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Many countries are considering policy instruments such as a carbon tax and economic discounting to reduce greenhouse gas (GHG) emissions in key sectors like the water sector. This paper examines the impact of economic discounting and a carbon tax on the optimization of water main rehabilitation. A new pipe rehabilitation optimization algorithm that accounts for GHGs was developed and applied to the Fairfield water distribution system in Amherstview, Ontario, Canada. GHG intensity factors for the provinces of Ontario (low-carbon) and Alberta (high-carbon) were applied to the Fairfield network. In both cases, adopting a low discount rate and levying a carbon tax had a weak effect in reducing energy use, GHG emissions, pipe breaks, and leakage. Further, a low discount rate and a carbon tax encouraged the search process to invest in rehabilitation early in the planning period to reduce continuing leakage, pipe repair, energy, and GHG costs. [ABSTRACT FROM AUTHOR]

Building regulations and governmental policies create pressure on the construction industry to minimize the environmental impacts that are caused by buildings. Achieving energy efficiency, and thereby low-carbon construction, is only possible by cooperation among the participants in the construction supply chain. Clients in particular have an important role in promoting environmental sustainability. In this paper, the carbon-reduction process is analyzed from a construction client's perspective. A framework is developed to analyze the interrelated components of this process, including the drivers, initiatives, challenges, facilitators, solutions, and achievements. A qualitative case study methodology was employed to gain a better understanding of the project-based practices and corporate policies in achieving energy efficiency. The study presents the results of three award-winning construction projects from the U.K. in which innovations for improving environmental sustainability were based on the Code for Sustainable Homes. The study outlines the initiatives and strategies of clients for carbon reduction, obstacles faced by project teams, mechanisms that helped overcome the difficulties, and low-carbon solutions applied to design, construction, and operation in the selected cases. Effective leadership, corporate responsibility, a focus on end users, repeatable nature of projects, and integrated teams are found to be the main success factors. The findings of this study are expected to guide construction professionals in implementing innovative low-carbon practices in collaborative project environments. The proposed framework can be used to better understand the carbon-reduction process in other projects and other countries where different regulations and conditions prevail. [ABSTRACT FROM AUTHOR]