A Multidimensional Model for Building Energy Management José Miguel Castanheira Cavalheiro Thesis to obtain the Master of Science Degree in Information Systems and Computer Engineering Supervisor: Prof. Dr. Paulo Jorge Fernandes Carreira Examination Committee Chairperson: Prof. Dr. João Emílio Segurado Pavão Martins Supervisor: Prof. Dr. Paulo Jorge Fernandes Carreira Member of the Committee: Prof. Dr. Diogo Manuel Ribeiro Ferreira November 2015 ii “Difficulties mastered are opportunities won.” — Winston Churchill iii iv Acknowledgments Gostaria de agradecer ao meu orientador, Professor Paulo Carrreira, pela exigencia,ˆ pelo empenho demonstrado, e pelas cr´ıticas, comentarios,´ e sugestoes.˜ A todos aqueles que acompanharam o progresso desta dissertac¸ao,˜ e que contribu´ıram com cr´ıticas e sugestoes.˜ A` minha fam´ılia, em especial aos meus pais, a` minha irma,˜ e aos meus avos,´ por todo o apoio que sempre me deram, para que pudesse concluir com exitoˆ esta etapa. A todos os amigos que fiz durante o percurso no IST, e aos inumeros´ colegas com quem passei interminaveis´ horas a desenvolver projectos. Em particular, agradec¸o ao Alberto Carvalho, ao Joao˜ Murtinheira, a` Marta Baptista, ao Nuno Duarte, ao Nuno Salvador, e ao Sebastiao˜ Freire, pela forte entre-ajuda demonstrada e pelos momentos partilhados. Obrigado. v vi Resumo A organizac¸ao˜ dos dados e´ um aspecto crucial para gerir os dados relacionados com o consumo de energia dos edif´ıcios. Apesar da importanciaˆ do tema nao˜ existem propostos na literatura modelos de referenciaˆ para gestao˜ de dados de energia de edif´ıcios. Por esse motivo, esta tese propoe˜ um modelo de dados de referencia,ˆ desenvolvido de acordo com as melhores praticas´ de modelac¸ao˜ multidimen- sional, e melhorado iterativamente de acordo com as revisoes˜ de utilizadores experientes no dom´ınio da energia. A qualidade do modelo e´ tambem´ avaliada de acordo com metricas´ de complexidade, us- abilidade, e qualidade de desenho. Alem´ disso, e´ tambem´ desenvolvido um prototipo´ de um sistema de gestao˜ de energia com base no model proposto, sendo posteriormente validado com gestores de energia de diversas organizac¸oes.˜ O resultado e´ portanto um modelo multidimensional de elevada qual- idade, e que pode ser reutilizado para criar ou melhorar os modelos dos sistemas de gestao˜ de energia existentes. Palavras-chave: Gestao˜ de Energia, Medidor de energia, Armazem´ de dados, Apoio a` de- cisao,˜ Modelo multidimensional vii viii Abstract Data organization is a critical aspect in Building Energy Data Management. Yet, despite the impor- tance of the topic, no sound reference model for energy data has been proposed in the literature. This work proposes a reference data model developed according to standard multidimensional modelling methodologies and improved iteratively in review meetings with users (knowledgeable in the energy management domain). The quality of the model is evaluated according to complexity, usability, and design metrics. Moreover, a BEMS prototype is built upon our model proposal, and validated with expe- rienced energy managers. The end-result is a high-quality re-usable multidimensional data model that can be applied to create or improve on the data model designs of building energy management systems. Keywords: Energy Management, Energy Metering, Data Warehousing, Decision Support, Mul- tidimensional Model ix x Contents Acknowledgments..............................................v Resumo.................................................... vii Abstract.................................................... ix List of Tables................................................. xv List of Figures................................................. xvii Nomenclature................................................. xix Glossary.................................................... xix 1 Introduction 1 1.1 Problem Definition...........................................2 1.2 Methodology and Contributions...................................2 1.3 Document Structure..........................................3 2 Concepts 5 2.1 Decision Support Systems......................................5 2.2 Building Energy Management Systems..............................6 2.2.1 Architecture of Building Energy Management Systems.................7 2.2.2 User Characterization....................................8 2.2.3 Comparison between BEMSs and DSSs.........................8 2.3 DW for Energy Management.....................................9 2.3.1 Multidimensional Model for Energy Management....................9 2.3.2 The Energy Data Cube.................................... 10 2.3.3 Slowly Changing Dimensions................................ 11 2.4 Integration of Energy-Related Data Sources........................... 12 2.5 Energy Data Quality.......................................... 13 3 Related Work 15 3.1 Energy Information systems..................................... 15 3.2 Energy Management Systems Standards and Guides...................... 17 3.3 DW Models for Building Energy Management........................... 18 3.3.1 Multidimensional Model Proposals in Literature..................... 18 3.3.2 Energy Data Analysis Activities............................... 19 xi 3.4 Evaluation of Conceptual Models.................................. 19 3.5 Evaluation of Multidimensional Models............................... 20 3.6 Energy Data Visualization and Reporting............................. 22 3.7 Discussion................................................ 23 4 A Multidimensional Model Solution 25 4.1 Multidimensional Model Development............................... 25 4.1.1 Building Energy Management Related Data Sources.................. 26 4.1.2 Building Energy Management Business Processes................... 28 4.2 Multidimensional Model Solution Description........................... 29 4.2.1 Fact Table Design Choices................................. 30 4.2.2 Multiple Transaction Fact Tables.............................. 30 4.2.3 Multi-valued Dimensions................................... 31 4.2.4 Role-playing Dimensions................................... 32 4.2.5 Aggregate Fact Tables.................................... 33 4.2.6 Variable Depth Hierarchies and Hierarchy Bridges................... 34 5 Multidimensional Model Validation 35 5.1 Metrics and Metric Selection..................................... 35 5.2 Multidimensional Model Validation Methodology......................... 36 5.2.1 Workload Tests........................................ 37 5.2.2 End-User Review Sessions................................. 38 5.3 Metrics Evaluation Results...................................... 38 5.3.1 Structural and Cognitive Complexity Metric Results................... 38 5.3.2 Usability Metric Results................................... 39 5.3.3 Design Quality Metric Results................................ 40 5.4 Model Validation Findings...................................... 40 5.4.1 Workload Tests Findings................................... 41 5.4.2 User Review Sessions Findings.............................. 41 5.5 Discussion................................................ 41 6 BEMS Prototype Solution 43 6.1 BEMS Prototype Development Context.............................. 43 6.2 ETL Workflows Development..................................... 44 6.2.1 Choosing the Data Integration Tool............................. 44 6.2.2 Determing Systems-of-Record and Extraction Procedures.............. 44 6.2.3 Extracting Data from Sources................................ 45 6.2.4 Establishing Data Source Priorities............................ 46 6.2.5 Overcoming Data Quality Problems............................ 47 6.2.6 Determining Slowly Changing Dimensions........................ 52 xii 6.2.7 Designing the Integration Processes............................ 52 6.3 OLAP Web Server Architecture Overview............................. 54 6.4 Metadata Repository Overview................................... 54 6.5 Energy Management Web Applications.............................. 55 6.5.1 Application Use Case..................................... 56 6.5.2 Detailed Consumption Analysis Charts.......................... 58 6.5.3 Space Comparison Analysis Charts............................ 59 6.5.4 Year Comparison Analysis Charts............................. 59 6.5.5 Energy-related Factors Analysis Charts.......................... 60 6.5.6 A4 Occupation & Activities Analysis of a Lecture Room................ 60 6.5.7 Energy Costs Simulator................................... 61 6.5.8 Peak Load Analysis Charts................................. 61 6.6 Lessons Learned during BEMS Prototype Development.................... 62 6.7 BEMS Prototype Evaluation Context................................ 63 6.8 BEMS Prototype Evaluation Methodology............................. 64 6.9 BEMS Prototype Evaluation Results................................ 65 6.9.1 Usability and Performance Evaluation........................... 65 6.9.2 Evaluation of Energy Data Analysis Methods....................... 66 6.9.3 Evaluation of Individual Charts............................... 67 6.9.4 Discussion........................................... 68 7 Conclusions 69 7.1 Impact.................................................. 70 7.2 Future Work............................................... 70 Bibliography 73 A IST University Context Description 87 B Multidimensional Model Relational Schema 89 C ETL Workflows 93 C.1 ETL Workflows Dependencies Hierarchy............................. 93 C.2