A Multi-objective Harmony Search Algorithm for Optimal Energy and Environmental Refurbishment at District Level Scale

Nowadays municipalities are facing an increasing commitment regarding the energy and environmental performance of cities and districts. The multiple factors that characterize a district scenario, such as: refurbishment strategies’ selection, combination of passive, active and control measures, the surface to be refurbished and the generation systems to be substituted will highly influence the final impacts of the refurbishment solution. In order to answer this increasing demand and consider all above-mentioned district factors, municipalities need optimisation methods supporting the decision making process at district level scale when defining cost-effective refurbishment scenarios. Furthermore, the optimisation process should enable the evaluation of feasible solutions at district scale taking into account that each district and building has specific boundaries and barriers. Considering these needs, this paper presents a multi-objective approach allowing a simultaneous environmental and economic assessment of refurbishment scenarios at district scale. With the aim at demonstrating the effectiveness of the proposed approach, a real scenario of Gros district in the city of Donostia-San Sebastian (North of Spain) is presented. After analysing the baseline scenario in terms of energy performance, environmental and economic impacts, the multi-objective Harmony Search algorithm has been employed to assess the goal of reducing the environmental impacts in terms of Global Warming Potential (GWP) and minimizing the investment cost obtaining the best ranking of economic and environmental refurbishment scenarios for the Gros district.OptEEmAL project, Grant Agreement Number 68067

Two-Stage Multi-Objective Meta-Heuristics for Environmental and Cost-Optimal Energy Refurbishment at District Level

Energy efficiency and environmental performance optimization at the district level are following an upward trend mostly triggered by minimizing the Global Warming Potential (GWP) to 20% by 2020 and 40% by 2030 settled by the European Union (EU) compared with 1990 levels. This paper advances over the state of the art by proposing two novel multi-objective algorithms, named Non-dominated Sorting Genetic Algorithm (NSGA-II) and Multi-Objective Harmony Search (MOHS), aimed at achieving cost-effective energy refurbishment scenarios and allowing at district level the decision-making procedure. This challenge is not trivial since the optimisation process must provide feasible solutions for a simultaneous environmental and economic assessment at district scale taking into consideration highly demanding real-based constraints regarding district and buildings’ specific requirements. Consequently, in this paper, a two-stage optimization methodology is proposed in order to reduce the energy demand and fossil fuel consumption with an affordable investment cost at building level and minimize the total payback time while minimizing the GWP at district level. Aimed at demonstrating the effectiveness of the proposed two-stage multi-objective approaches, this work presents simulation results at two real district case studies in Donostia-San Sebastian (Spain) for which up to a 30% of reduction of GWP at district level is obtained for a Payback Time (PT) of 2–3 years.Part of this work has been developed from results obtained during the H2020 “Optimised Energy Efficient Design Platform for Refurbishment at District Level” (OptEEmAL) project, Grant No. 680676

OptEEmAL: Decision-Support Tool for the Design of Energy Retrofitting Projects at District Level

Designing energy retrofitting actions poses an elevated number of problems, as the definition of the baseline, selection of indicators to measure performance, modelling, setting objectives, etc. This is time-consuming and it can result in a number of inaccuracies, leading to inadequate decisions. While these problems are present at building level, they are multiplied at district level, where there are complex interactions to analyse, simulate and improve. OptEEmAL proposes a solution as a decision-support tool for the design of energy retrofitting projects at district level. Based on specific input data (IFC(s), CityGML, etc.), the platform will automatically simulate the baseline scenario and launch an optimisation process where a series of Energy Conservation Measures (ECMs) will be applied to this scenario. Its performance will be evaluated through a holistic set of indicators to obtain the best combination of ECMs that complies with user's objectives. A great reduction in time and higher accuracy in the models are experienced, since they are automatically created and checked. A subjective problem is transformed into a mathematical problem; it simplifies it and ensures a more robust decision-making. This paper will present a case where the platform has been tested.This research work has been partially funded by the European Commission though the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No 680676. All related information to the project is available at https://www.opteemal-project.eu

OptEEmAL: Decision-Support Tool for the Design of Energy Retrofitting Projects at District Level

Designing energy retrofitting actions poses an elevated number of problems, as the definition of the baseline, selection of indicators to measure performance, modelling, setting objectives, etc. This is time-consuming and it can result in a number of inaccuracies, leading to inadequate decisions. While these problems are present at building level, they are multiplied at district level, where there are complex interactions to analyse, simulate and improve. OptEEmAL proposes a solution as a decision-support tool for the design of energy retrofitting projects at district level. Based on specific input data (IFC(s), CityGML, etc.), the platform will automatically simulate the baseline scenario and launch an optimisation process where a series of Energy Conservation Measures (ECMs) will be applied to this scenario. Its performance will be evaluated through a holistic set of indicators to obtain the best combination of ECMs that complies with user's objectives. A great reduction in time and higher accuracy in the models are experienced, since they are automatically created and checked. A subjective problem is transformed into a mathematical problem; it simplifies it and ensures a more robust decision-making. This paper will present a case where the platform has been tested.This research work has been partially funded by the European Commission though the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No 680676. All related information to the project is available at https://www.opteemal-project.eu

An evaluation framework to support optimisation of scenarios for energy efficient retrofitting of buildings at the district level

Producción CientíficaEnergy-efficient retrofitting of buildings has become essential to achieve the environmental objectives of the European Union’s (EU) strategies towards reducing carbon emissions and energy dependency on fossil fuels. When tackling retrofitting projects, the issue of scale becomes essential as sometimes this can determine the sustainability of the project. Therefore, a comprehensive approach is essential to ensure effective decision-making. A platform has been designed within the EU funded OptEEmAL project to support stakeholders in this process, providing functionalities that can automatically model and evaluate candidate retrofitting alternatives considering their priorities, targets and boundary conditions. A core element of this platform is the evaluation framework deployed which implements a multi-criteria decision-making approach to transform the priorities of stakeholders into quantifiable weights used to compare the alternatives. As a result, more informed decisions can be made by the stakeholders through a comprehensive evaluation of the candidate retrofitting scenarios. This paper presents the approach followed to develop and integrate this evaluation framework within the platform as well as its validation in a controlled environment to ensure its effectiveness

Integration of prioritisation criteria in the design of energy efficient retrofitting projects at district scale: A case study

Producción CientíficaThe evident need for improving the existing building stock still suffers from important barriers, such as the fragmentation of the value chain, the lack of information regarding some solutions, and the lack of confidence with respect to energy savings, which prevent unlocking investments, and the difficult communication among stakeholders. Therefore, new processes based on exploiting the potential of existing and new tools are required. In this framework, the OptEEmAL project has developed a tool that integrates stakeholders, data and tools in order to ease the process of designing energy efficient retrofitting projects at building and district scale. This tool works around an optimisation framework in order to evaluate, compare and optimise candidate retrofitting scenarios against a set of indicators showing the performance of the district. This evaluation and optimisation method is based on aggregating indicators through transforming the priorities of stakeholders into a mathematical weighting scheme, which makes it possible to provide scenarios within their expectations. Therefore, the generation of these scenarios is driven by their design parameters, being thus flexible and adapted to their needs. This paper shows the implementation of this tool and specifically 3 different prioritisation schemes, analysing how they impact into the decision making process and selection of the retrofitting strategy

An Integrated Thermal Simulation & Generative Design Decision Support Framework for the Refurbishment or Replacement of Buildings: A Life Cycle Performance Optimisation Approach

The environmental performance of existing buildings can have a major role in achieving the CO2 reduction targets, set out by the UK government. In the UK, new buildings account for around 1% of the total building stock (annually), and predictions show that around 75% of the housing stock that will still remain in 2050 has already been built. Furthermore, while current building performance improvement efforts focus mainly on the operational performance of buildings, the environmental impact of the built environment is the result of processes that occur throughout their whole life-cycle (construction, usage and demolition). To achieve significant CO2 emission reductions in the built environment in an economically viable way, this thesis adopted the Life Cycle Carbon Footprint (LCCF) and Life Cycle Cost (LCC) analysis approaches, to enable a cross-comparison between multiple design alternatives and to identify the preferable design solution: the refurbishment of existing buildings or their replacement by new ones. In particular, this thesis has developed, tested and validated a computational framework that integrates life cycle performance protocols (EN 15978:2011 and BS ISO 15686-5), thermal simulation tools (EnergyPlus), mathematical optimisation (NSGA-II) and a designated building generative design programming (PLOOTO - Parametric Lay-Out Organisation generator) into a single computer application. The investigation was carried out using a comparative analysis of simulated case study buildings: a terrace-house, a bungalow and a block of flats. Results show that under the considered assumptions, the optimal refurbishment case studies achieved lower LCCF and LCC values than the replacements: The LCCF of the refurbishment scenarios was between 1,100-1,500 kgCO2e/m2 and their LCC 440-680 £/m2, compared to those of the replacements scenarios, who achieved between 1,220-1,850 kgCO2e/m2 and 550-890 £/m2. Furthermore, this research has found that optimising the performance of a typical London-based terrace house using a life cycle carbon approach reached 10% more savings in CO2 throughout its life, compared to targeting operational CO2 only. This means that complying with current UK regulations – which is currently only focused on the improvement of operational efficiencies – may result in buildings with poorer performance, in terms of their overall life cycle carbon footprint. This is associated to the difference in the analysis scope: while operational efficiencies only examine emissions due to heating and lighting within the building, the Life Cycle approach accounts for emissions that occur in other stages in the building’s life, e.g., emissions that are embodied within its structure, emissions during construction, maintenance and more. An important conclusion of this research is, therefore, that to reach significant reductions in emissions rates – a life-cycle approach should be adopted. More specifically, to achieve immediate reductions (on a 20-year scale) - refurbishments are generally preferable over replacements. It can, therefore, be concluded that there is a greater importance in incentivising re-use to achieve quicker emissions reductions. The research has shown that the integration of the various research tools in the proposed computational framework was successful in automating the analysis process. The comparative analysis approach was found to be useful in identifying the preferable design solution – the refurbishment of existing buildings or their replacement. Finally, the research sets out an extensive discussion in regard to the proposed computational framework, life cycle performance analysis and the potential benefits of refurbishments or replacements of existing buildings, in the context of the UK

Lost in optimisation of water distribution systems? A literature review of system design

This is the final version of the article. Available from MDPI via the DOI in this record.Optimisation of water distribution system design is a well-established research field, which has been extremely productive since the end of the 1980s. Its primary focus is to minimise the cost of a proposed pipe network infrastructure. This paper reviews in a systematic manner articles published over the past three decades, which are relevant to the design of new water distribution systems, and the strengthening, expansion and rehabilitation of existing water distribution systems, inclusive of design timing, parameter uncertainty, water quality, and operational considerations. It identifies trends and limits in the field, and provides future research directions. Exclusively, this review paper also contains comprehensive information from over one hundred and twenty publications in a tabular form, including optimisation model formulations, solution methodologies used, and other important details

Integration of Renewables in Power Systems by Multi-Energy System Interaction

This book focuses on the interaction between different energy vectors, that is, between electrical, thermal, gas, and transportation systems, with the purpose of optimizing the planning and operation of future energy systems. More and more renewable energy is integrated into the electrical system, and to optimize its usage and ensure that its full production can be hosted and utilized, the power system has to be controlled in a more flexible manner. In order not to overload the electrical distribution grids, the new large loads have to be controlled using demand response, perchance through a hierarchical control set-up where some controls are dependent on price signals from the spot and balancing markets. In addition, by performing local real-time control and coordination based on local voltage or system frequency measurements, the grid hosting limits are not violated

Multiple Criteria Analysis of the Life Cycle of the Built Environment

To design and achieve effective the life cycle of the built environment a complex analysis of its stages as well as stakeholders, their aims and potentialities is needed. The effect of micro, meso and macro environmental factors should also be taken into account. A thorough built environment’s life cycle (brief; design; raw material extraction, transport and processing; construction materials production and distribution; construction; use, repair and maintenance; demolition; disposal, reuse, or recycling) analysis is quite difficult to undertake, because a buildings and its environment are a complex system (technical, technological, economical, social, cultural, ecological, etc.), where all sub-systems influence the total efficiency performance and where the interdependence between sub-systems play a significant role. Various stakeholders (clients, users, architects, designers, utilities engineers, economists, contractors, maintenance engineers, built environment material manufacturers, suppliers, contractors, finansing institutions, local government, state and state institutions) are involved in the life cycle of the built environment, trying to satisfy their needs and affecting its efficiency. The level of the efficiency of the life cycle of the built environment depends on a number of variables, at three levels: micro, meso and macro level. The problem is how to define an efficient built environment life cycle when a lot of various parties are involved, the alternative project versions come to hundreds thousand and the efficiency changes with the alterations in the environment conditions and the constituent parts of the process in question. Moreover, the realization of some objectives seems more rational from the economic perspective thought from the other perspectives they have various significance. Therefore, it is considered that the efficiency of a built environment life cycle depends on the rationality of its stages as well as on the ability to satisfy the needs of the stakeholders and the rational character of environment conditions. Formalized presentation of the research shows how changes in the environment and the extent to which the goals pursued by various stakeholders are satisfied cause corresponding changes in the value and utility degree of a built environment life cycle. With this in mind, it is possible to solve the problem of optimization concerning satisfaction of the needs at reasonable expenditures. This requires the analysis of the built environment life cycle versions allowing to find an optimal combination of goals pursued and finances available. References to the most modern world scientific literature sources are presented in the monograph. The monograph is prepared for the researchers, MSc and PhD students of civil engineering, construction management and real estate development. The book may be useful for other researchers, MSc and PhD students of economics, management and other specialities. The edition was recommended by the Committe of Studies of VGTU Faculty of Civil Engineering. The publication of monograph was funded by European Social Fund according to project No. VP1-2.2-ŠMM-07-K-02-060 Development and Implementation of Joint Master’s Study Programme “Sustainable Development of the Built Environment”.The edition was recommended by the Committe of Studies of VGTU Faculty of Civil Engineering. The publication of monograph was funded by European Social Fund according to project No. VP1-2.2-ŠMM-07-K-02-060 Development and Implementation of Joint Master’s Study Programme “Sustainable Development of the Built Environment”