior radiation and convection model, interpretation of infrared images and measurement of environmental conditions are discussed and explored. The results of this study can serve as a quick and effective tool for engineers and researchers to measure thermal properties of existing buildings, and therefore provide appropriate inputs for building energy simulation and energy retrofit.This research has been carried out through accomplishing several objectives. Initially, the influence of R-values for building envelope systems in the whole-building simulation process was studied, especially the detailed modelling approaches for several common techniques to improve the building envelope performance such as adding insulation materials and using advanced building envelope system types. This initial study helped better understand the importance of obtaining the realistic R-values instead of the design values. The next objective was to explore the existing methods to measure the building envelope R-values, using both the Hot Box Test Method and the Heat Flow Meter Method. By comparing the existing test methods and models, the most appropriate one can be used for on-site application to validate the results of infrared thermography method developed in this research. The final objective was to develop a quantitative infrared thermography testing method and calculation model that can be used for in-situ R-value measurement as a quick and practical tool.

Infrared thermography is an important and powerful technique for diagnostics and evaluation of building envelope, in terms of locating thermal bridges, damaged thermal insulation, air leakage, moisture damage, and cracks, all of which contribute to an increase in the energy consumption of the buildings. This is because typically the thermal gains or losses in practice are greater than those estimated during the design stage. Accurate and detailed information of where a problem occurs can reveal the source of the problem thus avoiding extensive renovation work and hence decreasing the cost of repair work and potential energy savings can be achieved. The present study is aimed at assessing the effective R-value of building envelope, using high definition thermal imaging technique.

The design and construction of the appropriate building envelope is one of the most effective ways for improving a building’s thermal performance. Thermal Inertia in Energy Efficient Building Envelopes provides the optimal solutions, tools and methods for designing the energy efficient envelopes that will reduce energy consumption and achieve thermal comfort and low environmental impact. Thermal Inertia in Energy Efficient Building Envelopes provides experimental data, technical solutions and methods for quantifying energy consumption and comfort levels, also considering dynamic strategies such as thermal inertia and natural ventilation. Several type of envelopes and their optimal solutions are covered, including retrofit of existing envelopes, new solutions, passive systems such as ventilated facades and solar walls. The discussion also considers various climates (mild or extreme) and seasons, building typology, mode of use of the internal environment, heating profiles and cross-ventilation Experimental investigations on real case studies, to explore in detail the behaviour of different envelopes Laboratory tests on existing insulation to quantify the actual performances Analytical simulations in dynamic conditions to extend the boundary conditions to other climates and usage profiles and to consider alternative insulation strategies Evaluation of solutions sustainability through the quantification of environmental and economic impacts with LCA analysis; including global cost comparison between the different scenarios Integrated evaluations between various aspects such as comfort, energy saving, and sustainability