Imperial College London

Dr Salvador Acha

Faculty of EngineeringDepartment of Chemical Engineering

Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 3379salvador.acha Website CV

 
 
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Location

 

c410Roderic Hill BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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40 results found

Chakrabarti A, Proeglhoef R, Bustos-Turu G, Lambert R, Mariaud A, Acha S, Markides CN, Shah Net al., 2019, Optimisation and analysis of system integration between electric vehicles and UK decentralised energy schemes, Energy, Vol: 176, Pages: 805-815, ISSN: 0360-5442

Although district heat network schemes provide a pragmatic solution for reducing the environmental impact of urban energy systems, there are additional benefits that could arise from servicing electric vehicles. Using the electricity generated on-site to power electric vehicles can make district heating networks more economically feasible, while also increasing environmental benefits. This paper explores the potential integration of electric vehicle charging into large-scale district heating networks with the aim of increasing the value of the generated electricity and thereby improving the financial feasibility of such systems. A modelling approach is presented composed of a diverse range of distributed technologies that considers residential and commercial electric vehicle charging demands via agent-based modelling. An existing district heating network system in London was taken as a case study. The energy system was modelled as a mixed integer linear program and optimised for either profit maximisation or carbon dioxide emissions minimisation. Commercial electric vehicles provided the best alternative to increase revenue streams by about 11% against the current system configuration with emissions effectively unchanged. The research indicates that district heating network systems need to carefully analyse opportunities for transport electrification in order to improve the integration, and sustainability, of urban energy systems.

JOURNAL ARTICLE

Acha Izquierdo S, Shah N, Howard B, Polak Jet al., Implicit Sensing of Building Occupancy Count with Information and Communication Technology Data Sets Building and Environment, Building and Environment

JOURNAL ARTICLE

Efstratiadi M, Acha Izquierdo S, Shah N, Markides Cet al., 2019, Analysis of a closed-loop water-cooled refrigeration system in the food retail industry: A UK case study, Energy, ISSN: 0360-5442

Refrigeration in supermarkets accounts between 30% and 60% of total electricity demand in UK stores. The aim of this study is to conduct a pre-feasibility analysis of whether the use of a water-cooled configuration rejecting heat to the soil can improve the overall cooling performance of commercial refrigeration systems against air-cooled designs. In this work, a model simulating the operation of an existing refrigeration system is presented and validated against field data measurements taken from a supermarket. The examined system is used as a baseline and then modified to evaluate the impact of installing a water-cooled gas cooler. Results indicate that the use of water-cooled gas coolers has the potential to reduce electrical consumption of refrigeration systems by up to a factor of 5 when external temperatures are high. Overall, annual operation indicates the water-cooled alternative uses 3% less electricity than the air-cooled approach. A hybrid system is also considered consisting of coupled air-cooled and water-cooled units operating in parallel, for which an energy reduction of 6% is obtained compared against the baseline system. An economic evaluation of these systems shows promising results with a payback period of about 5 years for systems installed in new stores, although retrofits are costlier.

JOURNAL ARTICLE

O'Dwyer E, Pan I, Acha S, Shah Net al., 2019, Smart energy systems for sustainable smart cities: Current developments, trends and future directions, APPLIED ENERGY, Vol: 237, Pages: 581-597, ISSN: 0306-2619

JOURNAL ARTICLE

Georgiou S, Acha S, Shah N, Markides CNet al., 2018, A generic tool for quantifying the energy requirements of glasshouse food production, JOURNAL OF CLEANER PRODUCTION, Vol: 191, Pages: 384-399, ISSN: 0959-6526

JOURNAL ARTICLE

Acha S, Mariaud A, Shah N, Markides CNet al., 2018, Optimal design and operation of distributed low-carbon energy technologies in commercial buildings, ENERGY, Vol: 142, Pages: 578-591, ISSN: 0360-5442

JOURNAL ARTICLE

Delangle A, Lambert RSC, Shah N, Acha S, Markides CNet al., 2017, Modelling and optimising the marginal expansion of an existing district heating network, ENERGY, Vol: 140, Pages: 209-223, ISSN: 0360-5442

JOURNAL ARTICLE

Mariaud A, Acha S, Ekins-Daukes N, Shah N, Markides CNet al., 2017, Integrated optimisation of photovoltaic and battery storage systems for UK commercial buildings, APPLIED ENERGY, Vol: 199, Pages: 466-478, ISSN: 0306-2619

JOURNAL ARTICLE

Howard BN, acha Izquierdo S, polak J, shah Net al., Measuring building occupancy through ICT data streams, ECEEE SUMMER STUDY PROCEEDINGS

CONFERENCE PAPER

Efstratiadi M-A, Acha S, Shah N, Markides CNet al., 2017, Analysis of Closed Loop Water-Cooled Refrigeration Systems for the Food Retail Industry: A UK Case Study, ASHRAE Annual Conference, Publisher: AMER SOC HEATING, REFRIGERATING AND AIR-CONDITIONING ENGS, ISSN: 2578-5257

CONFERENCE PAPER

Acha S, Mariaud A, Shah N, Markides CNet al., 2017, Optimal design and operation of low-carbon energy technologies in commercial buildings

© 2017 IMEKO Non-domestic buildings are large energy consumers and present many opportunities with which to enhance the way they produce and consume electricity, heating and cooling. If energy system integration is feasible, this can lead to significant reductions in energy use and emissions associated with building operations. Due to their diverse energy requirements, a broad range of technologies in flexible solutions need to be evaluated to identify the best alternative. This paper presents an integrated energy-systems model that optimizes the selection and operation of distributed technologies for commercial buildings. The framework consists of a comprehensive technology database, half-hourly electricity cost profiles, conventional fuel costs and building features. This data is applied to a mixed-integer linear programming model that optimizes the design and operation of installed technologies based on a range of financial and environmental criteria. The model aims to guide decision makers in making attractive investments that are technically feasible and environmentally sound. A case study of a food distribution centre in the UK is presented to illustrate the economic and environmental benefits the proposed integrated energy systems model could bring against a business as usual (BaU) approach. The technology portfolio considered in the case study includes combined heat and power (CHP) and organic Rankine cycle (ORC) engines, absorption chillers, photovoltaic (PV) panels, and battery systems. The results clearly illustrate the different outcomes and trade-offs that can emerge when stakeholders champion different technologies instead of making an exhaustive assessment. Overall, the model provides meaningful insights that can allow stakeholders to make well informed investment decisions when it comes to the optimal configuration and operation of energy technologies in commercial buildings.

CONFERENCE PAPER

Dahmm H, Bustos-Turu G, Acha S, Shah Net al., 2017, Techno-economic analysis and trade-offs of cooperative community energy planning schemes in the UK

© 2017 IMEKO Community Energy (CE) is the ownership of distributed energy resources by local communities. this paper describes a modelling framework for how communities can realize new opportunities through cooperation. The model disaggregates a community into sectors, having unique combinations of energy profiles, financial conditions, and available technologies. A modified Nash Bargaining technique was used to optimize the selection and operation of boiler, heat pump and CHP technologies, while also managing the exchange of energy vectors within the community; sectors cooperated first by exchanging electricity generation, exchanging heat, and then exchanging electricity and heat together. This approach adds to the literature by comparing forms of energy integration while considering diverse community interests. A case study was developed from London residential data, combined with profiles of five non-residential sectors. Results show that the exchange of electricity or heat can increase CO2 mitigation relative to independent action, but exchanging electricity and heat together magnifies the possible mitigation. Economic benefits vary between sectors and scenarios, but exchanging electricity and heat together maximizes the objective. Cooperation increases community resilience to reductions in government support, and increasing existing subsidies might reduce the incentive to cooperate. Future work should consider business plans for realizing environmental and economic benefits.

CONFERENCE PAPER

Georgiou S, Acha S, Shah N, Markides CNet al., 2017, Assessing, Benchmarking and Analyzing Heating and Cooling Requirements for Glasshouse Food Production: A Design and Operation Modelling Framework, 1st International Conference on Sustainable Energy and Resource Use in Food Chains (ICFES) / Symposium on Heat Recovery and Efficient Conversion and Utilisation of Waste Heat, Publisher: ELSEVIER SCIENCE BV, Pages: 164-172, ISSN: 1876-6102

CONFERENCE PAPER

Alvarado DC, Acha S, Shah N, Markides CNet al., 2016, A Technology Selection and Operation (TSO) optimisation model for distributed energy systems: Mathematical formulation and case study, APPLIED ENERGY, Vol: 180, Pages: 491-503, ISSN: 0306-2619

JOURNAL ARTICLE

Acha Izquierdo S, Shah N, 2016, Re-commissioning Energy Conservation Measures in Supermarkets: An UK Case Study, CLIMA 2016, Publisher: Aalborg University, Department of Civil Engineering

Considering the UK’s ambitious carbon emission reduction target (i.e. reducingCO2e emissions by 80% below 1990 levels by 2050), it is evident that energyconservation measures in food retail buildings can substantially contribute inmeeting this goal. Supermarket buildings in particular are complex energy systemsthat require careful study to make sure they perform in a sensible manner. Retailpressure on quick store delivery makes commissioning teams prone to mistakes andtherefore, despite stores being newly built or refurbished, their systems are notideally set up. This circumstance makes buildings underperform by excessivelyconsuming energy which is a detriment in terms of costs and carbon emissions. Theobjective of this paper is to disseminate the energy savings that can come from lowcost re-commissioning measures linked to best operating practices; this is achievedby gathering insights from the monitoring of refrigeration, HVAC, and lightingsystems. A case study in a 3,300 m2 UK supermarket showcases the energyperformance of these systems before and after measures are implemented. The trialsconducted have the feature of being holistic by working closely with store staff andcontractors. Results show store energy use in Year 2 improved by 20% against itsbenchmark (Year 1); consequently reducing the carbon footprint and energy bills ofthe building. Furthermore, the learning’s are transferable and have quick paybackperiods; thus making clear a large potential exists in reducing energy bills ofretailers while simultaneously contributing to carbon mitigation in the UK.

CONFERENCE PAPER

Acha S, Du Y, Shah N, 2016, Enhancing energy efficiency in supermarket refrigeration systems through a robust energy performance indicator, INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID, Vol: 64, Pages: 40-50, ISSN: 0140-7007

JOURNAL ARTICLE

Bustos-Turu G, van Dam KH, Acha S, Markides CN, Shah Net al., 2016, Simulating residential electricity and heat demand in urban areas using an agent-based modelling approach, IEEE International Energy Conference (ENERGYCON), Publisher: IEEE, ISSN: 2164-4322

CONFERENCE PAPER

Bustos G, Guo M, van Dam KH, Acha S, Shah Net al., 2016, Incorporating life cycle assessment indicators into optimal electric vehicle charging strategies: An integrated modelling approach, Editors: Kravanja, Bogataj, Publisher: ELSEVIER SCIENCE BV, Pages: 241-246

BOOK CHAPTER

Cedillos D, Acha S, Shah N, 2016, Optimal Technology Selection and Operation of Bio-methane CHP Units for Commercial Buildings, ASHARE Annual Conference, Publisher: AMER SOC HEATING, REFRIGERATING AND AIR-CONDITIONING ENGS, ISSN: 2578-5257

CONFERENCE PAPER

Dalpane P, Acha S, Shah N, 2016, Operational and Economic Analysis of GSHP Coupled with Refrigeration Systems in UK Supermarkets, ASHARE Annual Conference, Publisher: AMER SOC HEATING, REFRIGERATING AND AIR-CONDITIONING ENGS, ISSN: 2578-5257

CONFERENCE PAPER

Acha S, Bustos-Turu G, Shah N, 2016, Modelling Real-Time Pricing of Electricity for Energy Conservation Measures in the UK Commercial Sector, IEEE International Energy Conference (ENERGYCON), Publisher: IEEE, ISSN: 2164-4322

CONFERENCE PAPER

Caritte V, Acha S, Shah N, 2015, Enhancing Corporate Environmental Performance Through Reporting and Roadmaps, BUSINESS STRATEGY AND THE ENVIRONMENT, Vol: 24, Pages: 289-308, ISSN: 0964-4733

JOURNAL ARTICLE

Acha Izquierdo S, Loh C, Noye S, Shah Net al., 2015, Retail Building Thermal Efficiency Improvement Through an Enhanced Re-Commissioning Framework, 2015 ASHRAE Annual Conference, Publisher: ASHRAE, ISSN: 1088-8586

End-use energy efficiency is recognized as a predominant contributor to achieve UK carbon reduction target that is still far from reach today. Theopportunity in retail buildings is apparent, especially supermarkets that account for 4 MtCO2e of total UK carbon footprint. This paper outlinesan enhanced re-commissioning (Re-Cx) framework that aims to mitigate supermarkets with poor energy performance, known as “cold-stores”. Theframework delivers a holistic approach with four critical strategies – Identification, Monitoring, Rectification and Prevention in sustainingsupermarket thermal efficiency throughout its operational lifecycle. This includes a comprehensive store characterization to identify “cold-store”, keyperformance indicators (KPIs) proposal for supermarket thermal efficiency monitoring, a cost-effective fault indication flowchart development for“cold-store” rectification, and the introduction of a novel Re-Cx and maintenance integration approach to prevent “cold-store” in a sustainablemanner. A case study is carried out on 350 stores from one of the biggest UK supermarket chains. Seven “cold-stores” are identified from thecomprehensive store benchmarking and characterization analysis. These results are also validated through the proposed KPIs. Moreover, acomparison between EnergyStar Re-Cx strategies and the supermarket maintenance procedures found 80% of the Re-Cx measures could beintegrated into the maintenance activities. This ascertains the feasibility of the suggested integration approach. In a nutshell, this framework bringsa new perception to retail Re-Cx regime, which can be implemented to effectively identify, monitor, rectify and prevent “cold-stores”.

CONFERENCE PAPER

Acha Izquierdo S, Shah N, Bos J, Cost effective low carbon store analysis and replication, CIBSE Technical Symposium 2015

This paper explores how low carbon buildings can be easily and cost effectivelyreplicated for a commercial retailer. The analysis investigates zero carbonsupermarkets using bio-methane combined heat and power (CHP). Results showthat CHP & district heating is the most cost effective design for a sustainablesupermarket. However, its implementation depends greatly on third parties and thusis not easy to replicate. The second best alternative is to use a CHP coupled with anOrganic Rankine Cycle (ORC) when the buildings heat-to-power ratio is below 0.5.Otherwise, a CHP with no heat recovery solution is deemed best. Overall, the mostcost effective ZCS projects are the ones implemented in stores with a high heat-topowerratio, high energy intensities and large surface floor area.

CONFERENCE PAPER

Andrianopoulos E, Acha S, Shah N, 2015, Achieving net zero carbon performance in a commercial building by aligning technical and policy alternatives - An UK case study

Quantifying a detailed inventory of carbon emissions attributed to a retail building is of vital importance to minimize (or offset) their environmental impact. However, quantifying the environmental impact of a commercial building's operation has attracted great controversy regarding both the carbon fields considered within the building's operational boundaries and the different responsibility levels among participants. This paper details a robust framework on how businesses operating under UK policy can measure the operational carbon performance attributed to their buildings. Furthermore, the paper investigates how the quantified emissions can be offset in order to reach net zero carbon operational performance. The analysis is structured in three levels and its applicability is showcased through an industry-sourced example of a supermarket building. The first level aims to classify building emissions according to their sources namely electricity consumption, on-site fuel burning, water supply, transport operations and waste management & disposal. The developed carbon fields' analysis technique treats a commercial building as an on-going energy consuming system where different operations (e.g. transport activities) contribute to the building's commercial use as well as to its operational carbon footprint. In the second level, the study compares a food store's carbon footprint across different supply and operation scenarios in order to analyse how each sector can influence emissions. In the third stage, the research details the carbon off-setting achieved by installing a bioenergy combined heat and power (CHP) unit in its premises and thus achieving net zero carbon performance. Results illustrate the environmental benefits for different CHP capacity solutions. These results show how urban cogeneration plants can de-carbonise UK buildings. However, the UK carbon accounting framework is still evolving and therefore is constantly subject to regulatory changes. Conse

CONFERENCE PAPER

Bustos-Turu G, van Dam KH, Acha S, Shah Net al., 2014, Estimating Plug-in Electric Vehicle Demand Flexibility through an Agent-Based Simulation Model, 5th IEEE PES Innovative Smart Grid Technologies Conference Europe (ISGT Europe), Publisher: IEEE, ISSN: 2165-4816

CONFERENCE PAPER

Acha S, Van Dam KH, Shah N, 2013, Spatial and temporal electric vehicle demand forecasting in central London

If electricity infrastructures are to make the most of electric vehicle (EV) technology it is paramount to understand how mobility can enhance the management of assets and the delivery of energy. This research builds on a proof of concept model that focuses on simulating EV movements in urban environments which serve to forecast EV loads in the networks. Having performed this analysis for a test urban environment, this paper details a case study for London using an activity-based model to make predictions of EV movements which can be validated against measured transport data. Results illustrate how optimal EV charging can impact the load profiles of two areas in central London - St. John's Wood & Marylebone/Mayfair. Transport data highlights the load flexibility a fleet of EVs can have on a daily basis in one of the most stressed networks in the world, while an optimal power flow manages the best times of the day to charge the EVs. This study presents valuable information that can help in begin addressing pressing infrastructure issues such as charging point planning and network control reinforcement.

CONFERENCE PAPER

Mavromatidis G, Acha S, Shah N, 2013, Diagnostic tools of energy performance for supermarkets using Artificial Neural Network algorithms, ENERGY AND BUILDINGS, Vol: 62, Pages: 304-314, ISSN: 0378-7788

JOURNAL ARTICLE

Keirstead J, Shah N, 2013, Urban Energy Systems: An Integrated Approach, Publisher: Routledge, ISBN: 9780415529020

Energy demands of cities need to be met more sustainably. This book analyses the technical and social systems that satisfy these needs and asks how methods can be put into practice to achieve this.

BOOK

Acha S, Mavromatidis G, Caritte V, Shah Net al., 2013, Effective low-cost energy saving strategies in supermarkets: An UK case study

Supermarket buildings are complex energy systems that require careful study to make sure they perform in a sensible manner. The retail pressure of delivering stores in a short time makes engineering commissioning teams prone to mistakes and therefore, despite stores being newly built and carefully designed, their systems are not ideally set up; thus making the building underperform from day one. Consequently, energy savings are within easy reach if an effort is made to re-evaluate stores shortly after their opening date. This paper focuses on how adequate monitoring and good housekeeping can lead to effective energy saving strategies for a better management of services such as lighting, refrigeration, heating and ventilation. Additionally, a focused effort in curtailing energy use in supermarkets can also seriously reduce operational carbon related emissions; an ever-growing concern for retailers in an environment where sustainability practice is highly valued by consumers. A case study of a 35,000 ft2 supermarket located in the south-east of England serves as a vehicle to present and quantify effective, low-cost energy saving strategies. Extensive monitoring capabilities allow us to set a benchmark for all systems which then serves to assess the effectiveness of trials performed. Trials consist of: a) enhancing the dimming capabilities of the lighting system by improving sensor location and code, b) improving settings of fans and boiler system that reduce heating and ventilation requirements, and c) advocating the proper use of night-blinds in cabinets coupled with suction optimization of compressors that save energy use in the refrigeration system. All of these live trials have the feature of working closely with store staff and management, specialised contractors and academics. The synergy of parties allows the energy trials to succeed since aside from having solid technical foundations they have the full support from the people that work day in and day out in th

CONFERENCE PAPER

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