Energieffektivisering börjar bli ett eftersträvande mål runtom i världen. Detta grundar sig i att energiförbrukningen för byggnader uppgår till ca 40 % globalt, en siffra som man vill få ner. Men att uppnå en energieffektiv byggnad är inte lätt. Detta kan göras på många och olika sätt. Ett av dem är att energieffektivisera fönstren, som är en byggnads svagaste punkt pga dess höga U-värde. Val av fönster är inte lätt, och det finns ett flertal alternativ att välja bland. I kalla klimat som Sverige söker man fönster med lågt U-värde och högt g-värde, samt en hög avskärmningsfaktor. I varmare länder vill man också ha ett lågt U-värde hos fönster men fokusen ligger främst på en låg avskärmningsfaktor. Syftet med uppsatsen var att hitta de mest energieffektiva fönstren, oavsett kostnad, för byggnader som befinner sig i länder med kallare klimat. Det var också av vikt att få veta lönsamheten för fönstren i fråga, därför har även kostnadsfrågor belysts. Metodvalen var informationssökning i olika databaser och litteratur samt att olika företag inom fönsterbranschen kontaktades, vilket ledde till att relevant och önskvärd information erhölls. Därefter fortskred arbetet genom kalkyleringar för energibalansen och lönsamheten. Vacuumfönster, aerogelfönster samt kromogena fönster hör till framtida fönster som kan tillföra positiva inverkan på energibalansen för byggnader. Men dessa fönster är i nuläget inte helt färdigutvecklade, fast har potential att bli världsledande. Vacuumfönster och kromogena fönster är i nuläget bättre lämpade för varmare klimat. Lyckas man komma längre med deras nutida utveckling är det inte omöjligt att anpassa de för kallare klimat. Aerogelfönster ger mest energibesparing vid byte av fönster, men pga vissa optiska egenskaper och komplicerad tillverkning av produkten är den i nuläget inte optimal vid ett fönsterbyte. De framtida fönstren är ej heller ekonomiskt försvarbara, det finns i dagsläget kommersiella energieffektiva fönster som är billigare att införskaffa och ger ett ansenligt bra resultat för en byggnads energibalans. / Energy optimization is starting to be a pursued worldwide main goal. This is based on the global energy consumption that occurs in buildings, which is about 40 percent. There is no doubt that this value needs to be lowered. But to achieve an energy efficient building is not easy. Although, this can be done in many and different ways. One of them is to optimize the windows, which is a buildings weakest point due to its high U-value.The choice of windows can be a harsh decision, there’s plenty of windows to choose among. In heating dominated climates, as the one in Sweden, it is necessary to choose windows with low U-values and high g-values, also a high solar heat gain coefficient/shading coefficient is required. A window with a low U-value is also important in cooling dominated climates but the main focus is instead on a low shading coefficient, which is not the case in this thesis. The purpose is to find the most energy efficient window that lowers the need for active heating in buildings, and also reveal and discuss the cost issues for the chosen windows.By searching in scientific databases and contacting companies active in the window industry the desired information was obtained. Calculations including the energy balance and present value were made, which gave an indication of the profitability for the different windows. Vacuum, aerogel and chromogenic window are examples of future windows which can have a positive impact on the energy balance in buildings. Yet these windows are currently not fully developed, but have potential to be highly valuable types of windows. Vacuum and chromogenic windows are better suited for cooling dominated climates. However if the development succeed where a big progress will be made it will not be impossible to suit them for heating dominated climates too. Aerogel windows have the best impact on the energy savings when replacing windows, but due to some optical attributes and a complicated manufacturing of the product aerogel windows are currently not an optimal choice for window replacement. The future windows isn’t either economically viable. For now, there are other commercially energy efficient windows that are cheaper to purchase. They also show an acceptable good result on the energy balance for a building.

Energy has always been the dominant driving force for the socio-economic development of mankind. Nowadays, the global energy system is highly depended on fossil fuels. A great share of the final energy consumption, over 40%, in the EU-27 is consumed by the existing building stock whereas dwellings account for 66.62% of this. Thus, the need to increase the energy performance of dwellings is an important instrument in the efforts to lessen Europe’s energy dependency. In order to define measures to increase the energy performance of dwellings a deeper understanding of their characteristics should be gained. Unfortunately, in Cyprus there is a gap in knowledge on this aspect. In this thesis the characteristics of the dwellings in Cyprus are defined through a sample of 500 dwellings. The results revealed that more than 80% of dwellings in Cyprus do not have thermal insulation installed on their envelope. From this it is clear that the definition of the optimum thermal insulation material to be applied in dwellings is very important. Thus, the commercially available thermal insulation materials and topologies used in Cyprus were reviewed and defined through a market survey and the typical dwelling was modelled. The effect of the application of thermal insulation to its energy behaviour was simulated using TRNSYS. This resulted in the definition of the optimum thermal insulation materials and topologies to be applied in both new and existing dwellings. Accordingly, the application of advanced commercially available materials such as Phase Change Materials (PCM) to the envelope of the typical dwelling was investigated. The energy savings achieved by the addition of a PCM layer on the envelope of the typical dwelling was found to be 28.6%. The optimum PCM case was also combined with the optimum thermal insulation combination and an energy saving of 68% was predicted. The incorporation of Renewable Energy Sources (RES) to the typical dwelling was also simulated and studied. Specifically, two types of standalone RES systems were initially evaluated; a solely photovoltaic (PV) system and a hybrid PV-Wind system. The results showed that the solely PV system is a much better option due to the very high solar potential of Cyprus in comparison to the poor wind profile of the island. Subsequently, a grid-connected PV system was also evaluated and the results showed that when a RES system is grid-connected the cost of the system is reduced to half of that of the standalone cases. This research has revealed that the optimum topology combinations to be applied in both new and existing dwellings in Cyprus is thermal insulation plaster or thermal insulation bricks (only for new dwellings) on the external walls combined with expanded polystyrene on the roof. These results will provide valuable information that will assist both engineers and architects in the efficient design of dwellings in Cyprus. The investigation of the application of macroencapsulated PCM showed that these materials are not yet an economically viable solution for application in Cyprus The findings also show that a solely PV system is the optimum RES system to be applied in Cyprus especially when it is grid-connected. The findings of this project are useful for individuals, house builders and designers as well as policy makers for the design of energy saving subsidy schemes.

Thermal resistance per unit thickness for Vacuum Insulation Panel (VIP) is 5 to 10 times higher than conventional insulation materials. This makes VIP an attractive option for retrofitting exterior building envelopes. Insulation can be added in an exterior wall either on the interior side, exterior side or in the available stud cavity. VIP has high vapor diffusion resistance factor and could lead to moisture management risk in the wall layers because of the steep temperature gradient in the wall generated due to very high thermal resistance of VIP. VIP is a relatively new insulation material for building envelope construction, thus the hygrothermal or moisture management performance of VIP-insulated exterior building envelopes need to be critically analyzed before its application. This study aims to evaluate the moisture management risk associated with wood-frame stucco-cladded exterior walls retrofitted with VIP using a 2-D hygrothermal simulation tool WUFI-2D. Eight North American locations were considered, based on Moisture Index (MI) which varied between 0.13 and 1.17, and two different indoor hygrothermal loading conditions as prescribed by the ASHRAE 160P and EN 13788, respectively. The outputs from hygrothermal simulations (water content, relative humidity and temperature) were critically analysed and expressed further using freeze-thaw cycles and RHT indices. The results show that the appropriately designed VIP retrofitted walls can have superior moisture management performance as compared to conventional stucco-cladded wall. / Graduate

Efficient energy use is primarily for any sensor networks to function for a longer time period. There have been many efficient schemes with various progress levels proposed by many researchers. Yet, there still more improvements are needed. This thesis is an attempt to make wireless sensor networks with further efficient on energy usage in the network with respect to rate of delivery of the messages. In sensor network architecture radio, sensing and actuators have influence over the power consumption in the entire network. While listening as well as transmitting, energy is consumed by the radio. However, if by reducing listening times or by reducing the number of messages transmitting would reduce the energy consumption. But, in real time scenario with critical information sensing network leads to information loss. To overcome this an adaptive routing technique should be considered. So, that it focuses on saving energy in a much more sophisticated way without reducing the performance of the sensing network transmitting and receiving functionalities. This thesis tackles on parts of the energy efficiency problem in a wireless sensor network and improving delivery rate of messages. To achieve this a routing technique is proposed. In this method, switching between two routing paths are considered and the switching decision taken by the server based on messages delivered comparative previous time intervals. The goal is to get maximum network life time without degrading the number of messages at the server. In this work some conventional routing methods are considered for implementing an approach. This approach is by implementing a shortest path, Gradient based energy routing algorithm and an observer component to control switching between paths. Further, controlled switching done by observer compared to normal initial switch rule. Evaluations are done in a simulation environment and results show improvement in network lifetime in a much more balanced way.

Security is a primary concern in this era of pervasive computing. Hardware based security mechanisms facilitate the construction of trustworthy secure systems; however, existing hardware security approaches require modifications to the micro-architecture of the processor and such changes are extremely time consuming and expensive to test and implement. Additionally, they incorporate cryptographic security mechanisms that are computationally intensive and account for excessive energy consumption, which significantly degrades the performance of the system. In this dissertation, I explore the domain of hardware based security approaches with an objective to overcome the issues that impede their usability. I have proposed viable solutions to successfully test and implement hardware security mechanisms in real world computing systems. Moreover, with an emphasis on cryptographic memory integrity verification technique and embedded systems as the target application, I have presented energy efficient architectures that considerably reduce the energy consumption of the security mechanisms, thereby improving the performance of the system. The detailed simulation results show that the average energy savings are in the range of 36% to 99% during the memory integrity verification phase, whereas the total power savings of the entire embedded processor are approximately 57%.

Dans cette thèse, nous étudions divers problèmes dont l'objectif est de gérer la croissance d'internet plus efficacement. En effet celle-ci est très vive : 41% pour le pic en 2012. Afin de répondre aux défis posés par cette évolution aux divers acteurs du réseau, des protocoles de gestion et de communication plus intelligents sont nécessaires. Les protocoles de l'Internet furent conçus, point à point. Or, la part de la diffusion de média dans le trafic est prépondérante et en hausse tendancielle, et des projections indiquent qu'en 2016 80-90% du trafic sera engendré par de la diffusion vidéo. Cette divergence entraîne des inefficacités car les données parcourent plusieurs fois le réseau. Dans cette thèse, nous étudions comment tempérer cette inefficacité. Nos contributions sont organisées selon les couches et les phases de déploiement du réseau. Nous étudions le placement de caches lors de la conception du réseau. Ensuite, pour la gestion d'un réseau, nous regardons quand placer des appareils en veille, en utilisant un mécanisme de cache et en coopération avec des réseaux de distribution. Puis, au niveau de la couche application, nous étudions un problème de maintenance d'arbres équilibrés pour la diffusion de média. Enfin, nous analysons la probabilité de survie de données dans un système de sauvegarde distribuée. Notre travail se fonde à la fois sur des méthodes théoriques (Chaînes de Markov, Programmation Linéaire), mais aussi sur des outils empiriques tels que la simulation et l'expérimentation. / In this thesis we study multiple approaches to efficiently accommodating for the future growth of the Internet. The exponential growth of Internet traffic, reported to be as high as 41% in peak throughput in 2012 alone, continues to pose challenges to all interested parties. Therefore, to accommodate the growth, smart management and communication protocols are needed. The basic protocols of the Internet are point-to-point in nature. However, the traffic is largely broadcasting, with projections stating that as much as 80-90% of it will be video by 2016. This discrepancy leads to inefficiency, where multiple copies of essentially the same messages travel in parallel through the same links. In this thesis we study multiple approaches to mitigating this inefficiency. The contributions are organized by layers and phases of the network life. We look into optimal cache provisioning during network design. Next, we move to managing an existing network. We look into putting devices to sleep mode, using caching and cooperation with Content Distribution Networks. In the application layer, we look into maintaining balanced trees for media broadcasting. Finally, we analyze data survivability in a distributed backup system, which can reduce network traffic by putting the backups closer to the client than if using a data center. Our work is based on both theoretical methods, like Markov chains and linear programming, as well as empirical tools, like simulation and experimentation.

This paper presents an analytical framework of governing innovative building practices at a municipal level based on conclusions drawn from the Strategic Niche Management (SNM) approach. The analytical framework viewed the Village House Block demonstration project and EnSURE transnational research collaboration as important facilitators to create the necessary conditions for governing innovation during the renovation of the outdated building stock located in the 3rd District Municipality of Budapest, Hungary. These necessary conditions were articulated in accordance with the three internal processes (the articulation of expectations and visions, the building of social networks and the fostering of learning processes) defined by SNM research. Additionally, the Sustainable Energy Action Plan (SEAP) methodology was considered as a viable tool to guide energy efficient urban development in the district. It was found in this research that the Village House Block renovation represented a local technological niche project during which the feasibility of active and passive building technology was tested. This study revealed that the necessary conditions for governing innovation were present in this project. EnSURE was a collaborative research project which did not represent a clear example of technological niche development. It was defined as an important initiative to collect and accumulate knowledge and experiences from local niche projects to create a strategic tool for supporting energy efficient urban development at the municipal level. In this case study, the tool was the Sustainable Energy Action Plan. Overall, it was found that the necessary conditions did not only appear in technological niche projects, such as the Village House Block demonstration project but also in other types of projects, such as EnSURE. Furthermore, it could be argued that the governance of innovative approaches requires an operational framework in which different projects are managed to create these necessary conditions for local technological niche development. At global niche-level, it was revealed that the SEAP or other action plan methodologies could offer a tool to utilise experiences gained from local niches to create an energy efficient urban development strategy. In practice, it was shown that the importance of experimentation with new technologies and the governance of innovation on a strategic way still in its infancy in the 3rd District.

The idea for this project is to design an eco-village on a property in Glimåkra in Skåne of southern Sweden, which is owned by the municipality of Östra Göinge. All of the designs in this eco-village would be built with materials that will benefit the environment and the people living there. This community would also have low energy consumption and will achieve the Miljöbyggnad Gold certification. Initially, a few eco-villages in Sweden were studied and reviewed in order to get more experience in the subject and to find inspiration. Three different types of housing units were chosen to be compared to one another to determine the two most efficient candidates.  Two townhouses, two duplexes, and two villas were designed. One of each type was a simple and square compact design while the other was a more aesthetic shaped design. While reviewing the energy consumption calculations, the aesthetically designed duplex and the aesthetically designed townhouse proved to consume smaller amounts of energy than the remaining building designs. These two designs consumed smaller amounts of energy to heat the buildings and provided additional space for solar cells. The compact duplex design ended up being the only design to be able to achieve the Miljöbyggnad Gold certification, but the energy consumption of the building did not compete with the aforementioned designs. The exterior materials to be used were chosen because of their low ecological impact and how well they blend with the surroundings. The comparisons of three different types of buildings with two different designs of each helps highlight the many factors that affect the efficiency and sustainability of a building. After studying and comparing many real-world examples of energy efficient housing with these theoretical designs, the aesthetically designed duplex and townhouse will be the best performing floor plans for the eco-village in Glimåkra, Skåne. / Detta examensarbete har gått ut på att planera en ekoby i Skåne. En situationsplan innehållande radhus och parhus har tagits fram med diverse vägar, grönska och gemensamma byggnader. Arbetets övergripande syfte är att uppmärksamma ekobyar och dess miljövänliga ekohus. Det är beräkningar, modellering, extern och intern handledning samt diskussioner kring energi, miljöbyggnad och estetik som genomsyrat arbetet. För att nå ett resultat dras kopplingar från tidigare forskning och publiceringar med detta arbete. Litteraturstudien innehåller certifieringssystemet Miljöbyggnad, där betygskriterierna för Guld är det som arbetet har strävat mot för byggnaderna som modellerades. I Miljöbyggnad finns även nivåerna Brons och Silver, men om någon av indikatorerna ger nivå Brons är det inte möjligt att uppnå Guld som slutgiltig nivå. En av två studerade fasadmaterial valdes till byggnaderna i ekobyn och trä valdes på grund av dess fördelar och användningsgrad i området. Den uppvärmningskälla som studerades var pelletspanna och vid valet av elkälla genomfördes en kritisk granskning av solceller samt en mer grundläggande faktainsamling av direktverkande el. Genom platsbesök, ritningar och kartor samt diskussion och revidering modellerades två utformningar av parhus, radhus och villa. Det blev tre kompakta byggnader och tre mer estetiskt utformade och dessa modellerades i Autodesk Revit. Beräkningar genomfördes både manuellt och digitalt och hjälpmedel som formler, tabeller och antagna värden användes. Parhus Estetisk och Radhus Estetisk valdes ut för att placeras i ekobyn. Dessa valdes ut på grund av dess energiförbrukning, antal bostäder och dess estetik. Parhus Estetisk på 113m² och Radhus Estetisk på 114m² hade en total energianvändning per år på 10 500 kWh respektive 10 100 kWh, där ingår uppvärmning, tappvarmvatten och hushållsel. Det får plats 20 bostäder och 80 personer för den valda situationsplanen. Utifrån beräkning och simulering resulterade parhuset och radhuset i den slutgiltiga nivån Silver. Slutsatserna av detta arbete var att det var svårare än tänkt att uppfylla betygskriterierna för Guld i certifieringen Miljöbyggnad, endast Parhus Kompakt nådde nivån Guld. De valda byggnaderna i ekobyn var de bästa alternativen och en övergripande slutsats var att arbetet blev mer som ett förarbete som måste tas vid och utvecklas.

Som följd av EUs direktiv om nya byggnaders energiprestanda ökar kraven på det svenska byggnadsbeståndet. Passivhusstandard är ett energiklassningssystem som kan nyttjas som verktyg för att nå energieffektiva byggnader. Att nå denna standard i små byggnader innebär dock enligt tidigare studier en utmaning och i Sveriges norra halva finns få passivhus, särskilt sådana som uppförts av egnahemsbyggare. Det gör det svårt att bedöma vad standarden innebär för den private beställaren av små enbostadshus, utifrån tidigare erfarenheter av motsvarande projekt. Denna studie syftar till att öka förståelsen för utmaningar vid byggande av små enbostadshus med passivhusstandard i norra Sverige. Det övergripande målet är att ta fram rekommendationer till beställare i norr som står inför val av energiprestandanivå för sina små enbostadshus, utifrån insikter som genereras av ett studieprojekt. Vilken energiprestanda som är rimlig för enbostadsbyggnader < 70 m2 i norr, är en av de frågor som svar söks på. Bedömningen görs utifrån svensk klassning av passivhus från Forum för Energieffektivt byggande, FEBY 18. Vidare ställs frågan hur utmaningarna ser ut för projekt av motsvarande omfattning där passivhusstandard eftersträvas. För att besvara frågorna har ett skarpt projekt valts som studieprojekt och utgångspunkt. Studieprojektet innebär en komplementbyggnad i ett plan om 55 m2 Atemp som planeras av egnahemsbyggare i Skellefteå för totalentreprenad. I studien ingår litteraturgenomgång om passivhusteknik och dess tillämpning i projekt samt fallstudie om Studieprojektet innefattande gestaltningsförslag, anbudsförfrågan till entreprenörer och intervjuer med dem. För kompletterande insikter till det studerade området, små enbostadshus med strävan mot passivhusstandard i norra Sverige,har även samtal skett med personer med erfarenhet av liknande projekt och personer med expertkunskap om passivhusstandarden. En av utmaningarna som identifierats är de tekniska lösningar som krävs för att teoretiskt uppnå energiprestanda motsvarande passivhus, FEBY Guld. Dessa fordrar en investeringskostnad som inte bedöms vara rimlig för byggnader av så liten skala. I studiens resultat framgår att den lägre nivån FEBY Silver är en mer rimlig målsättning för enbostadsbyggnader < 70 m2 i norr men att även den nivån kan innebära en utmaning för beställare. Hängivenhet hos beställare till energieffektiviserande lösningar är centralt för möjligheten att nå FEBY Silver. När dessa tekniska lösningar efterfrågas från en totalentreprenör med begränsad erfarenhet av energieffektiva småhus kan det vara svårt att fånga entreprenörers intresse. Dessutom kräver entreprenadformen relativt mycket arbete av entreprenörer vid kostnadskalkylering. Här identifieras utmaningar som spåras till att entreprenören bär funktionsansvaret som totalentreprenör vilket leder det till slutsatsen att beställare bör välja utförandeentreprenad för enbostadshus under 70 m2 i norra Sverige, med strävan mot passivhusstandard. Förslag på vidare studier innefattar att jämföra förutsättningar för låg energianvändning i olika, små byggnadstyper. Ytterligare förslag är att genomföra en ny anbudsförfrågan för Studieprojektet med utgångspunkt i resultatet från denna studie, för djupare insikter i kostnadsrelaterade utmaningar. / Stricter requirements for energy performance in buildings in Sweden is a result of a directive from EU. Passive house-standard is an energy classification system which can be used as a tool to reach energy efficiency in buildings. However, achieving passive house standard for small buildings is a challenge according to previous studies. Further, passive houses are few in the northern parts of Sweden, especially those built byprivate homeowners. Therefore, it’s difficult to assess what the standard means to private buyers of small single-family homes, based on previous experiences. This study aims to increase the understanding of challenges when building small single-family homes of passive house-standard in the north of Sweden. The main goal is to make recommendations to buyers of small single-family homes in the north who are facing the decision of what energy performance level to target, based on insights generated by a study project. One of the questions asked is -What is an appropriate level of energy performance of single-family homes <70 m2 in the north? The assessment is based is based on the Swedish classification system for passive houses, FEBY 18. The second question asked is -What are the challenges facing projects of this scale, where the passive house standard is sought? To answer the questions, a real project has been chosen for study and reference point. The Study Project is a 55 m2 Atemp single-storey house which is planned by private home-owners for a turnkey contract, on a real estate with an existing residence in Skellefteå. The study includes a literature review on passive house technology and its application in projects, as well as a case study of the Study Project containing a design proposal, a request for turnkey proposals from selected contractors and further contact with these through interviews. People with experience of relevant projects and people with expert knowledge of passive house standard have been contacted to reach additional insights within the studied area. Among the identified challenges are the building solutions and techniques which are required to reach passive house-standard, “FEBY Gold”. These solutions entail an investment cost that’s not considered to be reasonable for buildings of such a small scale. The study’s result shows that the lower energy level “FEBY Silver” is an attainable objective but still, this level as target can pose a challenge to the buyer.  A buyer’s dedication to energy efficient solutions is central for the prospect of having the Silver level within reach. When these building solutions are requested from a turnkey contractor with limited experience of energy-efficient, small houses, obstacles arise in making the project attractive for contractors as relatively much work is required when calculating costs. Here, challenges are identified that relates to the contractor being responsible for the function of the finished product, the house. This leads to the conclusion that private buyers should opt for other contract types than turnkey, for single-family homes < 70 m2in northern Sweden, when aiming for passive house standard.  Suggestions for further studies includes comparing the conditions for low energy use in different, small building types. Another suggestion is to carry out a new request for proposal of the Study Project and make adaptions according to the insights given by this study and thus, investigate the cost-related challenges further.

Aujourd'hui, la maîtrise de l'énergie est la question prépondérante pour la croissance économique des entreprises industrielles. En effet, l’énergie est une ressource qui se raréfie et qui devient de plus en plus coûteuse. L’optimisation énergétique est donc un défi majeur que doit relever les entreprises et principalement celles manufacturières pour supporter les exigences du développement durable. Cette optimisation est à construire prioritairement par une amélioration de l’efficacité énergétique (EE), c'est-à-dire réduire la quantité d'énergie requise pour produire des produits et des services. En regard de ce défi énergétique, l’objectif de cette thèse est d’investiguer la considération de l’efficacité énergétique et de sa prévision comme un nouvel indicateur pertinent dans la prise de décision en maintenance. En ce sens, nous proposons tout d'abord un concept de l’efficacité énergétique, appelé EEI (EE indicator), applicable aux différents niveaux d’abstraction d’un système industriel. Nous définissons ensuite une formulation générique permettant d’évaluer l'EEI (et son évolution) en prenant en compte les facteurs d’influence statiques et dynamiques. Cela nous amène à fonder un concept de performance d’efficacité énergétique, appelé REEL (Remaining Energy-Efficient Lifetime), représentant la durée de vie énergétique résiduelle. Pour prédire l’évolution potentielle de l’EEI qui permettra de calculer la REEL, une approche générique basée sur des approches de pronostics existantes est également développée. Ensuite, nous investiguons l'utilisation d’EE dans la prise de décision en maintenance conditionnelle (Condition-Based Maintenance, CBM). Enfin, toutes ces contributions sont validées sur la plateforme laboratoire TELMA / Among sustainability consideration, energy is today the key for economic growth in industrial systems. Energy resources are however limited and becomes more and more expensive. The energy optimization of manufacturing systems must therefore be considered as a major challenge to be compliant with environmental impact and management of energy resources. This should be reflected primarily by using energy efficiency (EE) as main key lever to deploy sustainability to plants, i.e. reduce the amount of energy required to provide products and services. With regards to this EE context, the aim of this thesis is to investigate the problem of considering energy efficiency and its prediction as a new indicator in maintenance decision-making. In that way, we develop first a concept of energy efficiency, called EEI (energy efficiency indicator), applicable to the different levels of abstraction of an industrial system. Then, we propose a generic formulation to evaluate the EEI (and its evolution) taking into account static and dynamic factors of influence. The temporal evolution of this indicator with respect to the degradation of the system is addressed in a predictive maintenance objective. It leads to found an energy efficiency performance concept called REEL (remaining energy-efficient lifetime), representing the residual energy lifetime. To predict the potential evolution of the IEE to calculate REEL, a generic approach based on existing predictive approaches is also developed. Next, we investigate the use of EE in CBM maintenance decision-making. Finally, all these contributions are validated on the TELMA platform