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Building energy retrofits can reduce emissions and increase cost savings. Some retrofits that can deliver higher emissions savings are not popular due to a lack of economic justifications. Financial incentives can be used to change buyer perception around such retrofits. This study proposes a framework to identify the best-performing retrofit strategies for a given building cluster and the optimal incentive amounts to promote the chosen strategies, accounting for uncertainties, stakeholder priorities, and budget constraints. The proposed framework was demonstrated using a case study complemented with policy insights. Life cycle cost savings and capital cost significantly impact retrofit purchase decisions. Case study results showed that retrofitting houses heated with electricity can produce significant cost savings. However, adopting energy-conscious behaviours in houses heated with natural gas and injecting renewable natural gas into the gas supply can produce two times more emissions savings achieved by any retrofit strategy applied to an electrically heated house. This indicates the need for adopting performance-based incentives over the prescriptive approach to reward occupant efforts in addition to asset performance. Despite potential life cycle cost savings, incentives must be complemented with low-interest loans to promote retrofit strategies carrying higher capital costs. [ABSTRACT FROM AUTHOR]

Bridges are an integral part of a country's transportation infrastructure system. Earthquake-induced damages to bridges could result in fatalities and injuries, disturbances to the transportation infrastructure system, and incur significant repair costs. Furthermore, bridges must stay functional following an earthquake to maintain the continuity of transportation. Thus, innovative high-performance materials in the critical regions of structures and/or structural systems must be used located in regions of high seismic activity to mitigate the impacts of earthquakes. Despite having a higher seismic resilience, these structures, in general, tend to require a greater capital investment as a result of utilizing expensive material and special workmanship. However, when accounting for the postearthquake repair and maintenance costs, these seismically enhanced bridges can deliver significant cost advantages over conventional structures in the long run. Even so, the outcomes depend on the frequency and severity of the seismic damage, the lifespan of the bridge, the cost of materials, and the embodied emissions of the structures. To ensure better overall results, the cost–benefit analysis should be done with a life-cycle thinking perspective when comparing and making a decision related to multiple bridge systems. In this regard, a decision framework is developed to evaluate the overall life cycle performance of such a novel bridge, using fuzzy logic to integrate uncertainty. The proposed framework will assist engineers and the construction industry as a whole in making informed decisions regarding bridge infrastructure planning under dynamic conditions. [ABSTRACT FROM AUTHOR]

Building energy retrofits have been identified as key to realizing climate mitigation goals in Canada. However, retrofit solutions that only produce greenhouse gas emission savings can place economic burdens on residential building owners and hinder the community penetration of building energy retrofitting projects. Therefore, investigating trade-offs between environmental and economic impacts of retrofitting is essential to identify optimal retrofit strategies that can produce emissions savings while delivering economic benefits for the stakeholders. This paper proposes a community-level building energy retrofit evaluation framework for residential buildings. The proposed framework evaluates building energy retrofits using a multi-objective optimization approach that accounts for associated life cycle economic and environmental impacts. Life cycle CO 2 emissions were selected as the indicator for environmental performance. The net present value of the cash flows involved in a given retrofit project throughout the project life cycle was selected as the economic performance indicator. Building energy simulation results were combined with economic and environmental impact data to quantify these performance indicators. The performance results were used to identify Pareto-optimal retrofit solutions. The results indicate that retrofitting existing residential buildings can produce considerable emission reductions (up to 245.1 tonCO 2 eq/residence) and cost savings (up to 12,900 $/residence). Moreover, retrofit packages should prioritize upgrading building envelope insulation and space heating systems. This study introduces a decision support tool for community-level retrofit planners that can account for life cycle environmental and life cycle economic performance of retrofitting while fulfilling capital investment constraints. • Energy retrofits were evaluated using life cycle assessment and cost analysis. • The trade-offs between life cycle emissions and costs were explored. • Optimal retrofit packages for residential buildings were identified. • Natural gas heated buildings should be prioritized for retrofitting. • Strategies for promoting community-level retrofit programs were proposed. [ABSTRACT FROM AUTHOR]

• A retrofit selection strategy employing economic and environmental decision criteria was proposed. • Building energy retrofits were evaluated through a life cycle thinking approach. • Retrofits with operational emissions savings may not be beneficial when considering life cycle impacts. • Energy mix and the heating system of the house greatly impact the effectiveness. • Retrofit selection changes with stakeholder priorities on environment and economics. Improving the energy performance of buildings has been a much-discussed topic over the past few decades. With the current focus on climate change mitigation, emissions reduction has also come to the forefront of this discussion. Retrofitting is an option to improve the energy and emissions performance of buildings. However, in the residential building stock, retrofit planning for existing buildings faces many complexities due to variations in climatic conditions and macro-environment as well as the presence of multiple stakeholder groups. Thus, in identifying solutions, it is necessary to take a holistic perspective that covers these different dimensions. In this paper, commonly used building energy retrofits were evaluated through a life cycle thinking approach. The performance of various retrofit options applicable for single family detached housing were evaluated using the HOT2000 energy simulation software package under the varying climatic conditions and energy supply scenarios across Canada. The retrofits were evaluated in terms of the additional investment, energy use and cost reduction achieved over the life cycle, and life cycle emissions reduction. The findings indicate that the provincial energy mix and the heating system of the house (i.e. electric or natural gas) play a major role in determining the effectiveness of a retrofit, and this "effectiveness" changes at different stakeholder levels. However, not all retrofits that reduce emissions make economic sense and vice versa when life cycle thinking comes into play. The findings will be useful for building owners and occupants as well as for policy developers and other decision makers interested in demand side management. [ABSTRACT FROM AUTHOR]

Planning decentralised community-level hybrid energy systems has emerged as a solution to the various environmental and economic issues associated with conventional centralised energy supply systems. However, the optimal planning of community energy systems is a challenging issue due to the complexities, uncertainties, conflicting objectives, and high computational times in analysis. This study introduces a new multi-objective model based on weighted goal programming and grey pairwise comparison to assess renewable energy-based strategies in the case of net-zero energy communities. The problem was formulated to determine the optimal energy mix based on minimization of life cycle impacts and costs and maximization of renewable contributions and operational energy savings. To this end, binary integer and continues variables were applied on the code developed in a CPLEX environment. A pairwise comparison based on grey numbers was used to find the impacts of the goals in the objective function of the model under uncertainty. In addition to the grey-based weighting scenario, different weighting scenarios were employed to consider the importance of all goals on the system. These weighting scenarios were used to investigate the effects of changing decision priorities on the outcomes and on stakeholder interests at different levels. The developed goal-programming model was applied to the data of a case example and solved based on the weighting scenarios. Results indicated that the model is capable of finding the best possible strategies with the lowest total undesirable deviations from the desired levels of the goals compared to the literature of the decision-making techniques. The integration of maximum renewable energy (RE) supply in the energy mix with the locally available energy resources can deliver considerable benefits in terms of energy supply cost reduction as well as in mitigating life cycle environmental impacts. When environmental goals are prioritized, integrating low emissions RE as much as possible and excluding waste-to-energy technologies makes best sense, while under a pro-economic perspective, solar integration is comparatively discouraged. The findings of the study are expected to assist community developers and other decision makers involved in regional energy planning. The developed method will also be of use for those who are interested in the use of goal programming to solve complex planning issues involving numerous uncertain parameters. • Energy planning involves multiple decision dimensions and requires multi-objective optimization. • Goal programming can be used to reduce computational time in complex optimization problems. • Optimal energy mix in community energy systems change based on decision priorities. • RE integration can deliver life cycle economic and environmental benefits for communities. [ABSTRACT FROM AUTHOR]

The ever-increasing anthropogenic greenhouse gas (GHG) emissions worldwide make it quite challenging to meet country-specific Nationally Determined Contributions (NDC) targets. Therefore, it is evident that the existing emissions abatement measures need to be taken a step further. Internationally Transferred Mitigation Outcomes (ITMOs) are allowed in Article 6.2 of the Paris Agreement as a cooperative approach to achieving NDC goals. There is a potential to create ITMOs between Canada and China by replacing coal use in China with British Columbia (BC)'s liquefied natural gas (LNG) supply. Replacing coal with LNG in energy generation applications is a promising approach to mitigate emissions. With global and national pressures to reduce emissions, China has created a market for LNG imports to cater to its rising natural gas (NG) consumption due to the coal-to-gas source switching strategy. However, the terms under Article 6.2 requires generated ITMOs to ensure environmental integrity, support sustainable development goals, and have a robust accounting system. Therefore, the current study aims to quantify the life cycle environmental outcomes of generating ITMOs by exporting LNG from BC to Chinese end-users while integrating uncertainties and to provide policy recommendations in adherence with the requirements of Article 6.2. Different LNG export scenarios were generated in the study and environmental impacts of each scenario were assessed and compared using a life cycle assessment (LCA) framework developed by the authors. Sensitivity and uncertainty analyses were conducted to understand the impacts created by the data uncertainties in the final result. By replacing conventional coal with NG, approximately 40–45% and 26%–32% emissions reductions can be obtainable for Chinese textile and chemical industries, respectively. The highest emissions reduction of approximately 60% was observed when coal is replaced with NG for district heating. The life cycle emissions (LCE) quantification framework provided in the study provides stakeholders with a systematic approach to determine the total GHG emissions and emissions reduction potential of different LNG export scenarios. [ABSTRACT FROM AUTHOR]