Building Science

Permanent URI for this collectionhttps://hdl.handle.net/1807/90520

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Bayesian Causal Inference for Occupant-Centric Building System Operation
(ASHRAE, 2024) Ko, Jinyoung; Lee, Seungjae
The decarbonization of the building sector is important to achieve a carbon-neutral society since buildings account for 30 % of the total greenhouse gas emissions. Since it is widely acknowledged that the behavior and decision-making of building occupants significantly affect the level of carbon emissions from buildings, occupant-centric building operational strategies have been proposed to minimize energy consumption but satisfy their needs. Recent studies have introduced two issues in previous solutions with data-driven occupant modeling: (i) the importance of ensuring causal relationships between independent and dependent variables for building system operations and (ii) the vulnerability in prediction over unseen and heterogeneous data. To improve building energy solutions’ reliability considering the issues, implying causal structures between variables in occupant models is important for occupant-centric building operation. Nevertheless, identifying causal relationships between occupants’ perception and behavior and other factors is challenging in buildings because of the difficulty in disentangling the direct causal impact of one factor from other influencing factors. There have been two major reasons that make the quantification of the causal impacts challenging: difficulties in (i) conducting fully controlled experiments with real occupants and (ii) considering potential causal relationships with conventional statistical analysis over observational data. To deal with these challenges, modern data-driven causal inference methods have been proposed as promising tools to identify causal relationships and estimate causal effects from observed data. Implying causal inference methods in occupant modeling can improve the robustness of further occupant-centric building operations. In this regard, this study aims to (i) introduce a causal inference method with a Bayesian perspective to identify a causal structure from a synthetic dataset, (ii) develop a causal model based on the inferred causal structure, and (iii) evaluate the causal model’s performance compared with the performance of the association-based (non-causal) model. In the model evaluation, we considered two critical aspects: the estimation of true causal effects whereby independent variables impact a dependent variable and the assessment of prediction robustness to dataset shift. While the causal model estimated the true causal effects properly, the non-causal model fails to capture the causal impacts from the independent to dependent variables. Within the in-distribution dataset, both causal and non-causal models demonstrated comparable prediction performance. However, when evaluated on the Out-of-distribution dataset, the causal model showed an RMSE of 0.16 while the non-causal model indicated an RMSE of 2.86. The results show that the prediction model based on correct causal structure can outperform the non-causal model in two realms, (i) correct estimation of causal effects and (i) more robust prediction over dataset shift. Therefore, the causal models should be used for occupant-centric building operations such as optimal controllers or occupant-centric thermostat interfaces to ensure the causal effect of adjusting independent variables on dependent variables such as occupant comfort and behavior.
Indoor Dust as a Matrix for Surveillance of COVID-19
(Wiley, 2021-04-13) Renninger, Nicole; Nastasi, Nicholas; Bope, Ashleigh; Cochran, Samuel J; Haines, Sarah R; Balasubrahmaniam, Neeraja; Stuart, Katelyn; Bivins, Aaron; Bibby, Kyle; Hull, Natalie M; Dannemiller, Karen C
Ongoing disease surveillance is a critical tool to mitigate viral outbreaks, especially during a pandemic. Environmental monitoring has significant promise even following widespread vaccination among high-risk populations. The goal of this work is to demonstrate molecular severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) monitoring in bulk floor dust and related samples as a proof of concept of a noninvasive environmental surveillance methodology for coronavirus disease 2019 (COVID-19) and potentially other viral diseases. Surface swab, passive sampler, and bulk floor dust samples were collected from the rooms of individuals positive for COVID-19, and SARS-CoV-2 was measured with quantitative reverse transcription-PCR (RT-qPCR) and two digital PCR (dPCR) methods. Bulk dust samples had a geometric mean concentration of 163 copies/mg of dust and ranged from nondetects to 23,049 copies/mg of dust detected using droplet digital PCR (ddPCR). An average of 89% of bulk dust samples were positive for the virus by the detection methods compared to 55% of surface swabs and fewer on the passive sampler (19% carpet, 29% polystyrene). In bulk dust, SARS-CoV-2 was detected in 76%, 93%, and 97% of samples measured by qPCR, chip-based dPCR, and droplet dPCR, respectively. Detectable viral RNA in the bulk vacuum bags did not measurably decay over 4 weeks, despite the application of a disinfectant before room cleaning. Future monitoring efforts should further evaluate RNA persistence and heterogeneity in dust. This study did not measure virus infectivity in dust or potential transmission associated with dust. Overall, this work demonstrates that bulk floor dust is a potentially useful matrix for long-term monitoring of viral disease in high-risk populations and buildings.IMPORTANCE Environmental surveillance to assess pathogen presence within a community is proving to be a critical tool to protect public health, and it is especially relevant during the ongoing COVID-19 pandemic. Importantly, environmental surveillance tools also allow for the detection of asymptomatic disease carriers and for routine monitoring of a large number of people as has been shown for SARS-CoV-2 wastewater monitoring. However, additional monitoring techniques are needed to screen for outbreaks in high-risk settings such as congregate care facilities. Here, we demonstrate that SARS-CoV-2 can be detected in bulk floor dust collected from rooms housing infected individuals. This analysis suggests that dust may be a useful and efficient matrix for routine surveillance of viral disease.
Morphology and quantification of fungal growth in residential dust and carpets
(2020-05) Nastasi, Nicholas; Haines, Sarah R; Xu, Lingyi; da Silva, Hadler; Divjan, Adnan; Barnes, Mark A; Rappleye, Chad A; Perzanowski, Matthew S; Green, Brett J; Dannemiller, Karen C
Mold growth indoors is associated with negative human health effects, and this growth is limited by moisture availability. Dust deposited in carpet is an important source of human exposure due to potential elevated resuspension compared to hard floors. However, we need an improved understanding of fungal growth in dust and carpet to better estimate human exposure. The goal of this study was to compare fungal growth quantity and morphology in residential carpet under different environmental conditions, including equilibrium relative humidity (ERH) (50%, 85%, 90%, 95%, 100%), carpet fiber material (nylon, olefin, wool) and presence/absence of dust. We analyzed incubated carpet and dust samples from three Ohio homes for total fungal DNA, fungal allergen Alt a 1, and fungal morphology. Dust presence and elevated ERH (≥85%) were the most important variables that increased fungal growth. Elevated ERH increased mean fungal DNA concentration (P < 0.0001), for instance by approximately 1000 times at 100% compared to 50% ERH after two weeks. Microscopy also revealed more fungal growth at higher ERH. Fungal concentrations were up to 100 times higher in samples containing house dust compared to no dust. For fiber type, olefin had the least total fungal growth, and nylon had the most total fungi and A. alternata growth in unaltered dust. Increased ERH conditions were associated with increased Alt a 1 allergen concentration. The results of this study demonstrate that ERH, presence/absence of house dust, and carpet fiber type influence fungal growth and allergen production in residential carpet, which has implications for human exposure.
Ten questions concerning the implications of carpet on indoor chemistry and microbiology
(Elsevier, 2020) Haines, Sarah R; Adams, Rachel I; Boor, Brandon E; Bruton, Thomas A; Downey, John; Ferro, Andrea R; Gall, Elliott; Green, Brett J; Hegarty, Bridget; Horner, Elliott; Jacobs, David E; Lemieux, Paul; Misztal, Pawel K; Morrison, Glenn; Perzanowski, Matthew; Reponen, Tiina; Rush, Rachael E; Virgo, Troy; Alkhayri, Celine; Bope, Ashleigh; Cochran, Samuel; Cox, Jennie; Donohue, Allie; May, Andrew A; Nastasi, Nicholas; Nishioka, Marcia; Renninger, Nicole; Tian, Yilin; Uebel-Niemeier, Christina; Wilkinson, David; Wu, Tianren; Zambrana, Jordan; Dannemiller, Karen C
Carpet and rugs currently represent about half of the United States flooring market and offer many benefits as a flooring type. How carpets influence our exposure to both microorganisms and chemicals in indoor environments has important health implications but is not well understood. The goal of this manuscript is to consolidate what is known about how carpet impacts indoor chemistry and microbiology, as well as to identify the important research gaps that remain. After describing the current use of carpet indoors, questions focus on five specific areas: 1) indoor chemistry, 2) indoor microbiology, 3) resuspension and exposure, 4) current practices and future needs, and 5) sustainability. Overall, it is clear that carpet can influence our exposures to particles and volatile compounds in the indoor environment by acting as a direct source, as a reservoir of environmental contaminants, and as a surface supporting chemical and biological transformations. However, the health implications of these processes are not well known, nor how cleaning practices could be optimized to minimize potential negative impacts. Current standards and recommendations focus largely on carpets as a primary source of chemicals and on limiting moisture that would support microbial growth. Future research should consider enhancing knowledge related to the impact of carpet in the indoor environment and how we might improve the design and maintenance of this common material to reduce our exposure to harmful contaminants while retaining the benefits to consumers.
Modeling microbial growth in carpet dust exposed to diurnal variations in relative humidity using the "Time-of-Wetness" framework
(Wiley, 2020-09) Haines, Sarah R; Siegel, Jeffrey A; Dannemiller, Karen C
Resuspension of microbes in floor dust and subsequent inhalation by human occupants is an important source of human microbial exposure. Microbes in carpet dust grow at elevated levels of relative humidity, but rates of this growth are not well established, especially under changing conditions. The goal of this study was to model fungal growth in carpet dust based on indoor diurnal variations in relative humidity utilizing the time-of-wetness framework. A chamber study was conducted on carpet and dust collected from 19 homes in Ohio, USA and exposed to varying moisture conditions of 50%, 85%, and 100% relative humidity. Fungal growth followed the two activation regime model, while bacterial growth could not be evaluated using the framework. Collection site was a stronger driver of species composition (P = 0.001, R2 = 0.461) than moisture conditions (P = 0.001, R2 = 0.021). Maximum moisture condition was associated with species composition within some individual sites (P = 0.001-0.02, R2 = 0.1-0.33). Aspergillus, Penicillium, and Wallemia were common fungal genera found among samples at elevated moisture conditions. These findings can inform future studies of associations between dampness/mold in homes and health outcomes and allow for prediction of microbial growth in the indoor environment.
Microbial growth and volatile organic compound (VOC) emissions from carpet and drywall under elevated relative humidity conditions
(2021-10-19) Haines, Sarah R.; Hall, Emma C.; Marciniak, Katarzyna; Misztal, Pawel K.; Goldstein, Allen H.; Adams, Rachel I.; Dannemiller, Karen C.
Abstract Background Microbes can grow in indoor environments if moisture is available, and we need an improved understanding of how this growth contributes to emissions of microbial volatile organic compounds (mVOCs). The goal of this study was to measure how moisture levels, building material type, collection site, and microbial species composition impact microbial growth and emissions of mVOCs. We subjected two common building materials, drywall, and carpet, to treatments with varying moisture availability and measured microbial communities and mVOC emissions. Results Fungal growth occurred in samples at >75% equilibrium relative humidity (ERH) for carpet with dust and >85% ERH for inoculated painted drywall. In addition to incubated relative humidity level, dust sample collection site (adonis p=0.001) and material type (drywall, carpet, adonis p=0.001) drove fungal and bacterial species composition. Increased relative humidity was associated with decreased microbial species diversity in samples of carpet with dust (adonis p= 0.005). Abundant volatile organic compounds (VOCs) that accounted for >1% emissions were likely released from building materials and the dust itself. However, certain mVOCs were associated with microbial growth from carpet with dust such as C10H16H+ (monoterpenes) and C2H6SH+ (dimethyl sulfide and ethanethiol). CO2 production from samples of carpet with dust at 95% ERH averaged 5.92 mg hr-1 kg-1, while the average for carpet without dust at 95% ERH was 2.55 mg hr-1 kg-1. Conclusion Microbial growth and mVOC emissions occur at lower relative humidity in carpet and floor dust compared to drywall, which has important implications for human exposure. Even under elevated relative humidity conditions, the VOC emissions profile is dominated by non-microbial VOCs, although potential mVOCs may dominate odor production. Video Abstract
Degradation of phthalate esters in floor dust at elevated relative humidity
(Royal Society of Chemistry, 2019-08-14) Bope, Ashleigh; Haines, Sarah R; Hegarty, Bridget; Weschler, Charles J; Peccia, Jordan; Dannemiller, Karen C
Emerging investigator series: Phthalate esters are present at elevated concentrations in floor dust, and resuspension of dust represents a major source for human exposure to chemicals. Biodegradation of phthalates occurs in aquatic systems and soils but has not been demonstrated in house dust. The goal of this study was to quantify indoor phthalate ester degradation through both biotic and abiotic mechanisms. Worn carpet squares were embedded with dust and incubated for one to six weeks at equilibrium relative humidity (ERH) levels of 50, 80, 85, 90, 95, and 100%, and nine phthalates were measured. Removal was observed for DEHP, BBzP, DINP, DiDP, and DMP (p < 0.05) when incubated under elevated relative humidity conditions. Abiotic and biotic losses were examined separately using dust spiked with deuterated di(2-ethylhexyl)phthalate (d-DEHP) that was embedded in carpet and incubated at 100% ERH. Abiotic processes resulted in a 10.1% (±1.1%, standard error) to 69.6% (±4.8%) decrease in total d-DEHP after one week (p = 0.03) and a 27.2% (±1.4%) to 52.0% (±2.1%) decrease after three weeks (p = 0.008). Biodegradation resulted in a decrease in total d-DEHP after one week, ranging from 5.9% (±8.9%) to 8.5% (±1.7%) (p = 0.07) and a 1.7% (±3.9%) to 10.3% (±4.5%) decrease after three weeks (p = 0.044). Metatranscriptomic-based analysis indicates that fungi found in carpet dust express genes capable of degrading phthalate esters via various biochemical processes (including β-oxidation and hydrolysis). Overall, these results support the hypothesis that phthalate losses in floor dust are due to a combination of abiotic and microbial degradation at ≥80% ERH.
Inter-zonal airflow in multi-unit residential buildings: A review of the magnitude and interaction of driving forces, measurement techniques and magnitudes, and its impact on building performance
(Wiley, 2020-07-08) Lozinsky, Cara H; Touchie, Marianne F
Inter-zonal airflows within multi-unit residential buildings (MURBs) have profound impacts on an array of building performance metrics, including energy, indoor air quality (IAQ), fire and acoustical separations, and distribution of ventilation air. Although there are wide-ranging implications, most building codes/standards have yet to incorporate airtightness requirements for interior partitions in large, multi-zone structures, and instead focus primarily on exterior envelope airtightness. Despite the multi-disciplinary nature of the topic, previous reviews have been limited to one domain (eg, energy performance, IAQ, specific test methods). This paper presents a comprehensive summary of the literature on inter-zonal airflow in MURBs including the magnitude and interaction of driving forces; its relevance to/effect on building performance; current code requirements; testing methods; and previous measurements. While considerable efforts have been made in recent years to quantify and control inter-zonal airflows, most measurement techniques are still labor-intensive and disruptive, and there is no framework for how to implement performance-based requirements into building codes and standards. Further research efforts should be focused on refining testing methods and preparing the construction industry for code changes.
A simulation framework for predicting occupant thermal sensation in perimeter zones of buildings considering direct solar radiation and ankle draft
(Elsevier, 2020-07-11) Zhang, Shengbo; Fine, Jamie P.; Touchie, Marianne F.; O'Brien, William
Buildings with highly glazed envelopes have gained popularity in recent decades. Though it is well understood that these modern buildings can be less energy efficient, only a few attempts have been made to examine the impact of certain building design decisions, such as window characteristics, on indoor thermal sensation and thermal comfort. While conventional assessment of thermal sensation and comfort primarily considers zone-level environmental conditions (e.g. air temperature and relative humidity), localized effects including direct solar radiation exposure and ankle draft may also exist and can impact indoor thermal sensation especially in highly glazed perimeter zones. In this work, a simulation framework is introduced to incorporate the solar radiation effect and ankle draft effect, which are shown to increase warm and cold thermal sensation levels, respectively. The novel proposed ankle draft model adapts local draft conditions to determine the impact on overall thermal sensation for the first time. This simulation framework is demonstrated using a single-zone model using the climate of Toronto, Canada to illustrate the effect of three primary window design parameters on thermal sensation using a visualization approach: window size, U-factor, and solar heat gain coefficient. All observations are aligned with anecdotal evidence: warm thermal sensation level is positively correlated with window size and solar heat gain coefficient, whereas cold thermal sensation level is positively correlated with window size and window U-factor. This simulation framework can be used to analyze indoor thermal sensation and comfort for perimeter zones in existing buildings or fenestration alternatives during building design phases.
Development of the selective pressure neutralization method – An air tightness test method for exterior pressure boundary characterization in high-rise residential buildings
(Elsevier, 2021-03-13) Fine, Jamie P.; Lozinsky, Cara H.; Touchie, Marianne F.
This paper presents a novel method for characterizing the exterior envelope air tightness of high-rise multi-unit residential building suites, the “Selective Pressure Neutralization” (Selective PN) method. Through the neutralization of air flow across the corridor-suite pressure boundary, this method can improve accuracy compared to the typically implemented “Whole Suite” method, while halving the time and equipment requirements of on-site testing compared to the Pressure Neutralization method. A CONTAM model was developed using field data from eight case study suites and then used to simulate the effectiveness of the proposed method in fourteen suite configurations. Sensitivity study simulations were also carried out where individual suite pressure boundary air tightness characteristics were varied. The case study results showed average absolute exterior boundary characterization errors of 16% and 51% for the Selective PN and Whole Suite methods, respectively. The sensitivity study results showed that the Selective PN method meets or exceeds the accuracy of the Whole Suite method by up to 78% in buildings with leakier exterior boundaries, like those in buildings with punched windows (as opposed to window wall configurations). Thus, the Selective PN method shows promise as an alternative air tightness testing method.
Is anyone home? A critical review of occupant-centric smart HVAC controls implementations in residential buildings
(Elsevier, 2021-01) Stopps, Helen; Huchuk, Brent; Touchie, Marianne F.; O'Brien, William
Smart home technologies have long been envisioned as a mainstay in future residential buildings; however, residential smart home technologies have fallen short of expectations. Generally referred to by the literature as occupant-centric controls (OCC), a subset of these technologies focus on sensing and/or managing systems based on occupant feedback, preferences, or perceptions. While past reviews have documented OCC applications in commercial and industrial building types, residential applications have been rarely distinguished as their own unique application of OCC. This article critically reviews the state-of-the art research in both simulation and field-experiments – neither of which fully align with existing commercial smart home OCC technologies. Study demographics, location, building systems, implementation objectives, and experimental methods are compared and critiqued to understand where research, through simulation and field-experiments, needs to be focused. Key identified shortcomings include: low diversity of studied building systems, overly simplified simulation scenarios, short durations of field testing, inappropriate choices of occupant types, and non-standardized implementation performance metrics and test cases. Furthermore, innovation is hampered by limited standardization in technology communication protocols, the inability to integrate systems from different manufacturers, missing technology transfer protocols to translate researched implementations into commercial applications, and a lack of vision and planning for future policies and technologies that enable effective and comprehensive smart home implementations.
Case study: A survey of perceived noise in Canadian multi-unit residential buildings to study long-term implications for widespread teleworking
(SAGE Publications, 2021-02-09) Andargie, Maedot S.; Touchie, Marianne; O’Brien, William
Trends of urbanization, densification, and telework all point to increasing exposure to ambient noise for workers. With the lockdown policies implemented in response to COVID-19, a research opportunity to study perceived noise exposure for teleworking arose. This paper presents the results of a survey on noise issues in multi-unit residential buildings (MURBs) and the consequent effects on occupants' well-being and productivity during the lockdown. Responses were collected from 471 MURB occupants across Canada. The results show that, despite the decrease in environmental noise, many are annoyed by outdoor noise, particularly from traffic and construction activities, and indicated that it affects their ability to work. Effects on ability to work from home were more frequently reported for indoor noise sources particularly airborne and impact noises coming from neighboring suites. Our findings, however, show that noise coming from occupants in the same suite (i.e. roommates and family) present the biggest issue. The findings indicate that existing noise conditions in MURBs might not be suitable for a permanent large-scale implementation of teleworking.
The Role of Occupants in Buildings’ Energy Performance Gap: Myth or Reality?
(2021-03-12) Mahdavi, Ardeshir; Berger, Christiane; Amin, Hadeer; Ampatzi, Eleni; Andersen, Rune Korsholm; Azar, Elie; Barthelmes, Verena M.; Favero, Matteo; Hahn, Jakob; Khovalyg, Dolaana; Knudsen, Henrik N.; Luna-Navarro, Alessandra; Roetzel, Astrid; Sangogboye, Fisayo C.; Schweiker, Marcel; Taheri, Mahnameh; Teli, Despoina; Touchie, Marianne; Verbruggen, Silke
Buildings’ expected (projected, simulated) energy use frequently does not match actual observations. This is commonly referred to as the energy performance gap. As such, many factors can contribute to the disagreement between expectations and observations. These include, for instance, uncertainty about buildings’ geometry, construction, systems, and weather conditions. However, the role of occupants in the energy performance gap has recently attracted much attention. It has even been suggested that occupants are the main cause of the energy performance gap. This, in turn, has led to suggestions that better models of occupant behavior can reduce the energy performance gap. The present effort aims at the review and evaluation of the evidence for such claims. To this end, a systematic literature search was conducted and relevant publications were identified and reviewed in detail. The review entailed the categorization of the studies according to the scope and strength of the evidence for occupants’ role in the energy performance gap. Moreover, deployed calculation and monitoring methods, normalization procedures, and reported causes and magnitudes of the energy performance gap were documented and evaluated. The results suggest that the role of occupants as significant or exclusive contributors to the energy performance gap is not sufficiently substantiated by evidence.
A Practical Simulation Framework for Thermal Sensation Analysis of Fenestration Designs
(2020-11) Zhang, Shengbo; Touchie, Marianne; O'Brien, William; Mechanical and Industrial Engineering
Buildings with highly glazed envelopes have gained popularity over the past decades. Though it is known that these buildings are less energy efficient, few attempts have been made to investigate their effect on thermal comfort apart from surveys. The gap between research and the industry arises because predicting thermal sensation is labourious and lacks suitable tools. In response, a simulation framework, which is the novelty of this work, is designed to reduce such effort. Direct solar radiation and ankle draught effects are considered since they have been shown to increase warm and cold sensation, respectively. Example applications using visualization and sensitivity analysis techniques suggest that window size increases both warm and cold sensation levels, which are also positively correlated with window overall solar heat gain coefficient and U-factor, respectively. The results from the example applications provide insights into how different window designs can affect thermal sensation within a similar context.
Impact of Residential HVAC Filters on Particle Concentration and Exposure
(2020-06) Zhang, Yizhi; Siegel, Jeffrey A.; Civil Engineering
Filters in heating, ventilating, and air conditioning (HVAC) systems can improve indoor air quality. In North America, residential air cleaning is usually done by recirculating indoor air through a filter. In this work, I explored two methods of assessing the impacts of HVAC filters in residences. The first method was through examining year-long PM measurements in 20 Toronto homes where different types of filters were installed. I found no evidence that higher efficiency filters reduced long-term exposure to PM. The second method was by studying the particle size distribution of filter dust. I explored the possibility of size separating filter dust to gain more information on smaller particles. One major challenge is the sticky nature of filter dust makes both the separation and mixing (with water for size analysis) processes difficult. Despite the caveats, these findings suggest that both methods are promising and can provide useful information for future studies.
In-situ Measurement of Ventilation and Impacts of Filtration on IEQ and Energy use of Residential Buildings
(2019-11) Alavy Ghahfarrokhy, Seyed Masih; Siegel, Jeffrey A; Civil Engineering
Indoor environmental quality (IEQ) impacts of filters in residential HVAC systems is a strong function of many HVAC system- and building-specific parameters. Furthermore, the energy consequences of filters can be important, and the magnitude and the sign of these energy impacts are system-specific as well. These system- and building-specific parameters can vary not only over different residential buildings, but also over the lifetime of a filter in a given building. A primary building-specific parameter that varies greatly over time is outdoor ventilation air change rate (ACR). ACR is not only an important particle removal mechanism, and a source of variations in filter IEQ performance, but it also is an important contributor to energy use in buildings. This work first critically reviews the existing literature on filtration and then presents an integrated evaluation of the overall IEQ and energy performance of higher efficiency residential filters. It also further develops the understanding of how ACR varies over time and how it influences filtration performance in residences. Yearlong measurement results from particle removal performance analysis of four different high efficiency filters placed in 21 residences in Toronto, Ontario showed that there was more variation in filter performance between the same filter in different homes than there was between different filters in the same home. In addition, increasing system runtime (ontime fraction) could also lead to higher particle removal impacts of filters. Study of energy consequences of the same filters in the same homes showed that fan energy consequences of high efficiency filters are negligible and because HVAC runtimes were generally low (median = 9.6%) in this sample of homes, the difference between energy consumption of different types of motor fans at typical runtimes was small (less than 10 kWh per month). Yearlong ACR measurements showed that ACR is a temporally dynamic parameter with timescales of minutes that varies considerably over long-term periods (e.g., geometric mean = 0.47/h, geometric standard deviation = 3.44 in one of the residences studied). Overall, this dissertation provides new methods and data for assessing the ventilation performance and impacts of filtration on IEQ and energy use of residential buildings.
Rethinking Performance Gaps: A Regenerative Sustainability Approach to Built Environment Performance Assessment
(MDPI, 2018-12-18) Coleman, Sylvia; Touchie, Marianne; Robinson, John; Peters, Terri
Globally, there are significant challenges to meeting built environment performance targets. The gaps found between the predicted performance of new or retrofit buildings and their actual performance impede an understanding of how to achieve these targets. This paper points to the importance of reliable and informative building performance assessments. We argue that if we are to make progress in achieving our climate goals, we need to reframe built environment performance with a shift to net positive goals, while recognising the equal importance of human and environmental outcomes. This paper presents a simple conceptual framework for built environment performance assessment and identifies three performance gaps: (i) Prediction Gap (e.g., modelled and measured energy, water consumption); (ii) Expectations Gap (e.g., occupant expectations in preand post-occupancy evaluations); and, (iii) Outcomes Gap (e.g., thermal comfort measurements and survey results). We question which of measured or experienced performance is the ‘true’ performance of the built environment. We further identify a “Prediction Paradox”, indicating that it may not be possible to achieve more accurate predictions of building performance at the early design stage. Instead, we propose that Performance Gaps be seen as creative resources, used to improve the resilience of design strategies through continuous monitoring.
Characterization of Pre-retrofit Air Flow in a 1970’s Multi-unit Residential Building in Toronto, Ontario
(2019-11) McCormack, Anna; Touchie, Marianne; Mechanical and Industrial Engineering
Many multi-unit residential buildings (MURBs) constructed in the 1970s do not meet current energy standards. Air leakage through the building envelope contributes significantly to energy losses in these buildings. Retrofits such as window replacements and over-cladding can improve the air tightness of the envelope but may have unintended consequences for the ventilation of the building. Pressure distributions throughout the building may change because of reduced leakage across the exterior walls leading to increased inter-zonal air flow. Air flow tests were performed in a 1970s MURB in its pre-retrofit condition. The tests showed significant leakage across building components including the windows and balcony doors. Occupant surveys indicated odour transfer between suites despite field tests that showed adequate air change rates and low inter-zonal air transfer between suites. Air flow network modelling showed that inter-zonal air flow will likely increase between select suites after envelope air tightening retrofits are completed.
A review of factors affecting occupant comfort in multi-unit residential buildings
(Elsevier, 2019-08) Andargie, Maedot S.; Touchie, Marianne; O'Brien, William
Traditionally, less focus has been given to comfort evaluations in residential buildings compared to commercial buildings. Despite having an increased level of control relative to offices, occupants can still experience health and comfort issues in their residences due to poor environmental conditions which can result in adaptations that may increase energy consumption in buildings. Consequently, there have been more studies which evaluate factors that affect occupant comfort and health in residential buildings in recent years. As high-rise multi-unit residential buildings (MURBs) become more ubiquitous in cities globally, researchers have also started to look at factors that affect occupants’ comfort in MURBs. In this paper, a critical review of studies which investigated occupant comfort in MURBs in relation to environmental and non-environmental variables that could have a potential impact on comfort is presented. Various approaches used in assessing occupant comfort are compared, the factors which are important determinants of occupant comfort in MURBs are presented, and the gaps in the literature are identified. Findings of this review show that, in addition to indoor environmental conditions, occupants’ characteristics, building-related characteristics and the outdoor environment can significantly affect occupant comfort in MURBs. The identified gaps include a limited assessment of the impact of non-thermal related environmental conditions on comfort and the impact of non-environmental related conditions, as well as a limited number of studies on health and productivity. Based on these findings, the paper includes recommendations on research design and methodologies for future occupant comfort studies in MURBs.
Improving energy model calibration of multi-unit residential buildings through component air infiltration testing
(Elsevier, 2018-04-15) Lozinsky, Cara H.; Touchie, Marianne F.
Building infiltration rates are one of the most uncertain parameters among multi-unit residential building (MURB) energy model inputs and have the potential to greatly impact building energy consumption. Infiltration rates exhibit high spatial and temporal variability and are highly building-specific making them difficult to estimate from published data. Reduction of parameter uncertainty using on-site measurements has traditionally been prohibitive, both from a cost and a logistical standpoint. Window component infiltration rate testing was conducted at two MURBs to develop component-weighted infiltration rates, which were input into whole-building energy models and compared with models that used a single building-level infiltration rate. The component-weighted infiltration rate allowed for the incorporation of building-specific measurements, which helped to reduce parameter uncertainty during model calibration. The component-weighted approach also helped to account for the variation in zone infiltration rates based on type and quantity of leakage paths. The discretization of the infiltration rate by building component can help during the modeling of energy retrofits that specifically target building infiltration, by setting bounds on the maximum possible improvement. Implementation of a component-weighted approach will help to improve model calibration and energy retrofit analysis in whole-building energy models, allowing owners and operators to make better-informed decisions regarding energy retrofits.

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