In September 2020, Northeast China suffered three unprecedented typhoons in half a month, and there was freezing rain in early November, all of which led to the large-scale urban power failure. The occurrence of these phenomena makes people directly see climate change and its impact on the living environment of human beings. Many studies have shown that the cause of climate change is the increase of artificial greenhouse gas emissions since industrialization. In addition to the increase of extreme weather disasters, the most direct manifestations of climate change are the rising temperature, droughts, and rising sea levels. The building sector accounts for 39% of global greenhouse gas emissions and 36% of energy consumption. To ensure the long-term integrity and normal operation of buildings, we need to understand the impact of climate on buildings, and how to deal with it. This paper reviews the literature on climate change and building energy by searching search engines and literature databases. For extreme weather, most literature talks about the impact of power failure, the main strategy is to improve reliability, resilience, sustainability, and robustness, it can help reduce losses and recover as soon as possible. On the other hand, the methods of adaptation to and mitigation of non-disaster weather are reviewed from the perspective of sustainability. This paper mainly reviews the methods of passive technology and strategy for exemplary buildings, building envelope, passive ventilation, lighting/shading, solar energy, bioenergy, dehumidification, passive cooling, and design strategy. According to the local climate, the geographical characteristics of the building, to develop comprehensive passive technology and strategy, can meet or close to meet their energy saving, emission reduction, comfort needs. This paper can provide a technical and strategic reference for the building sector to deal with climate change. / <p></p><p>Via online ZOOM meeting Presentation</p><p></p><p></p><p></p><p></p><p></p><p></p>

Wireless technology is used daily across the globe. A very common wireless technology is Bluetooth. The Bluetooth technology exists everywhere, from cars to mobile phones and even kitchen appliances. Recently, Bluetooth Low Energy has added support for another physical layer, LE 2M PHY. This physical layer is supposed to be faster and more energy efficient than its predecessor, LE 1M PHY, with a decrease in range. Because of this new physical layer, Bluetooth Low Energy can now compete with Bluetooth Classic during data transmission, in both speed and energy efficiency. This thesis aims to find the breaking point where Bluetooth Low Energy becomes less energy efficient than Bluetooth Classic, in relation to bit rate speed and total amount of bytes sent. Before experiments were conducted, multiple iterations of an artifact had to be done to end up with an artifact that provides valid and reliable data. The experiments were then conducted by changing the bit rate speed and sending different amounts of bytes. The results from the experiments show that Bluetooth Classic is practically both faster and more energy efficient with its fastest modulation than Bluetooth Low Energy is with LE 2M PHY enabled, even though this should not be the case theoretically. Bluetooth Classic is overall more energy efficient than Bluetooth Low Energy and thus the conclusion of this study is that no breaking points between the two technologies exist.

In recent years, eco–city as a sustainable urban model has gained increasing prevalence and evolved into a hegemonic urban discourse. As a future vision of urban transformation, eco–city is being increasingly translated into concrete projects, strategies, and policies, mainstreaming urban sustainability and being replicated and proliferated across the world. This study aims to examine, by means of a discursive analytical approach, the construction of eco–city in the Swedish urban context – urban planning and development – with a particular emphasis on definitional and thematic issues, cultural bias, selectivity, framing, and political action. I use six analytical devices to guide the analysis of four documents as an empirical material. Findings show that the construction of eco–city in the Swedish urban context entails aspects of other sustainable urban models: smart city, sustainable city, green city, and compact city, making eco–city as an umbrella metaphor for such models. Also, only combining all projects, it is clear that eco–city has evolved into a comprehensive vision, embracing most of the requirements and norms set for a city to be ecological. While the concept of eco–city tends to incorporate social and cultural dimensions of urban sustainability, the prime focus remains on economic and environmental aspects – in other words, social considerations are marginal compared to economic and environmental ones. Moreover, the discourse of eco–city draws on and is informed by an array of established discourses. Building on previous discursive constructions of reality, it changes urban reality – aspects of its economic and environmental dimensions, by generating new ways of thinking about urban practices through new amalgamations of established discourses. The technological orientation of eco–city has links to urban–economic–political processes of regulation as well as involves selective framing in terms of discursive interpretation of urban–environmental crises as material processes, recontextualization of urban- economic imaginaries, reference to particular meta–discourses, and privileging of particular discursive chains. Technologically-oriented eco–city can be conceptualized as a specific urban practice which is contingent upon hegemonic discourses on the economic, technological and environmental regulation in relation to urbanization and on the agency of various actors advocating energy efficiency and green technologies and forming alliances on sustainable urban issues. Furthermore, the discourse of eco–city is exclusionary, in that it leaves out some topics and facts relating to the negative direct and indirect environmental effects of the so–called green and energy efficiency technologies. In addition, the discourse of eco–city is shaped by cultural frames associated with environmental and climate awareness and the role of technology in enabling and catalyzing sustainable urban transformation. Finally, using different mechanisms, political action has a great impact on the discourse of eco–city in relation with the environment, climate change, and shifts to low–carbon/low-energy cities. It plays a role in the expansion and success of eco–city.

Current mobile network architecture is facing a big challenge as the traffic demands have been increasing dramatically these years. Explosive mobile data demands are driving a significant growth in energy consumption in mobile networks, as well as the cost and carbon footprints [1]. In 2010, China Mobile Research Institute proposed Cloud Radio Access Network (C-RAN) [2], which has been regarded as one of the most promising architecture to solve the challenge of operators. In C-RAN, the baseband units (BBU) are decoupled from the remote radio units (RRH) and centralized in one or more locations. The feasibility of combination of implementing the very tight radio coordination schemes and sharing baseband processing and cooling system resources proves to be the two main advantages of C-RAN compared to traditional RAN. More importantly, mobile operators can quickly deploy RRHs to expand and make upgrades to their networks. Therefore, the C-RAN has been advocated by both operators and equipment vendors as a means to achieve the significant performance gains required for 5G [3]. However, one of the biggest barriers has shown up in the deployment of C-RAN as the novel architecture imposes very high capacity requirement on the transport network between the RRHs and BBUs, which is been called fronthaul network. With the implementation of 5G wireless system using advanced multi-antenna transmission (MIMO), the capacity requirement would go further up, as well as the power consumption. One solution has been proposed to solve the problem is to have the baseband functions divided, partially staying with RRHs and other functions would be centralized in BBU pool. Different splitting solutions has been proposed in [4] [5] and [6]. In this thesis work, we choose four different splitting solutions to build four CRAN architecture models. Under one specific case scenario with the fixed number of LTE base stations, we calculate the transport capacity requirement for fronthaul and adopt three different fronthaul technology. The power consumption is calculated by adding up the power utilized by RRHs, fronthaul network and baseband processing. By comparing the numerical results, split 1 and 2 shows the best results while split 2 is more practical for dense cell area, since split 1 requires large fronthaul capacity. The fronthaul transport technology can be decided according to different density of base stations. TWDM-PON shows better energy performance as fronthaul network when the capacity requirement is high, compared to EPON. However, for larger number of BSs, mm-Wave fronthaul is a better solution in terms of energy efficiency, fiber saving and flexibility.

Följande studie är ett examensarbete utfört vid Kungliga Tekniska Högskolan våren 2021 på Uppdrag av ett energiföretag. Studien syftar till att undersöka och jämföra effekttoppar i två olika fastigheter samt studera hur en reducering av effekttopparna påverkar den årliga elkostnaden för fastighetsägaren. Rapporten ämnar även att översiktligt undersöka om batteridrift skulle kunna vara en möjlig lösningsmetod för att möjliggöra denna reducering. Medvetenheten kring nutidens miljöproblem har resulterat i att allt fler efterfrågar hållbara energilösningar till sina fastigheter. Många siffror indikerar att elpriset i framtiden kommer att öka samtidigt som konsumtionen av el även förutspås öka. Ett av de största problemen med dagens elkonsumtion är att den inte är jämnt fördelad och att det därför bildas effekttoppar de tider på dygnet då fastigheterna konsumerar som mest elektricitet. Det leder till högre priser och eftersom många befintliga elabonnemangen idag baserar sina priser på när fastigheter konsumerar som mest, har många elnätsbolag en så kallad månadseffektavgift. Detta innebär att en stor del av den fasta elkostnaden baseras enbart på det högst uppmätta värdet för innevarande månad. För att undersöka hur mycket en reducering av effekttopparna påverkar den årliga elkostnaden skapades Exceldokument där två olika fastigheters elförbrukning och abonnemangskostnader fördes in. Studien visade att effekttoppar kan reduceras med rätt teknik, men en djupare analys behöver göras för hur den tekniska lösningen ska se ut. En djupare analys behöver göras för att ta reda på vilken dimensionering av batterier som är lämplig och troligtvis skulle den verkliga återbetalningstiden vara mycket kortare då de största besparingarna kan göras inom andra områden som till exempel frekvensreglering och effektförsäljning. Olika scenariosimuleringar i exceldokumentet visade att en reduktion av effekttopparna med 50% kan minska den årliga besparingen med upp till 10%. / The following study is a bachelor thesis carried out at the Royal Institute of Technology on behalf of an energy company who is based in Stockholm. The aim of the study is to investigate and compare power peaks in two different real estate properties. The report will also study how a reduction of the power peaks affects the annual electricity cost. Finally, the report intends to briefly examine if battery storage could be a possible solution to enable this reduction in costs. The growing awareness of today's environmental problems has resulted in a greater demand among real estate owners for sustainable energy solutions. Data indicates that both the price and the consumption of electricity will increase in the future. One of the biggest problems with today's electricity consumption is that it is not evenly distributed, and power peaks are formed when users consume the most electricity. These peaks causes electricity prices to rise and since many existing electricity subscriptions today base their prices on when properties consume the most, this means that consumers pay higher prices than necessary. To investigate how much a reduction in power peaks would affect the annual electricity cost, an Excel document was created in which the electricity consumption and subscription costs of two different properties were entered. The study shows that power peaks can be reduced with the right technology, but a more accurate analysis needs to be executed to find out how the technical solution should be designed. A key part of this solution is a more thorough analysis of the necessary dimensioning of batteries for the property, and it is likely that payback times suggested in this report could be even shorter given that even bigger savings can be made in areas other than those examined in this study, such as frequency control and power sales. Various scenario simulations in the Excel document showed that a reduction of the power peaks by 50 percent can reduce the annual savings by up to 10 percent.

Several CO2 transcritical booster systems in supermarkets use the potential of integrating geothermal storage, enabling subcooling during warm climate conditions as well as being a heat source during cold climate conditions. First of all, field measurements of one of these systems located in Sweden were analysed with particular focus on the heat-recovery performance. The best theoretical operational strategy was compared to the one really implemented and the differences in the annual energy usage were assessed through modelling. The results show that an alternative to the best theoretical operational strategy exists; heat can be extracted from the ground while low-temperature heat is rejected by the gas cooler. Such an alternative strategy has important technical advantages with a negligible increment of the energy usage. In the second part of this work, the benefits of geothermal subcooling were evaluated. Applying the BIN hours method, it was demonstrated that this system is expected to save on average roughly 5% of the total power consumption, in Stockholm’s climate. The models utilized for the winter and summer season were combined to find the relationship between geothermal storage size and annual energy savings. In this way, it was possible to calculate the present value of the operational savings for the study case. Furthermore, a general methodology for assessing the economic feasibility of this system solution is presented. Finally, several scenarios were investigated to produce parametric curves and to perform a sensitivity analysis. Comparing the results with the typical Swedish prices for boreholes, the cases where this system solution is economically justified were identified. These are supermarkets with a Heat Recovery Ratio (HRR) higher than the average. For examples, supermarkets supplying heat to the neighbouring buildings (considering the Stockholm’s climate, systems with an annual average HRR of at least 70%). Relying only on savings from subcooling was found to be not enough to justify a geothermal storage, a not-negligible amount of heat must be extracted in winter. Finally, some interesting concepts and alternatives to a geothermal integration are presented to point out relevant future work.

<p>As a promising new technology, organic photovoltaics (OPVs) have been widely studied recently. To improve the device efficiency for commercial use of 10%, a number of attempts have been made in my research. The ultra-low frequency AC field was first employed, to align p/n polymers during fabrication. The resulting devices showed 15% increase in device efficiency, attributed to the optimized morphology and enlarged p/n interface. During the improvement process, dual nanostructures of the polymers were found, the highly oriented layer and the randomly distributed part, which provided a better understanding of the OPVs under the AC field alignment.</p> <p>The OPV stability was then studied by impedance measurements, to track multi-interface degradation without breaking the device. It was found the degradation of p/n junction was attributed to the deteriorated morphology and oxidized polymers, whereas the semiconductor/metal interface changed by producing metal oxides as degradation products.</p> <p>The dramatic contrast between the bilayer and bulk heterojunctions (BHJ) was at last investigated by capacitance measurements in vacuum. The existing models of the BHJs had difficulty explaining the higher overall capacitance, compared with that from the bilayer devices. The resulting puzzling charge density was clarified by separating the measured capacitance into two parallel components, one from the space charge of the proposed Schottky junction, and the other from the dark dipoles presumably formed spontaneously across the donor/acceptor interface.</p> / Doctor of Philosophy (PhD)

<p>In this thesis we consider low complexity downlink traffic scheduling for green vehicular roadside infrastructure. In multiple roadside unit (RSU) deployments, the energy provisioning of the RSUs may differ, and it is therefore desirable to balance RSU usage from a normalized energy viewpoint. We consider both splittable and unsplittable RSU assignment scheduling (SRA and URA). We first derive an offline integer linear programming bound for the normalized min-max RSU energy usage, which can be solved for a given input sample function. We then show that in the SRA case there is a polynomial complexity 2-approximation bound for the normalized min-max energy schedule. These bounds are used for comparisons with several proposed online scheduling algorithms. The first scheduler is a low complexity Greedy Online Algorithm (GOA) that makes greedy RSU selections followed by minimum energy time slot assignments. A normalized min-max online algorithm is then proposed (TOAA) which is an online version of the 2-approximation bound for SRA scheduling. Then, the Greedy Flow Graph Algorithm (GFGA), which makes greedy RSU selections followed by time slots reassignment whenever a new vehicle is assigned to the same RSU. This is done using a locally optimum integer linear program that can be efficiently solved using a minimum cost flow graph. Two low complexity algorithms are then introduced based on a potential function scheduling approach. The One-Objective algorithm, uses a primary objective based on normalized min-max energy. The second, the Bi-Objective algorithm, uses the same primary objective combined with a total energy secondary objective. These algorithms have provable performance guarantees, in that their worse-case competitive ratio performance is upper bounded. Results from a variety of experiments show that the proposed scheduling algorithms perform well. In particular, we find that in the SRA case, the TOAA and GFGA algorithms perform very close to the lower bound, but at the expense of having to reassign time slots whenever a new vehicle arrives. In the URA case, our low complexity One-Objective algorithm performs better than the others over a wide range of traffic conditions.</p> / Master of Applied Science (MASc)

<p>Smart scheduling can be used to reduce infrastructure-to-vehicle</p> <p>energy costs in delay tolerant vehicular</p> <p>networks (Hammad et al., 2010).. In this thesis we show that by combining</p> <p>this with vehicle-to-vehicle (V2V) forwarding, energy efficiency can</p> <p>be increased beyond that possible in the single hop case. This is</p> <p>accomplished by having the roadside infrastructure forward packets</p> <p>through vehicles which are in energy favourable locations. We first</p> <p>derive offline bounds on the downlink energy usage for a given input</p> <p>sample function when V2V forwarding is used. Separate bounds are given</p> <p>for the off-channel and in-channel forwarding cases. These bounds are</p> <p>used for comparisons with a variety of proposed online scheduling</p> <p>algorithms. The paper then introduces online algorithms for both</p> <p>fixed bit rate and variable bit rate air interface options. The first</p> <p>algorithm is based on a greedy local optimization (GLOA). A version of</p> <p>this algorithm which uses a minimum cost flow graph scheduler is also</p> <p>introduced. A more sophisticated algorithm is then proposed which is</p> <p>based on a finite window group optimization (FWGO). Versions of these</p> <p>algorithms are also proposed which use in-channel vehicle-to-vehicle</p> <p>scheduling. The proposed algorithms are also adapted to the variable</p> <p>bit rate air interface case. Results from a variety of experiments</p> <p>show that the proposed scheduling algorithms can significantly improve</p> <p>the downlink energy requirements of the roadside unit compared to the</p> <p>case where vehicle-to-vehicle packet forwarding is not used. The</p> <p>performance improvements are especially strong under heavy loading</p> <p>conditions and when the variation in vehicle communication</p> <p>requirements or vehicle speed is high.</p> / Master of Applied Science (MASc)

New windows are rated based on their energy performance during the use phase. This rating neglects the overall environmental impact caused by raw material extraction, manufacturing, maintenance and disposal. Due to the number of residential window replacements occurring today in the United States, there is a growing need to quantify the sustainability of window preservation as an alternative to window replacement. This study assessed the environmental impact of historic wood window restoration versus window replacement for the entire "cradle to grave" life cycle of the window assembly. This study focused on a typical, mid-twentieth century housing development in the Northeast United States using four window configurations as follows: 1. Restored original wood window with a new exterior aluminum storm window; 2. PVC replacement window; 3. Aluminum-clad wood replacement window; 4. Wood replacement window. The dissertation assessed the life cycle of window configurations using GaBi Software. The life cycle inventories were analyzed using the TRACI 2.1 impact method which translated the environmental consequences of the life cycle assessment processes into quantifiable environmental impacts. The dissertation also considered window thermal performance and life cycle costs. When considering life cycle environmental impacts, thermal performance, energy savings and material costs, the results indicated that wood window restoration was the best option when compared to replacement windows considered in this study; however, the results indicated that building service life and window service life assumptions could impact results. Thermal performance testing of windows revealed that window restoration techniques undertaken in this study improved the window's overall thermal performance. The testing also indicated that the effects of air infiltration had minimal influence on the performance of the restored window assembly when compared to a high performance replacement window. The results of the energy model exhibited only a small annual energy savings between the restored window assembly and a high performance replacement window. The payback cost analysis revealed that, while there was an immediate financial benefit of window replacement with the PVC option, window replacement frequency and overall life cycle environmental impacts would favor the restored window option. / Civil Engineering