High-pressure fog (HPF) systems have advantages for greenhouse cooling compared to traditional systems, such as pad and fan. Such advantages include the potential of improving climate uniformity. Water is distributed throughout the greenhouse space thus reducing water use and energy operation costs, especially if used within naturally ventilated greenhouses. Fog cooling in combination with natural ventilation is difficult to manage, primarily because accurate estimation of air exchange rates is required to determine the precise amount of fog required. This limitation on automated control has been the main reason restricting the widespread commercial use of HPF systems. The goal of this research was to develop and implement a control strategy for a naturally ventilated greenhouse with a variable HPF system. The strategy that was developed included variable rate of fog introduced into the greenhouse, a dynamic control of the air ventilation openings, and it considered the contribution of cooling and humidification from the crop by evapotranspiration. Three evapotranspiration models, including Penman-Monteith, Stanghellini and Takakura, were calibrated and evaluated in terms of prediction accuracy. The Stanghellini model provided the best overall performance for several growing seasons and under two different evaporative cooling systems (i.e. pad and fan and natural ventilation with HPF), and was selected and implemented in the cooling control strategy. The strategy utilized enthalpy and vapor pressure deficit (VPD) of the greenhouse atmosphere for the control parameters. Using a calibrated greenhouse mechanistic climate model, a computer algorithm was created to simulate the capabilities of the proposed. The control strategy that was developed was able to maintain the greenhouse climate closer to the pre-established set points while consuming less water and energy, compared to a constant HPF system based on VPD control. Finally, the strategy was implemented in a single span research greenhouse. A four-day validation study provided good agreement for measured and simulated greenhouse climate values, as well as for water and energy use. Moreover, the strategy was able to maintain VPD around its set point for all the experiments and temperature remained around its set point when outside enthalpy was lower than the enthalpy set point.

A b s tra c t The recent discussion of the European Parliam ent, member states, and citizens triggered the question whether there is s till a need for bi-annual clock shifting from the perspective of energy savings. Employing the difference-in-differences method on hourly data on electricity consumption between 2006 and 2017, the study con­ cludes th a t daylight saving tim e policy reduces aggregate electricity consumption by 0.35 % in the Czech Republic. Moreover, daylight saving tim e leads to 1% savings on domestic residential electricity consumption. Overall, daylight saving tim e increases electricity consumption in the morning, bu t decreases electricity consumption in the evening by greater amount. We have estimated th a t more than 65 % of to ta l electricity savings attributable to daylight saving tim e arose from effect of the daylight saving tim e on residential electricity consumption. 1

The façade retrofit market faces some key barriers: the selection of performance criteria and the reliability of the performance data. On the demand side, the problem is approached from an investment perspective which creates "split incentives" between the stakeholders who pay for the investment and those who benefit from it. On the supply side, there is an inherent complexity in modeling these options because of the incomplete knowledge of the physical and cost parameters involved in the performance evaluation. The thermal comfort of the building occupant is an important component of the retrofit performance assessment. This research attempts to fill a gap in the approach to façade retrofit decision by 1) quantifying uncertainties in these three dimensions of performance, 2) incorporating new financing models available in the retrofit market, 3) considering the target and risk attitude of the decision maker. The methodology proposed in this research integrates key indicators for delivery process, environmental performance, and investment performance. The purpose is to provide a methodological framework for performance evaluation. A residential case study is conducted to test the proposed framework. Three retrofit scenarios including the financing structure are examined. Each façade retrofit scenario is then evaluated based on the level of confidence to meet or exceed a specific target improvement for the Net Present Value and the risk to fall below a minimum improvement threshold. The case study results confirm that risk must be considered for more reliable façade retrofit decision-making. Research findings point to further research needed to expand the understanding of the interdependencies among uncertain parameters.

La consommation énergétique des centres de calculs et de données, aussi appelés « data centers », représentait 2% de la consommation mondiale d'électricité en 2012. Leur nombre est en augmentation et suit l'évolution croissante des objets connectés, services, applications, et des données collectées. Ces infrastructures, très consommatrices en énergie, sont souvent sur-dimensionnées et les serveurs en permanence allumés. Quand la charge de travail est faible, l'électricité consommée par les serveurs inutilisés est gaspillée, et un serveur inactif peut consommer jusqu'à la moitié de sa consommation maximale. Cette thèse s'attaque à ce problème en concevant un data center ayant une consommation énergétique proportionnelle à sa charge. Nous proposons un data center hétérogène, nommé BML pour « Big, Medium, Little », composé de plusieurs types de machines : des processeurs très basse consommation et des serveurs classiques. L'idée est de profiter de leurs différentes caractéristiques de performance, consommation, et réactivité d'allumage, pour adapter dynamiquement la composition de l'infrastructure aux évolutions de charge. Nous décrivons une méthode générique pour calculer les combinaisons de machines les plus énergétiquement efficaces à partir de données de profilage de performance et d'énergie acquis expérimentalement considérant une application cible, ayant une charge variable au cours du temps, dans notre cas un serveur web.Nous avons développé deux algorithmes prenant des décisions de reconfiguration de l'infrastructure et de placement des instances de l'application en fonction de la charge future. Les différentes temporalités des actions de reconfiguration ainsi que leur coûts énergétiques sont pris en compte dans le processus de décision. Nous montrons par simulations que nous atteignons une consommation proportionnelle à la charge, et faisons d'importantes économies d'énergie par rapport aux gestions classiques des data centers. / The increasing number of data centers raises serious concerns regarding their energy consumption. These infrastructures are often over-provisioned and contain servers that are not fully utilized. The problem is that inactive servers can consume as high as 50% of their peak power consumption.This thesis proposes a novel approach for building data centers so that their energy consumption is proportional to the actual load. We propose an original infrastructure named BML for "Big, Medium, Little", composed of heterogeneous computing resources : from low power processors to classical servers. The idea is to take advantage of their different characteristics in terms of energy consumption, performance, and switch on reactivity to adjust the composition of the infrastructure according to the load evolutions. We define a generic methodology to compute the most energy proportional combinations of machines based on hardware profiling data.We focus on web applications whose load varies over time and design a scheduler that dynamically reconfigures the infrastructure, with application migrations and machines switch on and off, to minimize the infrastructure energy consumption according to the current application requirements.We have developed two different dynamic provisioning algorithms which take into account the time and energy overheads of the different reconfiguration actions in the decision process. We demonstrate through simulations based on experimentally acquired hardware profiles that we achieve important energy savings compared to classical data center infrastructures and management.

This master thesis determines and compares operating costs (energy balance) of family houses, depending on their age and during their life cycle. The basic terms, heat-technical properties and technological procedures of improving heat-technical properties are defined in the first part of the thesis. In the practical part, the operating costs of three older houses are determined. Variants of building modifications to improve heat-technical properties are suggested and evaluated. Certificates of energy performance were determined and the values compared, for both the current state of the houses and for the state after the improvement heat-technical properties. The thesis includes calculation of building modifications costs and the payback period of the investment.

This thesis examines the influence of insulation of perimeter structures on the price of residential units in model house. Model example is prefabricated house in the town of Vyškov. The aim is to determine whether is the investment for owners of individual apartments beneficial and, if so, what is its return time. Two views on this issue are saving energy for heating and appreciation of prices of apartments. The secondary objective is considering other options to save energy.

The aim of this diploma thesis is assessment of options to reduce energy consumption in industrial areal belonging to Fritzmeier company. This thesis is divided into three parts. In the first part there is analysis of electrical energy and natural gas consumption in considered industrial area based on data from energy audit. The second part consists of short theoretical elaboration of cogeneration and cogeneration technologies, design of five variants of use of cogeneration units with combustion engine running on natural gas and evaluation of proposed variants. Third part of this thesis is about modernization of lighting system in small section of assembly hall. In this part parameters of new LED lighting system for selection are set, based on theoretical elaboration of LED problematics and five variants offered by specialized companies are evaluated.

As buildings have become more energy efficient, the energy demand for preparation of domestic hot water stands out as an increasing part of the operational cost and carbon footprint of a building. Most of the heat in the water is used for a short time and then discharged to the main sewer line. Clarion Hotel Stockholm is an example of such a building, with many showers, bathtubs and a spa. The hotel business is growing around the world and its customers demand comfortable stays. A parallel trend is a more environmentally aware tourism and business travel. Hotels show a great potential for energy savings, while still offering comfortable accommodation. In this master's thesis a case study evaluates the possibilities for heat recovery from the wastewater of Clarion Hotel Stockholm. Three types of heat exchangers were modelled in the system dynamic modelling environment STELLA: a horizontal, a vertical and a shower heat exchanger. Recovered heat was used for pre-heating of the incoming water for domestic hot water preparation. The flows of heat through the hotel's tap water and wastewater systems were schematically modelled using system dynamic modelling, which provides a foundation for the development of mathematical models and further research into the area. The first results point to possible reductions of the heating demand for domestic hot water preparation at Clarion Hotel Stockholm.

The thesis concentrates on residential buildings evaluation from energy and financial savings perspective. More than 40 % of the total man-induced energy consumption is directed to building construction and maintenance. In these buildings, we spend majority of our lives. The aim of the study is thus to support the discussion about the benefits from new, both energetically and environmentally considerate building trends. Theoretical part of the thesis is devoted to ecologically efficient family houses and their distinctive features in comparison to commonly built houses, whereas empirical part compares these building types from the energetic and financial viewpoint. Thesis goes on with most frequent ,myths' about sustainable architecture. As a conclusion, the study aims to point out which building type is the most advantageous in terms of energy, finance, sustainability etc. Keywords: Sustainable architecture, Passive house, Energy savings, Sustainable development

Several studies have shown that the buildings envelope optical properties are important in terms of energy use and thermal comfort level. However, no study has been found in regard of the optimal optical properties for the building envelope. Moreover, developments in the coil-coating industry have made possible to design cost effective optical selective surfaces for the construction sector. Based on the above mentioned, this study pretends to map the envelope optimal optical properties minimizing the energy use for large-open-volume buildings locates in Stockholm, Copenhagen, Liverpool, Amsterdam, Berlin, Vienna, Bern, Rome, and Madrid.A building could be seen as a very complex solar energy conversion system, which is very difficult to describe accurately. Nonetheless, it is possible to use Building Energy Simulation (BES) tools to model, to some extent, its thermal performance under many simplistic assumptions. The simulation tool TRNSYS 17 and the optimization tool GenOpt were selected for this study. Additionally, detailed small-open-volume building thermal performance data, obtained during passive measurements from the steel manufacturer SSAB, in Borlänge-Sweden, were used to assess the methodology for the creation of the large-open-volume simulation models. The variations in large-open-volume building design around Europe are not well documented, which constitutes one of the major impediments for this research. However, detailed European historical building U-value data from the European Union project called iNSPiRe made it possible to achieve the objective of this study.The simulation work showed, that the building envelope optimal optical properties are related to the magnitude of the heating and cooling loads. Consequently, GenOpt was used to plot the sensitivity of the building envelope optimal optical properties to the ratio between the heating demand and the total energy demand (Qheat/Qtotal). In regard to the large-open-volume building optimal optical properties in the selected locations, it was found that the allocation of optimal optical properties does not lead to significant energy savings in locations with relatively low solar availability and high thermal insulation levels. Nonetheless, a final envelope optical properties study for a small-open-volume building model based on three existing buildings differing only on their optical properties was made for 243 world-capital cities. The simulations reinforced the results for the large-open-volume building in the European locations, and additionally showed huge energy savings potential for most of the world capital cities. This investigation restates the results obtained by Joudi (2015), “Possible energy savings by the smart choice of optical properties on the interior and exterior surfaces of the building.” / Varios estudios han demostrado que las propiedades ópticas de las envolturas delos edificios son importantes en términos de consumo energético y de nivel deconfort térmico. Sin embargo, no se ha encontrado estudio alguno con respecto alas propiedades ópticas óptimas para las envolturas de los edificios.Conjuntamente, los desarrollos en la industria de bobinas metálicas revestidas hanhecho posible diseñar superficies selectivas rentables para el sector de laconstrucción. Basándose en lo anteriormente expuesto, este estudio pretendemapear las propiedades ópticas óptimas de la envoltura que minimizan el uso deenergía para edificios de gran volumen abierto localizados en Estocolmo,Copenhague, Liverpool, Ámsterdam, Berlín, Viena, Berna, Roma y Madrid.Un edificio podría ser visto como un sistema de conversión de energía solar muycomplejo, que es muy difícil de describir con precisión. No obstante, es posibleutilizar las herramientas de Simulación de Energía de Edificios (BES) para modelar,hasta cierto punto, su rendimiento térmico bajo una considerable cantidad desuposiciones simplistas. El programa de simulación TRNSYS 17 y el programa deoptimización GenOpt fueron seleccionadas para este estudio. Adicionalmente, conel fin de evaluar la metodología utilizada para la creación de los modelos desimulación para edificios de gran volumen abierto, se utilizaron datos detallados derendimiento térmico de edificios de pequeño volumen abierto, obtenidos durantemediciones pasivas del fabricante de acero SSAB, en Borlänge-Suecia. Lasvariaciones en el diseño de edificios de gran volumen abierto en toda Europa noestán bien documentadas, lo que constituye uno de los principales impedimentospara esta investigación. Sin embargo, los datos detallados y en orden cronológicode los niveles de aislamiento térmico (U-value) en la construcción europea,recopilados por el proyecto de la Unión Europea llamado iNSPiRe, permitieronalcanzar el objetivo de este estudio.El trabajo de simulación demostró que las propiedades ópticas óptimas de laenvoltura del edificio están relacionadas con la magnitud de las cargas decalefacción y refrigeración. En consecuencia, GenOpt fue utilizado para graficar lasensibilidad de las propiedades ópticas óptimas de la envolvente del edificio conrespecto a la proporción entre la demanda de calefacción y la demanda total deenergía (Qheat/Qtotal). En cuanto a las propiedades ópticas óptimas del edificio degran volumen abierto en las ubicaciones seleccionadas, se encontró que laasignación de propiedades ópticas óptimas no conduce a ahorros de energíasignificativos en ubicaciones con disponibilidad solar relativamente baja y altosniveles de aislamiento térmico. Sin embargo, un último estudio de propiedadesópticas de envolvente para un modelo de construcción de pequeño volumen abiertobasado en tres edificios existentes que difieren sólo en sus propiedades ópticas serealizó para 243 capitales mundiales. Las simulaciones reforzaron los resultadospara el edificio de gran volumen abierto en las localidades europeas, y ademásmostraron un enorme potencial de ahorro de energía para la mayoría de lascapitales mundiales. Esta investigación reitera los resultados obtenidos por Joudi (2015), "Posibles ahorros de energía por la elección inteligente de propiedadesópticas en las superficies interiores y exteriores del edificio".