Energy efficiency of buildings is an important measure to obtain a reduction of emissions of greenhouse gases since the building sector currently emits 40% of the total emissions in the world. A modification of control systems within commercial buildings is shown in earlier research to have a possible energy saving. The conventional control is usually controlled by fixed schedules and might presumably result in unnecessary energy use, since it operates at full capacity during the set period. Thus, modification of such control systems in commercial buildings might have a significant energy efficiency potential. The aim was to investigate the overlooked effect of human behavior on buildings’ energy usage. The hypothesis was a significant energy saving could be achieved if control systems use occupancy-based (OB) control instead of a conventional control based on fixed schedules. Firstly, occupancy data acquired from motion sensors in offices in the natural science building at Umeå University was used to create average occupancy patterns. The occupancy patterns were used to create various schedules with different objectives while representing the average floor occupancy. Secondly, the created schedules were used in the building simulation program IDA ICE. The simulation program was used to investigate how the energy consumption changed if the control system was changed to operate as OB control. Lastly, the potential energy savings were calculated with values from the simulations. The results showed that an average energy saving of 14% was achievable if OB control was used instead of fixed-schedule control. It was also found that a potential energy saving largely depends on the behavior of the occupants. Depending on the occupancy pattern and intensity, a potential energy saving of 10% to 17% was obtained. The results also signify the importance of well-functioning sensors and accurate detection. Additionally, it was found that the summer months had less potential energy savings compared to the other months. The results show that human behavior can have a large effect on the energy consumption within a building. Thus, implementing occupancy information in control systems might yield a potential energy saving. The intensity of occupants’ affects the potential energy saving. It was found that a higher intensity yields a lower potential while a lower intensity yields a larger potential energy saving. An interesting theory regarding the sensors was found after studying the results. It was found that it might be possible to let six arbitrarily offices represent 40 offices in an office environment. An important measure when collecting personal occupancy information is to inform the occupants of the experiment, as to not have problems with perceived privacy. Including the occupants in the data-collecting project might yield a better understanding and thus better collaboration with the experiment.

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Machine-to-Machine Communication (M2M) is the communications between wireless devices without human interventions. As a fundamental enabler of Internet of Things, M2M is growing fast and implemented in many areas. The number of M2M devices is expected to be extremely large in the future. In most cases they are battery driven and positioned in broad areas so that it would be costly to frequently replace or charge their batteries. To save the cost of maintaining M2M systems in the long term, energy consumption needs to be minimized so that battery lives of M2M devices can be maximized, which motivates the design of a lowpower MAC protocol in this thesis. The related works have indicated that idle listening and collisions are the main sources of power waste. In the proposed low-power MAC protocol design, various methods that would help preserving energy are considered. We first analyze the performance of three conventional protocols, TDMA, CSMA, and reservation-based protocol. The packet delay, energy consumption, and system throughput performances of these protocols are evaluated with both theoretical analysis and numerical simulations. Our results show that CSMA has better packet delay and throughput performances while static and dynamic TDMAs are more energy efficient. Furthermore, we design a hybrid energy-efficient MAC protocol for M2M communications. This solution not only improves existing protocols, but also takes the advantage of clustering in cellular networks to save energy. We show by simulation results that the proposed MAC protocol outperforms others in energy saving, without sacrificing much on delay or throughput. This is because with clustering, transmission power of remote nodes can be greatly reduced after they become members of clusters. With the proposed MAC protocol, the lifetimes of both individual nodes and the whole M2M network are significantly extended.

As the environmental impacts of the energy usage of the world today becomes more and more evident, enhancement of energy performance of the already existing building stock becomes more urgent. Buildings belonging to the cultural heritage are often the ones that are most difficult to deal with in this context. The subject of this thesis is the use of building simulation of historic buildings. The task here is to identify and when necessary develop simulation tools and methods that are suitable for planning of retrofitting strategies in historic buildings, and to identify and analyze what demands such tools and methods would have to fulfill, in what contexts different simulation strategies are suitable, how the demands on the tools might be met and what results and how the results would facilitate the decision making process in the most optimal way. A powerful means to acquire such analyses is the use of whole-building simulation. In the case of historical buildings there are several aspects to take into consideration, determining the choice of simulation tool and method. This thesis includes Investigation of the variability of the demands on simulation tools and methods that the historic buildings pose, and its implication on complexity of the simulation process, and suggestion of a complexity index tool. Investigation of the whole-building simulation process and how it complies with the demands identified, and how the exergy concept can be used, exemplified by a case study. Identification of a need for a tool and method for a large amount of cases not easily covered by abundantly available tools and methods Suggestion of a tool and method to address these cases, and presentation of a case study where the suggested tool and method have been applied, with good agreement between the simulated and measured values. One important feature of the suggested tool is the Very Small Wall-part Method, that includes the assessment of especially damage prone points into the whole-building simulation model, otherwise unable to accommodate these points. Another is the damage risk assessment feature where a mould risk prediction tool is presented. / <p>QC20120920</p>

Wireless access networks today consume 0.5 percent of the global energy. Rapidly growing demand for capacity will further increase the energy consumption. Thus, improving energy efficiency has a great importance not only for environmental awareness but also to lower the operational cost of network operators. However, current networks which are optimized based on non-energy related objectives introduce challenges towards green wireless access networks. In this thesis we investigate the solutions at the deployment level and handle energy efficiency assessment issues in wireless access networks. The precise characterization of the power consumption of the whole network has a crucial importance in order to obtain consistent conclusions from any proposed solution at the network level. For this purpose, we propose a novel power consumption model  considering  the impact of backhaul for two established technologies, i.e., fiber and microwave, which is often ignored in the literature. We show that there is a tradeoff between the power saved by using low power base stations and the excess power that has to be spent for backhauling their traffic which therefore needs to carefully be included into energy efficiency analysis. Furthermore, among the solutions that are analyzed, fiber-based backhaul solution is identified to outperform microwave regardless of the considered topology. The proposed model is then used to gain a general insight regarding the important design parameters and their possible impact on energy- and cost oriented network design. To this end, we present a  high-level framework to see the main tradeoffs between energy, infrastructure cost, spectrum and show that future high-capacity systems are increasingly limited by infrastructure and energy costs where spectrum has a strong positive impact on both. We then investigate different network deployment strategies to improve the energy efficiency where we focus on the impact of various base station types, cell size, power consumption parameters and the capacity demand. We propose a refined power consumption model where the parameters are determined in accordance with cell size. We show that network densification can only be justified when capacity expansion is anticipated and over-provisioning of the network is not plausible for greener network. The improvement through heterogeneous networks is indicated to be highly related to the traffic demand where up to 30% improvement is feasible for high area throughput targets. Furthermore, we consider the problem of energy efficiency assessment at the network level in order to allow operators to know their current status and quantify the potential energy savings of different solutions to establish future strategies. We propose elaborate metric forms that can characterize the efficiency and a methodology that indicate how to perform a reliable and accurate measurement considering the complexity of wireless networks. We show the weakness of the current metrics reporting the "effectiveness" and how these might indicate disputable improvement directions unless they are properly revised. This illustrates the need for a standardized network level energy efficiency evaluation methodology towards green wireless access. / <p>QC 20121109</p> / Energy-efficient wireless networking (eWIN)

In order to answer modern challenges, which come from increasing needs in energy forprivate persons and industries as well as in order to decrease negative environmentalimpacts, caused by the processes of energy generation, it is important to constantly searchfor untapped energy efficiency potential. Moreover, nowadays, energy efficiency hasbecome one of the prerequisites of successful market competitiveness for any type ofindustry on local and global levels.An energy audit is an instrument, which can be used for understanding how the energy isused and identify possible energy-saving opportunities. It can be applied to a facility as awhole, as well as individually to equipment, system(s) or process(es). Moreover, energysaving measures can be both cross-cutting and sector-specific.The purpose of this project was to conduct a detailed energy audit of the Hagby wasterecycling plant and to identify beneficial energy saving opportunities from economic,environmental and social perspectives.In the frames of a preliminary energy audit 10 focus areas for further analysis wereidentified. For every area a baseline assessment of the current energy performance wasconducted, possible energy management opportunities were identified and evaluated aswell as results of each analysis were summarized. According to the results of the study, with the implementation of the suggestions, whichrequire no, low or medium investments it is possible to save 3,2% of the energy per year,which corresponds to 76 846 kWh. Energy consumption can further be decreased byimplementing measures, which need high initial financial investment. In that case totalsavings will be 468 846 kWh or 19,4% of total annual energy consumption. Additionalenergy might be saved just by introducing energy housekeeping measures. Finally,implementation of all the proposed EMO can bring 14,46 tons of 2 CO savings annually.Additional benefits of implementing the energy saving opportunities come from decreasingenvironmental impacts, improving working conditions of the plant employees and higherenergy security at the plant.The results of the energy audit can be a solid base for establishing an energy managementprogram at the plant, which will include performance targets, required resources and aclear procedure of realization of improvements. However, since some of the calculations inthe current study are based on various assumptions, after the company forms the energymanagement program, it is necessary to invite experts from industry in order to giveaccurate calculations for each of the focus areas.

Cellular network based Machine-to-Machine (M2M) communications have been growing rapidly in recent years, being used in a wide range of services such as security, metering, health, remote control, tracking and so on. A critical issue that needs to be considered in M2M communications is the energy efficiency, typically the machines are powered by batteries of low capacity and it is important to optimize the way the power is consumed. In search of better M2M systems, we propose a context-aware framework for M2M communications so the machine type communication (MTC) devices dynamically adapt their settings depending on a series of characteristics such as data reporting mode and quality of service (QoS) features so higher energy efficient is achieved, extending the operating lifetime of the M2M network. Simulations were performed with four commonly used M2M applications:home security, telehealth, climate and smart metering, achieving considerable energy savings and operating lifetime extension on the network. Thus, it is shown that contexts play an important role on the energy efficiency of a M2M system.

The thesis begins with a discussion of the concept of sustainability, green buildings and the traditional valuation approach. Then valuable information are extracted from the reports of IMMOVALUE project, which is aiming to improve the market impact of energy certification by introducing energy efficiency and life cycle cost into property valuation practice. A survey collecting Swedish valuers‟ opinion towards the sustainability issue is implemented and some results from early surveys are also employed for exploring this research area.Energy efficiency/Energy Performance Certificate (EPC) is a breakpoint for the integration of green issues into property valuation practice. This is the most feasible way to quantify the effects of green features into property. Some modified methodologies based on the three traditional valuation approaches are proposed and the income related approach is the most suitable one here. For a good market acceptance of green buildings, the valuation of green issues must be taken.At the very early stage of the process of integrating green features into property valuation, this thesis explores the result from IMMOVALUE project and other researches. A close review of the process has been made and this may give valuers guidance of how to take green features into account not only in a qualitative, but also in a quantitative way.

The reduction of energy demand and increased energy efficiency is believed to play a major role in tackling the global climate change. Artificial lighting systems in commercial buildings accounts for a substantial proportion of the total energy consumption. Studies shows that significant energy savings can be achieved by improving the energy efficiency with the application of control systems and daylight sensors. However, this may not come to the expense of impaired visual comfort. This study contains a comparative analysis of methods to improve the visual comfort, optimise light sensor placement for proper performance and estimate the potential energy savings for a classroom located in Umeå, Sweden. The term visual comfort and corresponding photometric properties has been evaluated in regards to international standards and recommendations. The lumen method, a lighting design technique, showed promising accuracy in determining a more optimal lighting design, this was confirmed by using the lighting simulation software Dialux evo. The results obtained by the simulation software showed improved visual comfort in terms of illuminance-based metrics that fulfilled the international requirements EN12464-1.  A sensor positioning method denoted as "Point-by-point" has been evaluated for two different lighting designs. The current lighting design is based on the existing lighting arrangement in the classroom, denoted as "current design". The other lighting design is based on improved positioning attained by the lumen method, denoted "Test design 2". The point-by-point method showed considerate accuracy in comparison to reference values obtained by simulations, however the credibility of the method is dependent on the lighting design. The average deviation for the current design were determined to be 23.7 lx (15.16 \%), whilst the improved Test design 2 attained an lower average deviation of 8.3 lx (9.20 \%). Lighting characteristics of the luminaries also has an impact on the credibility of this method, as uniform lighting proves to be more suitable than non-uniform lighting.  The integration of daylight data in the simulations showed different optimal position for light sensors due to the natural changes in illuminance. Thus, the positions with the most established linear relationships between the light levels on the workplane and ceiling throughout the year were consider to be the most suitable. The point-by-point method for Test design 2 acquired an average deviation of 13.1 lx (16.40 \%) in comparison to the daylight simulations. The results showcased that this method may be applied in similar studies in the future. The daylight simulations indicated significant energy savings throughout the lifetime of the lamp. The most substantial savings were obtained in the month of May during the first year (63.4 \%). This study demonstrates that daylight harvesting is beneficial despite the latitude of the location with proper dimensioning of the fluorescent lighting system.

<p>Current global efforts in building information research include the development of low-cost, high reliability sensing systems capable of quantifying metrics such as human occupancy, indoor environmental quality, and building system dynamics. Such information is of high value for model development, building energy management, and improving occupant comfort. Further, indoor air quality (IAQ) has been a growing concern in recent years, only to be exacerbated by the COVID-19 pandemic. A common provisional measure for IAQ is carbon dioxide (CO2), which is regularly used to inform the ventilation control of buildings. However, few commercially available sensors exist that can reliably measure CO2 while being low cost, exhibiting low power consumption, and being easily deployable for use in applications such as occupancy monitoring. </p> <p><br></p> <p>This work presents research related to the initial development and evaluation of low-cost, stable, and easily deployable sensors for monitoring indoor CO2 levels in buildings. Two different types of sensors are presented that have the potential to perform as well as current commercially available CO2 sensing technologies, at significantly lower costs. The first is a chemiresistive sensor that is fabricated using a carbon nanotube thin film in conjunction with a blend of branched poly(ethylenimine) (PEI) and poly(ethylene glycol) (PEG), which serve as a CO2 absorbing layer. The second is a resonant mass sensor, functionalized with similar polymer-based materials including a blend of PEI and poly(ethylene oxide) (PEO). Prototype sensors were assessed in a bench-top environmental test chamber which varied temperatures, relative humidity levels, CO2 concentrations, as well as other gas constituents to simulate typical and extreme indoor conditions. The results indicate that the proposed system could ultimately serve as an attractive alternative to commercial CO2 sensors that are currently available.</p>