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This paper examines the continued growth in the use of underground space beneath cities and the widespread lack of significant and broad planning efforts for its use. The paper is drawn from the collective experience and prior research of the authors together with information exchanges afforded by the activities of the International Tunnelling and Underground Space Association's Committee on Underground Space (ITACUS). The particular focus of this paper is on sustainability issues related to urban underground space use including contribution to an environmentally sustainable and aesthetically acceptable landscape, anticipated structural longevity and the maintenance of opportunity for urban development by future generations. However, owing to their initial cost and permanent alteration of the underground environment, underground structures put a special emphasis on long-range planning which considers life-cycle cost-benefits and the selection of projects that offer the highest contribution to urban sustainability rather than a short-term fix to an individual need.

For multi-site organisations, informed decision making on capital investment aimed closing the energy efficiency gap, cutting carbon emissions and improving network performance across a global site base is a complex problem. This paper presents the systematic development and implementation of a novel methodology to reach optimal energy efficiency in multi-site organisations across their network whilst reducing carbon footprint. The methodology, a Global Energy Management System, is based on the following strategic pillars: (1) Site Characterization (2) Performance Evaluation via key performance indicators and energy benchmarking (3) Energy Strategy (4) Shared learnings and dissemination. These pillars are underpinned by essential foundations: (a) Global energy team and communication forum, (b) Knowledge base at site and global level, and (c) Corporate Energy Policy. The methodology culminates with a simplified, understandable, systematic, repeatable and scalable decision support framework addressing the complexities unique to decision-making on capital investments in global multi-site organisation. A case study is presented for a multi-national corporation in the life sciences industry. The proposed approach increased the visibility of energy and related carbon emissions issues and triggered unprecedented levels of funding and support for energy efficiency measures, leading to entering the energy efficiency continuous improvement journey towards optimal network performance.

Second-order sideband generation in a coherent-mechanical pumped optomechanical system is discussed, and the features of the coherent mechanical pump induced enhancement of second-order sideband generation are identified. We show that the coherent mechanical pump induced enhancement of second-order sideband generation exhibits an essential difference between the case of a weak control field and a strong control field. In the weak control field case, the efficiency of second-order sideband generation increases as the amplitude of the mechanical pump increases. In the strong control field case, the effect of optomechanically induced transparency occurs and increasing the amplitude of the mechanical pump does not always bring an enhancement of second-order sideband generation. The phase-dependent effect of the second-order sideband generation with a coherent mechanical pump is also discussed, and it is shown that the phase difference φ plays an important role in the process of second-order sideband generation.

Literature reviewed suggests energy maturity models are in their infancy in the energy management sector, with little practical guidance for their implementation in multi-site organisations. In addressing this gap, this paper presents the development and implementation of an Energy Management Maturity Model for multi-site industrial organisations with a global presence, considered as a fundamental step towards continuous improvement and optimal energy efficiency. The developed maturity model provides a global view of the overall network readiness for engaging in energy efficiency by adapting and enhancing existing 'site focused' maturity models to cater for multi-site industrial an organisation. The model enables two-way communication between global and local energy management teams; not only are the individual sites benchmark but the global energy management team gets feedback and a gap analysis on their performance from the network of sites perspective. The evaluation framework created around the maturity model supports automated prioritization of elements with larger deviations. In parallel it provides the global energy management team with direction on where the organisation needs to focus central efforts to support the sites. The maturity model enables the evaluation of key not technical aspects of energy management required for continuous improvement on a multi-site and global scale.