Kasun Hewage

1. Transportation systems are considered extremely important for global economic development, but this sector contributes significantly to greenhouse gas (GHG) emissions, which in turn drive climat...

1. Decarbonizing the transportation sector is widely recognized as a critical component of global climate mitigation strategies, with light-duty vehicles (LDVs) among the largest and most persisten...

Energy retrofits are essential for reducing building energy consumption and associated greenhouse gas (GHG) emissions. Occupancy patterns and occupant behaviors can significantly influence building energy performance and, consequently, the effectiveness of retrofit interventions. As such, it is critical to account for occupant factors when evaluating retrofit strategies. This study proposes an occupant-centric energy retrofit evaluation and optimization framework for Canadian residential buildings, grounded in a life cycle thinking approach. The research first assessed the impact of occupancy patterns and occupant behaviors on retrofit performance using a physics-based energy modeling approach. Then, energy modeling outputs were subsequently integrated with life cycle assessment and costing to evaluate the emission and cost outcomes of retrofit packages. Finally, multi-objective Pareto optimization was applied to identify optimal retrofit packages tailored to distinct occupant personas, based on trade-offs between life cycle GHG emissions and costs. Results demonstrate that cost-optimal packages achieved over $3,500 in life cycle savings per household, while emission-optimal packages reduced life cycle GHG emissions by over 113 tonnes of CO₂eq per home. The proposed framework offers a comprehensive tool for analyzing occupant-driven variability in retrofit outcomes and supports decision-making for stakeholders aiming to implement cost-effective and low-carbon retrofit programs.

Provides readers with a conceptual overview of how this research was conducted and its workflow. Lack of access to clean and safe drinking water has been an ongoing crisis for many Small and Rural Indigenous (SRI) communities. A risk assessment framework was proposed and demonstrated using the data of two SRI communities in British Columbia, Canada. Initially, a literature review was conducted to identify risks primarily occurring at upstream stages of water infrastructure. These risks at the upstream stage were categorized using criteria and indicators. Four criteria, i.e., Systematic Inequity, Compliance Risk, Strategic Risk, and Governance Risk, were established and further mapped over twenty-nine (29) indicators – qualitatively evaluated as low, medium, and high categories. The risks occurring at downstream stages were assessed using the traditional human health risk assessment (HHRA) methodology. The framework facilitated the evaluation of the impact of upstream risks on downstream water quality. Compliance, systematic inequity, and governance risks were higher in Community 1. The arsenic levels in the drinking water of both communities are slightly above the conservative risk standard of 10−6 but were below the 10−4 benchmark. The proposed framework identifies risks at both upstream and downstream stages of water infrastructure, enabling decision-makers to target early-stage interventions and prevent upstream risks from propagating downstream.

The indoor environmental quality (IEQ) in buildings is vital for health, work efficiency, productivity, and the overall sustainability of buildings. IEQ is governed by four parameters: indoor air quality and thermal, acoustic, and visual comfort. The recent pandemic has compelled people to think beyond energy efficiency and refocus on the health, well-being, and productivity of building occupants. Despite numerous IEQ guidelines and standards, there remains a paucity of systematic research that critically examines the relationship between IEQ and building energy efficiency. This systematic review explores the existing equilibrium and identifies gaps between IEQ standards and building energy codes. Firstly, this review examined the status of the IEQ standards and identified that most of the North American IEQ guidelines cannot achieve energy efficiency targets. Secondly, existing building energy codes were reviewed to determine how well these codes fare with IEQ requirements. It was revealed that the expensive energy certification documents are more focused on IEQ than traditional energy codes. The identified factors indicate that most building energy codes can meet only indoor air quality thresholds (a subset of IEQ), while other parameters are inadequately addressed. This review revealed 19 relationships between IEQs and energy efficiency. Building energy code/IEQ guidelines developers could consider the identified 19 relationships to develop a combined set of guidelines/standards for future building stock. An integration model between IEQ and energy efficiency is proposed as a future research direction to contribute to the better design and construction of modern buildings. The findings will facilitate the construction of healthy and sustainable buildings, and they aim to generate new residential communities that achieve an optimal health–energy–carbon nexus.