The impeding climate change challenge urges for a reduction of energy use in the built environment. Buildings account for nearly 40% of the total energy use and about 35% of the greenhouse gas emissions in Europe. EU member states are required to improve the energy efficiency of the existing building stock, for example by sharpening building regulations and developing enforcement schemes. Since energy efficiency retrofits can affect irreplaceable values in heritage buildings, heritage buildings are often excluded from mandatory demands aiming at reducing the energy use in buildings. However, saving energy have gradually become embraced by the conservation community and heritage buildings with are seen as part of the solution. This licentiate thesis discusses the methods to identify heritage significance in a building and how the underlying theory determines different scenarios in a energy retrofitting process. The choice of conservation theory and conservation approach will affect the success the energy retrofitting process and determine how much the energy use that can be reduced. This thesis therefore suggests a framework to understand the different interpretation of the impacts that one could exert either by having an Objectivistic or Relative conservation value approach.. Based on this framework, a decision-support tool is developed to further detail the impacts of such approaches for different energy measures. Other results show that a majority of reviewed research publications focused on the operational energy in a building and only a few were concerned with energy use over the entire life- cycle of a building. These analyses are used to evaluate where most energy savings can be made, and often pinpoint weak spots in the building’s envelope or technical system. If it was mentioned at all, the influence of cultural and historical factors on energy efficiency measures as applied to heritage buildings tended to be assessed only briefly. Indeed, the majority does not describe conservation principles or even mention the methodology used – if any – for assessing or defining heritage values. Instead, researchers often show an explicit (sometimes an implicit) understanding of conservation as essentially something that is not destructive of original construction material and hence the authenticity of a building. This licentiate thesis is a compilation thesis, consisting of one separate sub-study, one literature review and an extended cover essay. The study is oriented towards a Swedish and European context, especially when it comes to climate conditions and discussions on building regulations and the theory and practice of architectural conservation. It addresses the growing research field of energy efficiency in heritage buildings and the thesis aims to contribute to an increased understanding on how the process of assessment and evaluation of heritage significance in buildings affects the making of heritage buildings more energy efficient. The main research question is: How do different approaches for assessing and evaluating heritage significance in buildings affect possible technical energy saving measures in heritage buildings? / Klimatförändringarna driver utvecklingen mot att energianvändningen i den byggda miljön behöver minska. Byggnader står för nästan 40% av den totala energianvändningen och cirka 35% av utsläppen av växthusgaser i Europa. EUs medlemsländer är bundna att förbättra energieffektiviteten hos befintliga byggnader, till exempel genom att skärpa byggreglerna och utveckla handlingsplaner. Eftersom energieffektiviseringar kan påverka värden i kulturhurhistoriska byggnader, är dessa ofta undantagna från krav som syftar till att minska energianvändningen i byggnader. Energibesparing och resurshushållning har gradvis blivit omfamnad av kulturmiljösektorn och kulturhistoriska byggnader betraktas allt mer som en del av lösningen på klimatförändringarna. I licentiatavhandlingen diskuteras metoderna för att identifiera kulturhistoriska värden i en byggnad och hur den underliggande teorin påverkar olika scenarier i en energieffektiviseringprocess. Valet av bevarandeteori och bevarandestrategi påverkar framgångsfaktorn i energieffektivseringen och hur mycket energianvändningen i en kulturhistorisk byggnad kan minskas. I denna avhandling föreslås därför ett teoretiskt ramverk för att förstå effekterna av de olika kulturhistoriska bedömningar som kan göras, antingen genom att använda ett objektivistiskt eller en relativ syn på hur en en byggnads kulturhistoriska värden skapas och bäst bevaras. Utifrån detta teoretiska ramverk har ett stöd för beslutsfattande utvecklats för att ytterligare beskriva effekterna av de olika bevarandestrategiernas påverkan på implementeringen av olika energieffektiviserande åtgärder. Andra resultat visar att en majoritet av de granskade forskningspublikationerna fokuserade på den operativa energin i en byggnad och bara ett fåtal gällde energianvändning under hela livscykeln i en byggnad. Dessa analyser används för att utvärdera var de flesta energibesparingar kan göras och ofta identifiera svaga punkter i byggnadens klimatskal eller tekniska system. Om det nämndes alls tenderade inflytandet av kulturella och historiska faktorer på energieffektivitetsåtgärder som tillämpas på arvsbyggnader endast att bedömas kortfattat. Faktum är att majoriteten av de genomgångna publikationerna inte beskriver bevarandeprinciper och inte nämner den metod som används för att bedöma eller definiera kulturhistoriska värden. Istället används ofta en explicit (ibland en implicit) förståelse för bevarande som i huvudsak något som inte förstör ursprungligt material och därmed autenticitet i en byggnad. Denna licentiatavhandling består av en separat undersökning, en litteraturöversikt och en utökad kappa. Studien är inriktad på ett svenskt och europeiskt sammanhang, särskilt när det gäller klimatförhållanden och diskussioner om byggregler och teori och praktik för kulturhistoriskt bevarande av byggnader. Den är en del av det växande forskningsområdet energieffektivisering i kulturhistoriska byggnader och avhandlingen syftar till att bidra till en ökad förståelse för hur utvärderingen av kulturhistoriska värden i byggnader påverkar arbetet med att göra dem mer energieffektiva. Huvudforskningsfrågan är: Hur påverkar olika metoder för bedömning och utvärdering av kulturhistoriska värden energibesparande åtgärder i kulturhistoriska byggnader?

The manufacturing sector is one of the significant consumers of electricity, with about 42.3% (8249 TWh) of the global electricity consumption attributable to this sector. This electricity is generated from fossil fuels at the power stations, resulting in increased CO2 emission and subsequently global warming. Thus, energy efficiency could play a vital role in reducing electrical energy demand and environmental impacts in the manufacturing sector. Mechanical machining is one of the widely used techniques in manufacturing. Machine tools consist of auxiliary units, spindle, feed axes including the x-axis, y-axis, z-axis, and the tool change system which are the main electrical energy consumers. The feed axes control the relative motion between the workpiece and cutter, and also determine the workpiece geometry. In literature, a number of studies focused on the machining process as a whole, while the energy demand for axis and toolpaths was relatively unexplored. This PhD research was aimed at assessing the electrical energy demand in mechanical machining, focusing on feed motions and toolpaths in order to identify energy saving strategies of the machine tool. To achieve this, a current measurement device was used to acquire the current and voltage, from which the power and electrical energy requirements were evaluated. This study included (i) energy consumption analyses of the machine tool in different feed axes directions, (ii) cutting of components in different axes orientations (iii) and electrical energy demand studies of different toolpath strategies. From the study, a new method and model for predicting the electrical energy demand of feed axes was developed. This model encompasses the weights of feed axes, machine tool vice, and workpiece placed on the machine table. Moreover, the newly developed feed axes energy demand model was integrated into other energy consumption models to predict the energy demand for toolpaths. CNC toolpaths are generated manually or by computer aided manufacturing (CAM). Enabling an energy rating of CNC toolpaths is vital to be able to quantify energy demand, compare toolpaths, and develop energy demand reduction strategies. The results show that machining along the x-axis which carries minimal weights significantly reduced the energy demand of the feed drive, which in turn reduces the non-cutting energy demand of the machine tool. Thus, this Thesis contributes to the improvement of energy efficiency in machining through the development of a new and novel model and method for predicting the feed axes energy demand; determining the most efficient axes and component orientation; as well as the most efficient toolpath strategy for minimal energy demand in machining. This PhD Thesis has laid the foundation model and information source for a post processor to estimate energy demand from CNC toolpaths. Such a capability was not available in CAM software or on CNC machines.

Approximately 30% of the UK s housing stock is comprised of older, solid wall buildings. Solid walls have no cavity and were built without insulation; therefore these buildings have high heat loss, can be uncomfortable for occupants throughout the winter and require an above-average amount of energy to heat. Solid wall buildings can be made more energy efficient by retrofitting internal wall insulation (IWI). However, there is little empirical evidence on how much energy can be saved by insulating solid wall buildings and there are concerns that internal wall insulation could lead to overheating in the summer. This thesis reports measured results obtained from a unique facility comprised of a matched pair of unoccupied, solid wall, semi-detached houses. In the winter of 2015 one house of the pair was fitted with internal wall insulation then both houses had their thermal performance measured to see how differently they behaved. Measuring the thermal performance was the process of measuring the wall U-values, the whole house heat transfer coefficient and the whole house airtightness of the original and insulated houses. Both houses were then monitored in the winter of 2015, monitoring was the process of measuring the houses energy demand while using synthetic occupancy to create normal occupancy conditions. In the summer of 2015 indoor temperatures were monitored in the houses to assess overheating. The monitoring was done firstly to see how differently an insulated and an uninsulated house perform under normal operating conditions: with the blinds open through the day and the windows closed. Secondly, a mitigation strategy was applied to reduce high indoor operative temperatures in the houses, which involved closing the blinds in the day to reduce solar gains and opening the windows at night to purge warm air from the houses. The original solid walls were measured to have U-values of 1.72 W/m2K, while with internal wall insulation the walls had U-values of 0.21 W/m2K, a reduction of 88%. The house without IWI had a heat transfer coefficient of 238 W/K; this was reduced by 39% to 144 W/K by installing IWI. The monitored data from winter was extrapolated into yearly energy demand; the internally insulated house used 52% less gas than before retrofit. The measured U-values, whole house heat loss and energy demand were all compared to those produced from RdSAP models. The house was found to be more energy efficient than expected in its original state and to continue to use less energy than modelled once insulated. This has important implications for potential carbon savings and calculating pay-back times for retrofit measures. In summer, operative temperatures in the living room and main bedroom were observed to be higher, by 2.2 oC and 1.5 oC respectively, in the internally insulated house in comparison to the uninsulated house. Both of these rooms overheated according to CIBSE TM52 criteria; however the tests were conducted during an exceptionally warm period of weather. With the simple mitigation strategy applied the indoor operative temperature in the internally insulated house was reduced to a similar level as observed in the uninsulated house. This demonstrates that any increased overheating risk due to the installation of internal wall insulation can be mitigated through the use of simple, low cost mitigation measures. This research contributes field-measured evidence gathered under realistic controlled conditions to show that internal wall insulation can significantly reduce the energy demand of a solid wall house; this in turn can reduce greenhouse gas emissions and could help alleviate fuel poverty. Further to this it has been demonstrated that in this archetype and location IWI would cause overheating only in unusually hot weather and that indoor temperatures can be reduced to those found in an uninsulated house through the use of a simple and low cost mitigation strategy. It is concluded that IWI can provide a comfortable indoor environment, and that overheating should not be considered a barrier to the uptake of IWI in the UK.

The aim of this paper is twofold: 1) to examine the determinants of residential energy expenditures and compare them on a regional level; and, 2) attempt to identify and measure the effect of possible principal-agent (PA) problems on residential energy efficiency in Austria. The results of this paper are partially based on findings from a master's thesis, which focused more directly on the PA problem. This paper expands on those results to include regional aspects in energy expenditures. A conditional demand model is regressed on a large number of variables representing housing characteristics, socioeconomic factors, occupancy type, and regional characteristics sourced from the EU Statistics on Income and Living Conditions dataset. The analysis indicates that significant regional differences exist in the determinants of residential energy expenditures and that PA problems appear to be an unimportant factor in energy efficiency in Austria, even at the regional level. The paper concludes with some possible explanations as to why this is the case.

Denna rapport utgör ett examensarbete vid Umeå Universitet. Målet med denna rapport är att visa val av metod, tillvägagångssätt och tidsåtgång enligt Miljöbyggnad för befintliga byggnader. Miljöbyggnad är ett certifieringssystem där indikatorer för energi, miljö och material undersöks. Klarar byggnaden kraven får den en Miljöbyggnadscertifiering. \\ \\ Miljöbyggnad startade redan 2003, vid dåvarande namn, Miljöklassad byggnad och var ett samarbete mellan kommun, företag och regering för en hållbar utveckling inom bygg- och fastighetssektorn. Detta var kopplat till de miljömål som regeringen satte upp 1999.\\ \\ De indikatorer som undersökts i detta arbete har varit de kopplade till energi och miljö. Enligt instruktionerna för Miljöbyggnad kan många av indikatorernas resultat redovisas genom simulerade värden eller uppmätta/beräknade värden. \\ De resultat som är kopplade till indikatorerna har undersökts genom mätning, beräkning och simulering då jämförelse mellan metoder har gjorts. \\ \\ Arbetet har resulterat i ett förslag om tillvägagångssätt där företaget i samband med en energideklaration kan göra en grov uppskattning huruvida en Miljöbyggnadsprocess kan göras. Visar byggnaden sig lämplig för en sådan certifiering är förslaget att insamling av nödvändig information om byggnaden sker i första steget. Det innefattar allt från ritningar av hela fastigheten till inventering av fastighetens interna laster. Vidare ska byggnadens energi- och miljödata simuleras för att kunna jämföras mot Miljöbyggnads krav. Detta tillvägagångssätt bedöms vara mest lämpligt för de flesta fastigheter.  \\ Det finns enklare sätt att bedöma vissa av indikatorerna men det kräver samtidigt att ett rum/lokal uppfyller vissa förutsättningar. / This report is a bachelor thesis at Umeå University. The purpose of this report is to show the choice of method, approach and timeframe according to the environmental building for existing buildings. \\ \\ Miljöbyggnad is a certification system in which indicators for energy, environment and materials are examined. If the building meets the requirements, it will receive an environmental certification. Miljöbyggnad started already in 2003, when it was called the Miljöklassad byggnad and was a cooperation between the municipality, companies and government for sustainable development in the construction and real estate sector. This was linked to the environmental goals set by the government in 1999. \\ \\The indicators investigated in this work have been linked to energy and the environment. According to the instructions for environmental construction, many of the indicators can be reported by simulated values or measured/calculated values. \\ The results associated with the indicators have been investigated by measurement, calculation and simulation where comparison of methods has been made. \\ \\ The work has resulted in a proposal for ways in which the company, in connection with an energy declaration, can make a rough estimate of whether an environmental construction process can be done. If the building is considered suitable for such certification, the proposal is that collection of necessary information about the building will take place in the first step. It includes everything from drawings of the entire property to inventory of the property's internal loads. Furthermore, the energy and environmental data of the building will be simulated in order to be able to compare against environmental building requirements. This approach is considered to be most appropriate for most properties. \\ There are easier ways to judge some of the indicators, but it also requires a room/officespace to meet certain conditions.

Os atuais sistemas de HPC tem realizado simulações mais complexas possíveis, produzindo benefícios para diversas áreas de pesquisa. Para atender à crescente demanda de processamento dessas simulações, novos equipamentos estão sendo projetados, visando à escala exaflops. Um grande desafio para a construção destes sistemas é a potência que eles vão demandar, onde perspectivas atuais alcançam GigaWatts. Para resolver este problema, esta tese apresenta uma abordagem para aumentar a eficiência energética usando recursos de HPC, objetivando reduzir os efeitos do desequilíbrio de carga e economizar energia. Nós desenvolvemos uma estratégia baseada no consumo de energia, chamada ENERGYLB, que considera características da plataforma, irregularidade e dinamicidade de carga das aplicações para melhorar a eficiência energética. Nossa estratégia leva em conta carga computacional atual e a frequência de clock dos cores, para decidir entre chamar uma estratégia de balanceamento de carga que reduz o desequilíbrio de carga migrando tarefas, ou usar técnicas de DVFS par ajustar as frequências de clock dos cores de acordo com suas cargas computacionais ponderadas. Como as diferentes arquiteturas de processador podem apresentam dois níveis de granularidade de DVFS, DVFS-por-chip ou DVFS-por-core, nós criamos dois diferentes algoritmos para a nossa estratégia. O primeiro, FG-ENERGYLB, permite um controle fino da frequência dos cores em sistemas que possuem algumas dezenas de cores e implementam DVFS-por-core. Por outro lado, CG-ENERGYLB é adequado para plataformas de HPC composto de vários processadores multicore que não permitem tal refinado controle, ou seja, que só executam DVFS-por-chip. Ambas as abordagens exploram desbalanceamentos residuais em aplicações interativas e combinam balanceamento de carga dinâmico com técnicas de DVFS. Assim, eles reduzem a frequência de clock dos cores com menor carga computacional os quais apresentam algum desequilíbrio residual mesmo após as tarefas serem remapeadas. Nós avaliamos a aplicabilidade das nossas abordagens utilizando o ambiente de programação paralela CHARM++ sobre benchmarks e aplicações reais. Resultados experimentais presentaram melhorias no consumo de energia e na demanda potência sobre algoritmos do estado-da-arte. A economia de energia com ENERGYLB usado sozinho foi de até 25% com nosso algoritmo FG-ENERGYLB, e de até 27% com nosso algoritmo CG-ENERGYLB. No entanto, os desequilíbrios residuais ainda estavam presentes após as serem tarefas remapeadas. Neste caso, quando as nossas abordagens foram empregadas em conjunto com outros balanceadores de carga, uma melhoria na economia de energia de até 56% é obtida com FG-ENERGYLB e de até 36% com CG-ENERGYLB. Estas economias foram obtidas através da exploração do desbalanceamento residual em aplicações interativas. Combinando balanceamento de carga dinâmico com DVFS nossa estratégia é capaz de reduzir a demanda de potência média dos sistemas paralelos, reduzir a migração de tarefas entre os recursos disponíveis, e manter o custo de balanceamento de carga baixo. / Current HPC systems have made more complex simulations feasible, yielding benefits to several research areas. To meet the increasing processing demands of these simulations, new equipment is being designed, aiming at the exaflops scale. A major challenge for building these systems is the power that they will require, which current perspectives reach the GigaWatts. To address this problem, this thesis presents an approach to increase the energy efficiency using of HPC resources, aiming to reduce the effects of load imbalance to save energy. We developed an energy-aware strategy, called ENERGYLB, which considers platform characteristics, and the load irregularity and dynamicity of the applications to improve the energy efficiency. Our strategy takes into account the current computational load and clock frequency, to decide whether to call a load balancing strategy that reduces load imbalance by migrating tasks, or use Dynamic Voltage and Frequency Scaling (DVFS) technique to adjust the clock frequencies of the cores according to their weighted loads. As different processor architectures can feature two levels of DVFS granularity, per-chip DVFS or per-core DVFS, we created two different algorithms for our strategy. The first one, FG-ENERGYLB, allows a fine control of the clock frequency of cores in systems that have few tens of cores and feature per-core DVFS control. On the other hand, CGENERGYLB is suitable for HPC platforms composed of several multicore processors that do not allow such a fine-grained control, i.e., that only perform per-chip DVFS. Both approaches exploit residual imbalances on iterative applications and combine dynamic load balancing with DVFS techniques. Thus, they reduce the clock frequency of underloaded computing cores, which experience some residual imbalance even after tasks are remapped. We evaluate the applicability of our approaches using the CHARM++ parallel programming system over benchmarks and real world applications. Experimental results present improvements in energy consumption and power demand over state-of-the-art algorithms. The energy savings with ENERGYLB used alone were up to 25%with our FG-ENERGYLB algorithm, and up to 27%with our CG-ENERGYLB algorithm. Nevertheless, residual imbalances were still present after tasks were remapped. In this case, when our approaches were employed together with these load balancers, an improvement in energy savings of up to 56% is achieved with FG-ENERGYLB and up to 36% with CG-ENERGYLB. These savings were obtained by exploiting residual imbalances on iterative applications. By combining dynamic load balancing with the DVFS technique, our approach is able to reduce the average power demand of parallel systems, reduce the task migration among the available resources, and keep load balancing overheads low.

Energy demand reduction has become a global issue involving all countries, including China. As major energy consumers in today s society, the need for buildings to be built and operated more energy efficiently is well recognized. In 1995, the national standard on building energy efficiency in China (JGJ 26-95) was refined and updated to become the new residential Buildings standard (JGJ 26-2010) published in 2010. In the new version, many changes have been made to support the construction of more energy efficient buildings in China. For example, in the new standard, all buildings are highly recommended to install personal control on the heating system, such as by Thermostatic Radiator Valves (TRVs), together with pay for what you use tariffs. Previous practice comprised uncontrolled heating with payment based on floor area. In order to reduce building energy consumption, Chinese government has revised the Chinese building design standard. In the new guide the use of individual room temperature control is highly recommended for new and refurbishment buildings. However, evidence to quantify the extent to which this improvement impact upon on the building energy consumption is currently lacking. This thesis evaluates the impact of updated building design standards on thermal conditions and energy consumption in Chinese residential buildings. In order to evaluate the impact on the building energy consumption, two types of residential buildings have been chosen, one complying with the old Chinese building design standard, while the other complies with the new standard. The study was carried out in seven apartments in each type of building, a total of fourteen apartments and comprised with a longitudinal monitoring of indoor air temperature, outdoor air temperature, window position and energy consumption of each apartment. The impact of the new design standard has been evaluated in relation to a number of aspects, that include building construction, indoor thermal environment, occupant behaviour, thermal comfort and building energy consumption. It is concluded that updating the building design standard has had a positive influence on the building conditions and energy consumption. Furthermore, a thermal comfort survey was carried out in both new and old apartments according to updated standards. The results show that the Predicted Mean Vote (PMV) model has a efficiently adequate predictor of occupants thermal comfort in both type of apartments. Thereby allowing confirmation that the new control refine did not compromise on thermal comfort. The percentage of acceptable of occupants is higher in new apartments compared with the old apartments.

This study examined the Lake of Egypt Power Plant operated by Southern Illinois Power Cooperative located on the Lake of Egypt south of Marion, IL. The facility has a 173 MW rated turbine operating on a pulverized coal cyclone boiler and three 33 MW rated turbines operating on an oversized circulating fluidized bed boiler with 120 MW capacity. The first area examined was reduction of auxiliary power consumption possible with the addition of variable frequency drives to the forced draft fan and booster fan motors. Included in this examination was an analysis of the economic and environmental impact of such a reduction. From the analysis an annual savings of 24.4 GWh of electricity is possible. The second area examined was the generation capacity lost due to condenser fouling and the possible reduction in facility emissions with altered condenser treatment. From the analysis an additional 3.0 MW of capacity facility wide is possible or a reduction steam production of 1.5% for each boiler.

Este trabalho tem como objetivo gerar subsídios para futuros estudos que busquem desenvolver carenagens de miniveículos com eficiência energética. Para tanto, são realizados estudos de diversas técnicas que podem influenciar no melhor desempenho com redução de consumo considerando menor perda de energia no ciclo de vida do produto usando os princípios da Ecologia. A partir da fundamentação teórica, foi desenvolvida uma carenagem aplicando a metodologia de Biônica baseada na forma do Límulus que é o ser vivo mais antigo do planeta. Foram utilizados recursos de tecnologia computacional para captura de seu formato, e utilização de softwares paramétricas para realização de análises de elementos finitos testando a eficiência de sua forma. Posteriormente foi proposto um desenho com uso de acessórios aerodinâmicos para verificação de seus comportamentos, que atendeu aos requisitos do projeto, adequando às questões de ergonomia e legislação nacional de trânsito. Por fim, foi construído um protótipo em escala real para realização de testes práticos e demonstração de técnicas para sua execução. Os resultados obtidos servirão de referência como método de desenvolvimento para novos miniveículos que se propõem a ter eficiência energética. / This study aims to generate subsidies for future research about the development of car body for mini vehicle with energy efficiency. For such purpose, diverse techniques that may influence on better performance with consumption reduction were studied, considering lower loss of energy during the life cycle of the product using the principies of Ecology. Based on academic background, a car body was developed applying Bionics methodology, more specifically the shape of Limulus, which is the oldest live being on the planet. Resources from computational technology were used to capture its format, as well as parametric software for finite element analysis testing the efficiency of its shape. Subsequently a design was proposed using aerodynamics accessories to verify its behavior, which met the requirements of the project, adapting to ergonomic issues and national traffic legislation. Lastly, a prototype was built in real scale for implementation of practical tests and technique demonstration. The results obtained can be used as a reference of development method for new mini vehicles with the purpose of having energy efficiency.

Doctor of Philosophy / Department of Electrical and Computer Engineering / Balasubramaniam Natarajan / The number of wireless devices is predicted to skyrocket from about 5 billion in 2015 to 25 billion by 2020. Therefore, traffic volume demand is envisioned to explode in the very near future. The proposed fifth generation (5G) of mobile networks is expected to be a mixture of network components with different sizes, transmit powers, back-haul connections and radio access technologies. While there are many interesting problems within the 5G framework, we address the challenges of energy-related management in a heterogeneous 5G networks. Based on the 5G architecture, in this dissertation, we present some fundamental methodologies to analyze and improve the energy efficiency of 5G network components using mathematical tools from optimization, control theory and stochastic geometry. Specifically, the main contributions of this research include: • We design power-saving modes in small cells to maximize energy efficiency. We first derive performance metrics for heterogeneous cellular networks with sleep modes based on stochastic geometry. Then we quantify the energy efficiency and maximize it with quality-of-service constraint based on an analytical model. We also develop a simple sleep strategy to further improve the energy efficiency according to traffic conditions. • We conduct a techno-economic analysis of heterogeneous cellular networks powered by both on-grid electricity and renewable energy. We propose a scheme to minimize the electricity cost based on a real-time pricing model. • We provide a framework to uncover desirable system design parameters that offer the best gains in terms of ergodic capacity and average achievable throughput for device-to-device underlay cellular networks. We also suggest a two-phase scheme to optimize the ergodic capacity while minimizing the total power consumption. • We investigate the modeling and analysis of simultaneous information and energy transfer in Internet of things and evaluate both transmission outage probability and power outage probability. Then we try to balance the trade-off between the outage performances by careful design of the power splitting ratio. This research provides valuable insights related to the trade-offs between energy-conservation and system performance in 5G networks. Theoretical and simulation results help verify the performance of the proposed algorithms.