In recent years, HVAC systems of commercial buildings imposed heavy load on power demand, especially during summertime on-peak periods. The HVAC power consumption of commercial buildings usually accounts for 40% of total which indicated huge potential for energy-savings if proper operation strategies can be implemented. In this research, three different operational strategies were studied in an attempt to conserve energy, namely: the Night Purge, Free Cooling,and Pre-cooling. They were simulated , under the local weather conditions, and then validated with full-scale experiments.The experimental results indicated that significant load-shifting effect can be experienced, which also warranted good engineering application potentials when coupled with other HVAC energy-savings operation strategies.

De nos, jours avec la démocratisation des équipements électroniques et l’explosions des services informatiques proposés sur le web, la consommation des datacenters devient un enjeu énergétique et économique majeur. Ce terme qui peut être traduit par « centre de calcul », désigne les infrastructures qui hébergent et font fonctionner en permanence des serveurs informatiques. Son rôle est de fournir aux équipements électroniques un environnement thermique adapté, ainsi qu’une alimentation électrique stable de manière à assurer une très grande sécurité de fonctionnement. Mais l’activité permanente des serveurs génère de grandes quantités de chaleurs, et un refroidissement permanent est nécessaire. Cette étude à pour objectif de mieux comprendre les phénomènes physiques qui interviennent dans le fonctionnement des datacenters afin d’apporter des solutions pour optimiser leur fonctionnement et diminuer leur consommation. A l’aide de simulations numériques, nous étudions les écoulements d’air et les transferts de chaleur qui interviennent dans la salle informatique, et nous proposons un nouveau modèle numérique qui permet de simuler le comportement des serveurs de nouvelle génération. Puis, grâce à une méthode de type POD, couplée au logiciel TRNSYS, nous développons un modèle « transversal » capable de simuler le fonctionnement complet d’un centre de calcul depuis les équipements informatiques, jusqu’au système de production d’air froid. Finalement, ce dernier est employé pour concevoir et tester un système de régulation adaptatif qui permet de réduire significativement les consommations d’énergie. / Nowadays, with the constant evolution of Information Technology (IT) equipments, the energy consumption of datacenter over the world becomes a major concern. These infrastructures are designed to provide an adapted thermal environment and an uninterrupted power supply to the IT servers, in order to guarantee a high level of reliability. However, the constant activity of electronic equipments releases a large amount of heat, and requires a constant cooling. Thus the objective of this work is to study the physical phenomena involved in an operating datacenter, in order to optimize the process and to reduce its energy consumption. Using numerical simulation, we study the air flow and the heat transfers happening in the servers’ room. To quantify the impact of new generation servers on the cooling process, we propose a numerical model that simulates the behavior of “blade” server. Then, using a Proper Orthogonal Decomposition (POD) method linked to the software TRNSYS, we propose a new “transversal” model, that simulates a datacenter behavior from the servers to the cooling plant. This model is used to develop a new adaptive regulation strategy, which constantly optimizes the system in order to ensure a safe thermal environment, and provides large energy savings.

Lågtempererade värmekällor som ytvatten och borrhålslager kan i samverkan med en värmepump ses som outnyttjade energikällor. En sjö- och borrhålsbaserad anläggning kan ha en hög total effektivitet om både värme och kylbehov finns och en stor fördel är att frikyla kan användas från sjö och borrhål under delar av året. Kungsbrohuset byggdes 2008 - 2010 med målsättningen att bli världens mest energieffektiva kontorsbyggnad. Mer specifikt var målsättningen att köpt energi skulle vara hälften av boverkets regler. Av den totala bruksarean på 27 000 m2 utgörs ca 19 500 m2 av kontorsyta. Anläggningen värms och kyls huvudsakligen av en värmepump med en värmeeffekt på 350 kW. Vintertid används värmepumpen för både värme och kyla då ett stort kylbehov även finns under uppvärmningssäsongen till serverrum mm. När värmepumpen inte räcker till så används fjärrvärme och fjärrkyla/sjökyla för att täcka behovet. Vid byggnationen installerades en ledning mellan kungsbrohuset och centralstationen för att på centralstationen utnyttja frikyla från sjön samtidigt som kungsbrohuset fick möjligheten att utnyttja värmen i köldbärarreturen. Målet med studien var att utvärdera anläggningen med fokus på tre huvudsakliga frågor. Att undersöka om värmepumpen har högsta möjliga temperatur på förångningssidan vintertid var den första. Den andra frågan var om frikyla från sjön utnyttjades optimalt. Den tredje frågan var att jämföra den projekterade energianvändningen med det verkliga utfallet. Studien utfördes genom besiktningar på plats, insamling av energistatistik samt att studera anläggningen genom driftdator, driftkort, flödesscheman etc. Vintertid så har den egna köldbärarreturen använts nästan uteslutande som värmekälla till värmepumpen då dess temperatur är högre än borrhålslagrets. Utnyttjandet av frikyla från sjön har inte fungerat optimalt då fjärrkyla har använts under vintermånaderna trots att sjöns temperatur är låg. Detta kan åtgärdas genom omprogrammering av villkor för aktivering av frikylan. Jämförelsen mellan projekterad köpt fastighetsenergi på 47 kWh/m2, år med det verkliga utfallet visade att användningen är något högre i verkligheten och hamnade på 55 kWh/m2, år efter att processkylan räknats bort då den inte räknas som fastighetsenergi. Anläggningen är totalt sett väldigt effektiv och har en mycket låg användning av köpt energi. Att kylbehov finns även vintertid gör att värmepumpens effektivitet blir maximal då nyttig energi utnyttjas på båda sidorna.

The backbone of the expanding Information and Communication Technology (ICT)-sector are data centers. In these, Information Technology (IT) equipment is housed which provides computational power for e.g. cloud computing and internet services. Data centers consume massive amount of electricity, estimated to 1% of the global demand. All this power is however not used directly by the IT equipment, to keep the operating conditions in the desired range 21-61% of the electricity is used by the cooling solution. This is mainly due to the extensive use of vapor-compression refrigeration systems (VCRS) which provide a dependable cooling solution that works independent of climate conditions. To get around VCRS the concept of free cooling has been utilized in data centers, this can be done in many ways but the main idea is to introduce a natural cooling source without compromising the operating environment. Previous studies have showed that direct airside economization, i.e. using outdoor air directly in the data center have potential to reduce the energy demand of the cooling solution. This is however directly dependent on the outdoor conditions, by combining direct airside economization with direct evaporative cooling and recirculation of hot air from the IT equipment the cooling solution can handle a wider range of weather conditions and still keep the operating environment in desired conditions. Simulations of similar cooling solutions have been been done by Endo et al. and Ham et al. and showed promising results, but no study of an experimental setup have been published. To test how direct airside economization with direct evaporative cooling technology performs and find its characteristics an experimental setup was constructed, coolers with direct airside economziation and direct evaporative cooling was installed in a data center module at RISE SICS North data center ICE. The setup consisted of 12 racks of OCP Winterfell servers in a hot and cold aisle setup with containment, ducts on the ceiling connected the hot aisle to the coolers and made recirculation of hot air possible. A test schedule was developed to test the cooling solution in two of its four operating modes where the IT-load and setpoint temperatures where adjusted in predefined steps. The IT equipment consumed between 60 - 100kW and the facility power varied between 1.5 - 7kW, which results in a power usage effectiveness (PUE) value between 1.02 and 1.08. Compared to traditional VCRS systems these are very low values. By running the coolers in evaporative cooling mode the PUE was consistently lower compared to ventilation mode, the supply air temperature drop was up to 10°C while in cooling mode. The water consumption, and the corresponding water usage effectiveness (WUE) value was not measured or calculated due to limitations of the test rig that made long tests unstable. Direct airside economization with direct evaporative cooling is not the cooling solution for all data centers in all climates. But if the right conditions are present it is a simple cooling solution that without VCRS or heat exchangers (HEX) shows impressive PUE capabilities. Due to the psychical limitations of the system it can not handle high temperature and/or humidity levels, the data center either needs to be shut down, operated in undesirable conditions or complemented with a separate cooling system to operate in these conditions. To find the limits for this system supply air alteration and removal of exhaust air needs to be implemented. Due to the natural limitations of evaporative cooling combined with the ASHRAE guidelines the technology needs to be further researched to find what climate conditions it can handle. The water consumption which according to previous studies can be substantial also needs to be further studied.

Data centers requires a lot of energy due to that data centers count as the buildings also contains servers, cooling equipment, IT-equipment and power equipment. As the cooling solution for many data centers around the world right now, the compressor-based cooling solution counts for around 40% of the total energy consumption. A non-compressor-based solution that is used in some data centers, but also is in a research phase is the free cooling application. Free cooling means that the outside air is utilized to cool down the data center and there are two main technologies that contains within free cooling: airside free cooling and waterside free cooling. The purpose of this master thesis is to analyze two types of coils; one corrugated and the other one smooth, providing from Bensby Rostfria, to investigate if it is possible to use free cooling in 5G EDGE data center in Luleå, with one of these coils. The investigation will be done during the warmest day in summer. This because, according to weather data, Luleå is one candidate where this type of cooling system could be of use. The project was done through RISE ICE Datacenter where two identical systems was built next to each other with two corrugated hoses of different diameter and two smooth tubes with different diameter. The variables that was measured was the ambient temperature within the data hall, the water temperature in both water tanks, the temperature out from the system, the temperature in to the system and the mass flow of the air that was going to go through the system. The first thing that was done was to do fan curves to easier choose which input voltages for the fans that was of interest to do further analysis on. After that was done, three point was taken where the fan curve was of most increase. The tests were done by letting the corrugated hoses and smooth tubes to be in each of the water tanks and fill it with cold water. It was thereafter the coils that should warm the water from 4,75 °C – 9,75 °C, because of that the temperature in the data center was around 15 °C. The rising in particularly these temperatures was chosen because it is seen that to use free cooling the temperature differences must be at least 5 °C. The tests were done three times to get a more reliable result. All the data was further taken in to Zabbix and to further analysis in Grafana. When one test was done the files was saved from Grafana to Excel for compilation, and thereafter to Matlab for further analysis. The first thing that was analyzed was if the three different tests with the same input voltages gave similar results in the water temperature in the tank and the temperature out from the system. Thereafter, trendlines was built to investigate the temperature differences in and out of the system, the temperature differences in and the water temperature in the tank, the mass flow and the cooling power. That trendline was further in comparison to each other, which was 2D-plots between the cooling power and the temperature differences between the inlet and the water. Thereafter the both coils could compare to each other to see which of them that gave the largest cooling power and was most efficient to install in a future 5G data center module.  The conclusion for this master thesis is that the corrugated hose will give a higher cooling power with higher temperature differences outside, but during the warmest summer day it was distinctly the smooth tube that gave the largest cooling power and therefore the best result. The smooth tube also got, through hand calculations, the larger amount of pipe that was necessary to cool down the 5G module, but the smallest water tank. It was also shown that for the warmest summer day, a temperature in the water tank of 24 °C is the best, compared to 20 °C and 18 °C. The amount of coil that is needed to cool down the data center with a temperature in the water tank at 24 °C and how large the water tank differs between the two types of coils. For the corrugated hose a length of 1.8 km and a water tank of 9.4 m3. As for the smooth tube a length of 1.7 km and a water tank volume of 12 m3.  As can be seen throughout this project is that this type of cooling equipment is not the most efficient for the warmest summer day but could easily be used for other seasons.

Ground source cooling is commonly used for cooling of electronics in protected sites. Sometimes the boreholes are combined with free cooling from the air using a dry cooler to reduce the amount and length of the boreholes, which is the biggest part of the costs. The dry cooler can have two different running modes. In unloading mode the dry cooler is started at a certain temperature and the fans are slowed down at low temperatures so that the cooling power never exceeds the cooling demand. The extracted cooling is used to unload the boreholes. In recharging mode the dry cooler is started at a certain temperature and is operating at full capacity below this temperature. The excess cooling that is extracted in this mode is used to recharge the boreholes. The numerical simulation tool COMSOL Multiphysics was used to evaluate the borehole performance. The software can simulate tilted boreholes with good accuracy and makes it possible to adjust the geometry in any desired way. In this thesis, the performance of a 100 kW ground source cooling system is evaluated for a number of cases both with and without dry coolers in different running modes and sizes. The best solution in respect to life cycle cost, technical feasibility and environmental impact is chosen to be an unloading case with a dry cooler with 100 kW capacity at 8 °C. Using only boreholes gives less carbon dioxide emissions but much higher costs.

The residential building sector plays an important role in combating climate change in Canada. Many energy efficiency solutions along with new building energy standards have been implemented to improve building energy performance. However, their effects on energy saving and GHG emissions reduction vary due to the complexity of the building systems and the variability of their operational conditions. This work quantifies such variability in both energy efficiency devices and building energy standards implementation, respectively. The first study in this dissertation assesses the energy savings from sensible heat recovery in a residential apartment suite in various locations across Canada. A series of detailed building energy performance models are developed in TRNSYS. The HVAC system’s annual energy consumption is simulated and the results are compared with and without HRV for each climate zone. The results show the heating energy savings of employing the HRV vary from 17 to 34% depending on the winter climatic conditions; while, the building cooling energy use can be increased due to the undesired thermal recovery occurring in the HRV during the cooling season. The second study investigates the free cooling potential of outside air in various Canadian cities. A series of thermal models developed using BEopt 2.8 for a hypothetical single-family house with various window-to-wall ratios and building aspect ratios simulates hourly building cooling load profiles. The free cooling potential is analyzed by comparing the maximum available and the actual usable free cooling for various building features and different climates. The results indicate that, although free cooling is widely available in most areas of Canada during the summer and shoulder seasons, only 17-42% of such free cooling is usable without the use of thermal storage. The last study examines the effects of two building energy standards - the BC Step Code and the Passive House criteria - on reductions in residential household space heating GHG emissions under different enforcement scenarios. The space heating energy and the GHG emissions are estimated using the forecast growth of single detached households for the period from 2020 to 2032. The results show that the space heating GHG emissions can be reduced by 77% and 89%, respectively if the BC Step Code or the Passive House criteria is implemented in Canada. It is also found the impacts of energy code on GHG emission mitigation are less significant in regions where the carbon intensity of the dominant heating fuels is low. / Graduate

Un centre de données est un site comportant des salles hébergeant un grand nombre d’équipements informatiques. Le fonctionnement de ces équipements informatiques induit des apports de chaleur très conséquents qui doivent être compensés par des systèmes de refroidissement. En effet, les normes imposent des plages restreintes de température et d’humidité dans les salles qui induisent de fortes consommations d’énergie. Il est donc nécessaire de développer et d’optimiser des solutions moins énergivores. Le refroidissement par free cooling consiste à refroidir les équipements en exploitant les conditions climatiques favorables. Les travaux réalisés durant cette thèse s’appuient sur une expérimentation menée dans des conditions climatiques réelles au sein d’un bâtiment. Il s’agit d’étudier le refroidissement de baies informatiques. Pour mettre en place un refroidissement par « free cooling » indirect, la configuration du bâtiment a été modifiée au cours de la thèse et une instrumentation conséquente mise en place. Les objectifs sont de déterminer à partir de séquences de mesures des coefficients de performance, de développer et de valider un modèle numérique destiné à la prédiction du comportement thermo-aéraulique en usage de ce type de solution. Dans un premier temps, des expériences sont menées avec une puissance dissipée à l’intérieur du bâtiment et un refroidissement assuré uniquement par une circulation de l’air extérieur au sein de trois parois. Des modifications ont ensuite été apportées au sein du bâtiment. Une circulation d’air en circuit fermé a été créée à l’intérieure afin de refroidir les baies par un flux d’air traversant. Afin de disposer d’une base de données probante, de nombreuses séquences de mesures avec une ou plusieurs baies sont réalisées dans différentes conditions. La variation des paramètres opératoires permet de bien appréhender le fonctionnement de l’installation et définir les paramètres d’optimisation énergétique. Les modèles numériques sont développés par le biais de TRNSYS / TRNFLOW. La confrontation des simulations à des mesures montre la pertinence de la démarche mise en œuvre. / A data center is a warehouse that contains telecommunication equipment, network infrastructure, servers, and computers. This equipment leads to a very high heat dissipation which must be compensated by the use of cooling systems. Telecommunication standards impose restricted climatic ranges (temperatures and humidity) leading to a very high energy consumption devote to air conditioning. The reduction of this energy consumption constitutes a real challenge which should be raised and solved. Many cooling solutions are proposed as the free cooling solution, which consists in cooling equipment by using external air in propitious climatic conditions. The work carried out during this thesis is based on experiments conducted within a building in real climatic conditions in order to study the cooling of telecom cabinets. During this study, the building configuration was modified, an indirect "free cooling" system was set up and a significant instrumentation was implemented. The objectives are to establish performance factors issued from measurements, to develop and to validate a numerical model in order to predict the thermoaeraulic behavior for this type of solution. Initially, experiments are carried out with a power dissipated inside the building and a cooling provided only by an outside air circulation. Then, significant modifications were made into the building to introduce an internal air circulation in a closed loop in order to evacuate the heat dissipated inside cabinets by a crossing airflow. In order to get a convincing database, measurements were conducted by using one and then several cabinets in different conditions. Modifications are made to operating parameters in order to better understand the installation operation and to define the energy optimization parameters. Numerical models are developed through TRNSYS / TRNFLOW. The confrontation of simulations with measurements shows the implemented approach relevance.

För att hålla ett behagligt inomhusklimat på fartyg krävs kylning under den varma tiden på året. Denna kylning kräver energi. Detta arbete är en undersökning om huruvida denna energiåtgång kan minskas genom så kallad frikylning. ROPAX-färjan Finntrader som trafikerar linjen Malmö–Travemünde har använts som exempel. Undersökningen utfördes genom att skapa en beräkningsmodell där ett köldbärarsystem med möjlighet till frikylning kopplades in i Finntraders nuvarande HVAC-system, tillsammans med nuvarande kylmaskiner. Statistik över lufttemperatur, luftfuktighet och sjövattentemperatur för perioden 2013–2015 införskaffades. Denna statistik fördes in i beräkningsmodellen. Resultatet av beräkningarna blev att en viss mängd energi kunde sparas med frikylning, hur mycket beroende på värmeväxlarnas effektivitet. Mängden energi som kunde sparas var förhållandevis liten jämfört med kostnaden för de komponenter modellen krävde. / To maintain a comfortable climate on board ships, cooling is necessary during the warm period of the year which requires energy. This thesis is a survey about whether so-called free cooling could reduce this energy consumption. The ROPAX-ferry Finntrader trafficking the route Malmö–Travemünde has been used as an example. This survey was carried out by creating a calculation model in which a brine system with a possibility of free cooling was connected to Finntrader’s current HVAC-system, alongside the current chillers. Statistics of air temperature, air humidity and sea water temperature was acquired for the period 2013-2015 and were inserted into the calculation model. These calculations showed that a certain amount ofenergy could be saved with free cooling, how much depending on the effectiveness of the heat exchangers. The amount of energy that could be saved was quite small compared to the cost of the components required by the model.

The diploma thesis deals with possibilities and subsequent proposal of individual measures to achieve the reduction of energy intensity in the company fischer Vyškov, s.r.o. At the beginning of the thesis is the analysis of the current state of the areas on which the work is further focused. These include the production of compressed air, cooling technology and lighting. The main cost-saving measures for the production of compressed air is a proposal to purchase a new compressor. For cooling, there are free cooling options, including the design of a dry cooler and its inclusion in the cooling circuit. The last part is the design of a new lighting system using LED lamps.