The primary objective of this study was to investigate mould growth resistance of different types of wood products which include the sheathing and framing within full scale wall assemblies. Secondary objectives were to investigate the difference in mould growth resistance between borate-treated and untreated wood products as well as provide information about mould growth under different temperature and humidity conditions for treated and untreated wood products. <br /><br /> The objective of the study is to better understand mould growth, and to examine the effects of varying high moisture conditions on wooden products and the mould growth which may result. More importantly this will be examined on full scale wall assemblies; to date mould growth studies have only been performed within a laboratory on small samples of materials. Moreover, this study recreates the conditions which evidently cause mould growth on full scale wall assemblies. Tests were performed within a climate chamber on three full scale wall assemblies. The original scope of this study included an examination of the sheathing and framing components within a full scale wall assembly, however this study will focus mainly on the sheathing. <br /><br /> Results of this study indicate that the relative humidity conditions needed for mould growth on wood are higher than originally believed (i. e. , significantly greater than 80%RH). During the first eight weeks of test number one the relative humidity at the surface of the sheathing was held constant at 95% and little mould growth was observed on the untreated sheathing (mould growth index of 3 or less); little or no mould growth on the treated sheathing (mould growth index of 1 or less). The second and third tests demonstrated that the presence of liquid water greatly accelerated the time to germinations, the amount of mould growth (up to a mould growth index of 6), and the rate of mould growth. All three tests clearly showed that borate-treatment reduced the amount of mould growth; however, the concentration of borate-treatment, and the types of materials treated, does affect the resistance of mould growth. Furthermore, there was some evidence to suggest Borate treatments of the plywood increased the time to germination significantly, from a few weeks to 16 weeks in this study, but once mould growth was initiated, the rate of mould growth was similar to that of the untreated plywood. Two mathematical models to determine mould growth were examined: Viitanen and WUFIBIO (Sedlbauer). Viitanen?s model predicted time to germination and rate of growth rate well for untreated plywood, and WUFIBIO predicted time to germination but not the growth rate. It was also found both models err on the side of caution in predicting mould growth. <br /><br /> Recommendations include improvements to the test method and producers, and for future work.

Windows reduce heat loss and heat gain by resisting conduction, convection, and radiation using thermal breaks, low-emissivity films, and window gaps. Contrary to advancing these resistive qualities, this research introduced a highly conductive gap medium using Al2O3 nanoparticles dispersed in deionized water to enhance thermal conductivity. The solution harnessed the photothermal properties of Al2O3 nanofluids to trap, store, and transport thermally charged fluids to heat exchangers to preheat air and water, and to generate electricity forming a transparent generator—the Nanowindow. Seven Nanowindow prototypes with varying orders of air and fluid columns were fabricated and tested using distilled water (H2Owindows) to establish a baseline of performance. A solar simulator was built to avoid environmental radiant flux irregularities providing a uniform test condition averaging 750–850 W/m2, and resulted in an undefined spectral match, Class B spatial uniformity, and Class B temporal stability. All Nanowindows were tested in a calibrated hot box determined to have a ±4% degree of accuracy based on four laboratory samples establishing a framework to conduct U-factor and solar heat gain coefficient (SHGC) measurements. Four heat exchange experiments and standardized window performance metrics (U-factor, SHGC, and visible transmission) where conducted on seven H2Owindows. The top two H2Owindows were then tested using Al2O3 nanofluids. The highest performing Nanowindow improved total convective heat transfer rates using Al2O3 by 90% over water baseline, and 61% improvement in preheat water experiments. Nanowindows coupled with thermoelectric generators generated a rated voltage of 0.31VDC/0.075ADC per 12in2 Nanowindow, an improvement of 38% over baseline. Standardized window performance metrics confirmed Nanowindow U-factors ranging from 0.23 to 0.54, SHGC from 0.43 to 0.67, and visible transmittance coefficient (VT) ranging from 0.27 to 0.38. The concept of nature as model system thinking provided a theoretical framework for the research and proof of concept experiment. Ultimately, the experiment shifted window gaps from resisting energy to harnessing solar energy. The Nanowindow thus presents a unique opportunity to turn vast glass facades into transparent generators to offset energy demand, and reduce greenhouse gases.

This thesis examines the widespread moisture problems which emerged over the past twenty years in buildings throughout coastal British Columbia, commonly known as ‘leaky condos’. A literature review of building physics and a historical review of wood-frame construction in North America provide background for this review. The purpose of this work is to report and interpret the performance of rainscreen walls in the coastal climate of Vancouver BC, based on extensive field data from five local buildings constructed or rehabilitated with rainscreen wall assemblies. Hygrothermal data was collected within exterior walls, and corresponding environmental data was recorded for each building. Driving rain loads at the five buildings across the city are calculated and compared to Vancouver airport data. Site factors are shown to have a significant impact on driving rain load, wind speed and direction. The WUFI 4.1 hygrothermal model was compared with the field data collected and found to be accurate at predicting past performance. Applying this validated model to each wall assembly, further simulations were performed to determine the impact of boundary conditions and assembly details on wall performance. Field measurements and modeling show that ventilated and drained claddings (i.e. rainscreen) reduce the sensitivity of wood frame buildings to moisture damage. Ventilation of the cladding is shown to be particularly important and natural buoyancy forces (from temperature and humidity differences between cavity and exterior) are usually sufficient to provide good drying. Exterior insulation is shown to further improve rainscreen wall performance by increasing the drying potential of the sheathing to both the exterior and interior. Additional work performed included material testing of fiberglass-faced gypsum sheathing and air-leakage testing of individual suites in the monitored buildings. Elevated interior humidity, resulting from inadequate ventilation, is shown to be exacerbated by inter-zonal air-flow in multi-unit residential buildings.

The primary objective of this study was to investigate mould growth resistance of different types of wood products which include the sheathing and framing within full scale wall assemblies. Secondary objectives were to investigate the difference in mould growth resistance between borate-treated and untreated wood products as well as provide information about mould growth under different temperature and humidity conditions for treated and untreated wood products. <br /><br /> The objective of the study is to better understand mould growth, and to examine the effects of varying high moisture conditions on wooden products and the mould growth which may result. More importantly this will be examined on full scale wall assemblies; to date mould growth studies have only been performed within a laboratory on small samples of materials. Moreover, this study recreates the conditions which evidently cause mould growth on full scale wall assemblies. Tests were performed within a climate chamber on three full scale wall assemblies. The original scope of this study included an examination of the sheathing and framing components within a full scale wall assembly, however this study will focus mainly on the sheathing. <br /><br /> Results of this study indicate that the relative humidity conditions needed for mould growth on wood are higher than originally believed (i. e. , significantly greater than 80%RH). During the first eight weeks of test number one the relative humidity at the surface of the sheathing was held constant at 95% and little mould growth was observed on the untreated sheathing (mould growth index of 3 or less); little or no mould growth on the treated sheathing (mould growth index of 1 or less). The second and third tests demonstrated that the presence of liquid water greatly accelerated the time to germinations, the amount of mould growth (up to a mould growth index of 6), and the rate of mould growth. All three tests clearly showed that borate-treatment reduced the amount of mould growth; however, the concentration of borate-treatment, and the types of materials treated, does affect the resistance of mould growth. Furthermore, there was some evidence to suggest Borate treatments of the plywood increased the time to germination significantly, from a few weeks to 16 weeks in this study, but once mould growth was initiated, the rate of mould growth was similar to that of the untreated plywood. Two mathematical models to determine mould growth were examined: Viitanen and WUFIBIO (Sedlbauer). Viitanen?s model predicted time to germination and rate of growth rate well for untreated plywood, and WUFIBIO predicted time to germination but not the growth rate. It was also found both models err on the side of caution in predicting mould growth. <br /><br /> Recommendations include improvements to the test method and producers, and for future work.

This thesis examines the widespread moisture problems which emerged over the past twenty years in buildings throughout coastal British Columbia, commonly known as ‘leaky condos’. A literature review of building physics and a historical review of wood-frame construction in North America provide background for this review. The purpose of this work is to report and interpret the performance of rainscreen walls in the coastal climate of Vancouver BC, based on extensive field data from five local buildings constructed or rehabilitated with rainscreen wall assemblies. Hygrothermal data was collected within exterior walls, and corresponding environmental data was recorded for each building. Driving rain loads at the five buildings across the city are calculated and compared to Vancouver airport data. Site factors are shown to have a significant impact on driving rain load, wind speed and direction. The WUFI 4.1 hygrothermal model was compared with the field data collected and found to be accurate at predicting past performance. Applying this validated model to each wall assembly, further simulations were performed to determine the impact of boundary conditions and assembly details on wall performance. Field measurements and modeling show that ventilated and drained claddings (i.e. rainscreen) reduce the sensitivity of wood frame buildings to moisture damage. Ventilation of the cladding is shown to be particularly important and natural buoyancy forces (from temperature and humidity differences between cavity and exterior) are usually sufficient to provide good drying. Exterior insulation is shown to further improve rainscreen wall performance by increasing the drying potential of the sheathing to both the exterior and interior. Additional work performed included material testing of fiberglass-faced gypsum sheathing and air-leakage testing of individual suites in the monitored buildings. Elevated interior humidity, resulting from inadequate ventilation, is shown to be exacerbated by inter-zonal air-flow in multi-unit residential buildings.

The concern of increasing energy consumption with depleting energy resources is ever growing. Though the solution to this problem lies in part in renewable energies, it is becoming increasingly clear that sustainable building design also plays a critical role. Controlling solar gain, for example, can greatly reduce the cooling energy consumption and lowering the peak cooling load. Having the ability to model these effects can have a substantial impact on the sizing of equipment and further reduce operational costs of a building. As a result, renewed interest has been invested by researchers and industry to promote the development and use of building simulation tools to aid in the design process. Efforts at the University of Waterloo’s Advanced Glazing Systems Laboratory have resulted in a set of shading device models, with emphasis on generality and computational efficiency, tailored for use in building simulation. These models have been validated with measurements at the component level and with measurements performed at the National Solar Test Facility (NSTF) on a full scale window system, giving confidence to model validity. Continued research has resulted in the integration of these shading device models into ESP-r via the Complex Fenestration Construction (CFC) module, capable of modelling multi-layer glazing and shading layer systems and greatly improving the value of ESP-r as a design tool. The objective of the current research was to implement shading device models for roller blinds, pleated drapes and insect screens to the CFC module. These would be in addition to the venetian blind model which had previously been established. A Monte-Carlo ray tracing analysis of pleated drape geometry and incident angle dependent fabric characteristics gave further confidence to the view factor or net reduction method used by the implemented models. On model implementation, a preliminary comparison was performed between a high-slat angle venetian blind, a roller drape and drapery fabric, all given the same material properties, with similar results. Further comparison was then performed using EnergyPlus shading device models to establish further confidence in the functionality of the models. Though there was some discrepancy between the results, primarily due to convective models, good agreement was found, and the effect of the shading device models on building performance was demonstrated. The successful implementation of roller blind, pleated drape and insect screen shading models to the CFC module in ESP-r has been demonstrated in the current research. It should also be noted that the convective models for indoor shading attachments is a worthwhile topic for further research, at which point it would then be beneficial to conduct further empirical validation on the ESP-r simulation.

Wood is a highly versatile renewable material (with carbon sequestering properties), that is light in weight, has good strength properties in both tension and compression while providing good rigidity and toughness, and good insulating properties (relative to typical structural materials). Engineered wood products combine the benefits of wood with engineering knowledge to create optimized structural elements. Cross-laminated timber (CLT), as one such engineered wood product, is an emerging engineering material which provides great opportunities for the building industry. While building with wood has many benefits, there are also some concerns, particularly decay. Should wood be exposed to elevated amounts of moisture, rots and moulds may damage the product or even risk the health of the occupants. As CLT panels are a relatively new engineered wood product, the moisture characteristics have yet to be properly assessed. Consequently, the amount of decay risk for CLT in building applications is unknown, and recommended protective actions during design construction and operation have yet to be determined. The goal of this research was to determine the moisture durability of CLT panels in wall assemblies and address concerns related to built-in construction moisture. The approach used to address the problem was to first determine select moisture properties of CLT panels through experimental approaches, and then use the results to calibrate a hygrothermal model to quantify the risks of wall assemblies. The wall assemblies were simulated in six different cities across Canada, representing a range of climates: Vancouver, B.C., Edmonton, A.B., Winnipeg, M.B., Ottawa, O.N., Québec City, Q.C., and St. John, New-Brunswick. The risks associated with moisture exposure during construction are also considered in the simulations. The experimental phase of the research was limited to moisture uptake tests. These tests were utilized to determine the liquid water absorption coefficient for four different types of full scale panels (2’x2’) and 12 clear wood samples. The panels were either made of 5-ply of Western-SPF, Eastern-SPF, Hemlock-Fir, or 3-ply of a generic softwood provided by a European CLT manufacturer; the clear samples were all cut from the same nominal 2x6 SPF-grade lumber. The panels were installed in a drying rack and gravimetrically tracked to assess the drying rates of the panels. Finite resources precluded more thorough material testing, but a parametric study was conducted to determine the relative impact of the missing material data on the final simulation results. In the hygrothermal simulations, four main wall assembly types were considered- those with either exterior or interior insulation, and those using either vapour permeable or impermeable air-water barriers. Various types of insulation and vapour control were also modelled. The simulations were run for a variety of interior relative humidities. The metric for comparison between the simulations was the water content of a 4mm thin layer on the extreme lamina of a CLT panel system. The results of the simulation suggest that vapour impermeable membranes, when install on dry CLT panels (less than 14% M.C.) do not pose moisture risks in any of the climates considered. However, when high levels of construction moisture is considered, only vapour permeable membranes controlled moisture risks by allowing the CLT panel to dry both to the interior and to the exterior.

Residential and light-commercial buildings comprise a significant portion of buildings in the United States. They account for a large fraction of the total amount of energy used in the U.S., and they also represent environments where people spend the majority of their time. Thus, the design, construction, and operation of these buildings and their systems greatly affect energy consumption and exposures to airborne pollutants of both indoor and outdoor origin. However, there remains a need to improve knowledge of some key source and removal mechanisms of indoor and outdoor pollutants in residential and light-commercial buildings, as well as their connections to energy use and peak electricity demand. Several standardized field test methods exist for characterizing energy use and indoor air quality in actual buildings, although few explicitly address residential and light-commercial buildings and they are generally limited in scope. Therefore, the work in this dissertation focuses on improving methods to characterize three particular building components for their impacts on exposures to indoor pollutants and their implications for energy consumption: (1) central forced-air heating and cooling (HAC) systems, (2) HAC filters, and (3) building envelopes. Specifically, the research in this dissertation is grouped to fulfill two primary objectives of developing and applying novel methods to: (1) characterize and evaluate central air-conditioning systems and their filters as pollutant removal devices in residential and light-commercial buildings, and to explore their implications for energy consumption, and (2) characterize and evaluate the ability of two particular outdoor pollutants of concern (ozone and particulate matter) to infiltrate indoors through leaks in building envelopes. The research in this dissertation is divided into four primary investigations that fulfill these two objectives. The first investigation (Investigation 1a) addresses Objective 1 by first providing a detailed characterization of a variety of operational characteristics measured in a sample of 17 existing central HAC systems in occupied residential and light-commercial buildings in Austin, Texas, and exploring their implications for exposure to indoor pollutants, energy use, and peak electricity demand. Among the findings in this study, central air-conditioning systems in occupied residential and light-commercial buildings did not operate most of the time, even in the hot and humid climate of Austin, Texas (i.e., ~25% of the time on average in the summer). However, average recirculation rates still make central air-conditioning systems competitive as particle removal mechanisms, given sufficient filtration efficiency. Additionally, this investigation used a larger, much broader, dataset of energy audits performed on nearly 5000 single-family homes in Austin to explore common inefficiencies in the building stock. Residential and light-commercial air-conditioning systems are often inefficient; in fact, residential central air-conditioning systems in particular likely account for nearly 20% of peak electric demand in the City of Austin. As much as 8% of peak demand could be saved by upgrading all single-family homes in Austin to higher-efficiency equipment. The second investigation (Investigation 1b) also addresses Objective 1 by developing and applying a novel test method for measuring the in-situ particle removal efficiency of HAC systems and filters in residential and light-commercial buildings. Results from the novel test method as performed with three test filters and 0.3–10 μm particles in an unoccupied test house agreed reasonably well with results from other field and laboratory test methods. Low-efficiency filters did not increase particle removal much more than simply running the HAC system without a filter, and higher-efficiency filters provided greater than ~50% removal efficiency for most particles greater than 1–2 μm in diameter. The benefit of this test method is that it can be used to measure how filters perform in actual environments, how filter removal efficiency changes with actual dust loading, and how much common HAC design and installation issues, such as low airflow rates, duct leakage, fouled coils, and filter bypass airflow, impact particle removal in real environments. The third investigation (Investigation 2a) addresses Objective 2 by developing and applying a novel test methodology for measuring the penetration of outdoor ozone, a reactive gas, through leaks in exterior building envelopes using a sample of 8 single-family residences in Austin, Texas. These measurements represent the first ever measurements of ozone penetration factors through building envelopes of which I am aware, and penetration factors were lower than the usual assumption of unity (i.e., P = 1) in seven of the eight test homes (ranging from 0.62±0.09 to 1.02±0.15), meaning that some building envelopes provide occupants with more protection from indoor exposures to ozone and ozone reaction byproducts than others. Additionally, ozone penetration factors were correlated with some building characteristics, including the amount of painted wood siding on the exterior envelope and the year of construction, suggesting that simple building details may be used to predict ozone infiltration into homes. Finally, the fourth investigation (Investigation 2b) also addresses Objective 2 by refining and applying a test methodology for measuring the penetration of ambient particulate matter through leaks in building envelopes, and using a sample of 19 single-family residences in Austin, Texas to explore correlations between experimentally-determined particle penetration factors and standardized fan pressurization air leakage tests. Penetration factors of particles 20–1000 nm in diameter ranged from 0.17±0.03 to 0.72±0.08 across 19 homes that relied solely on infiltration for ventilation air. Particle penetration factors were also significantly correlated with results from standardized fan pressurization (i.e., blower door) air leakage tests and the year of construction, suggesting that occupants of older and leakier homes are exposed to more particulate matter of outdoor origin than those in newer tighter homes. Additionally, blower door tests may actually offer some predictive ability of particle penetration factors in single-family homes, which could allow for vast improvements in making easier population exposure estimates. Overall, the work in this dissertation provides new methods and data for assessing the impacts of central air-conditioning systems, filters, and building envelopes on human exposure to indoor pollutants and energy use in residential and light-commercial buildings. Results from these four primary investigations will allow building scientists, modelers, system designers, policymakers, and health scientists to make better informed decisions and assumptions about source and removal mechanisms of indoor pollutants and their impacts on building energy consumption and peak electricity demand. / text

As in-suite heat recovery ventilator (HRV) use increases, cases of cross-contamination and odour transmission in MURBs are beginning to appear. To mitigate these issues and maximize HRV benefits, a better design and construction methodology specific to MURBs is required. Previously conducted condition surveys suggest the possibility of the fresh air supply becoming contaminated by the exhaust air stream from adjacent units. It is suggested that the intake and exhaust configuration has a significant influence on the potential for cross contamination. The results show cross contamination is an issue in high-rise condominiums. With a low exhaust vent angle and the right wind direction and speed, contaminants can travel from an exhaust source to a fresh air supply in a significant quantity. The potential impact here is to protect the health and safety of all home owners living in high-rise condominiums that utilize in-suite ventilation systems.

As in-suite heat recovery ventilator (HRV) use increases, cases of cross-contamination and odour transmission in MURBs are beginning to appear. To mitigate these issues and maximize HRV benefits, a better design and construction methodology specific to MURBs is required. Previously conducted condition surveys suggest the possibility of the fresh air supply becoming contaminated by the exhaust air stream from adjacent units. It is suggested that the intake and exhaust configuration has a significant influence on the potential for cross contamination. The results show cross contamination is an issue in high-rise condominiums. With a low exhaust vent angle and the right wind direction and speed, contaminants can travel from an exhaust source to a fresh air supply in a significant quantity. The potential impact here is to protect the health and safety of all home owners living in high-rise condominiums that utilize in-suite ventilation systems.