The thermal response of a borehole field is often described by non?dimensional response factors called gfunctions.The g?function was firstly generated as a numerical solution based on SBM (Superposition BoreholeModel). An analytical approach, the FLS (Finite Line Source), is also accepted for generating the g?function. In thiswork the potential to numerically produce g?functions is studied for circular borehole fields using the commercialsoftware COMSOL.

The energy consumption continues to increase as the use of electronics and energy consuming equipment increases. The use of fossil fuels has to be phased out for this to be sustainable in the long run while the use of renewable energy continues to increase. A renewable energy source is solar energy but the production of heat and electricity are today very expensive compared to other energy sources and an important task for the solar energy market to grow is therefore to minimize the production cost of the solar collectors while increasing its efficiency to produce heat and/or electricity. One way to convert solar energy into heat is by using solar collectors and electricity can be produced by utilizing the produced heat, or by applying solar cells.This thesis aims to recommend a reflective material for the next generation solar collectors from Absolicon and to recommend a commercially available coating for the receiver tube of the solar collector. A market study has been carried out to investigate the cost-related aspects along with the optical and durable aspects for the optical material of the solar collector.

The project was performed at SiemensIndustry Drive Technologies with theobjective to provide actual values forthe energy savings potential withinSiemens scope of practice.In Sweden the electrical drives standfor about 30 % of the total electricityconsumption and about 60 % of theelectricity consumption within theindustry. During the pre-study phaseelectrical drives with pump applicationswere identified as large energy users.Because of this a case study at one ofSiemens customers, Stora Enso Fors wasperformed. The system that was evaluatedduring the case study was a throttledsystem with a centrifugal pump forpumping pulp.The results yielded that a saving ofover 50 % could be achieved by replacingthe throttle valve with a variable speeddrive, a frequency converter. Thepayback period was two years and twomonths and the present value for thetotal life cycle cost of the variablespeed system was 662.566 SEK lower thanfor the throttled system. As aconsequence, Stora Enso Fors is advisedto invest in a frequency converter forregulation of the system.The general conclusion is that a focuson system efficiency is the mostimportant factor in energy efficiencyprojects and that the system regulationmethod has a large impact on the overallsystem losses and hence its efficiency.Energy efficiency potential forthrottled systems with centrifugal pumpsis large and significant economicalsavings can be made through investmentswith short payback time..

AbstractThe real estate sector is today responsible for 40 per cent of the total amount of energy consumption within the members of the EU. All over the world there are collaborations within research and projects to find ways of reducing the amount of energy consumed by the real estate sector. In Sweden, a directive from the European Union has posed demands on authorities as well as on the private sector to reduce the amount of energy consumed by new building constructions. Together with the directive from the EU there are also new requirements and demands from Boverket for the real estate sector.  These requirements mostly concern the energy consumption of kilowatt-hour per square metre and that the consumed energy also should be renewable.  The aim of this study is to explain what kind of value municipalities experience in using certifications and environmental investments for new and existing buildings. Within the chapter theory, essential areas are described such as; environmental certification systems, economical viability, proceeds connected to building green, difficulties with building green, the performance of green buildings when affected by the behaviour of tenants and customer value.  The following chapter describes the methodology with which we have conducted this study.

A power system will inevitably be subjected to transient overvoltages, most often produced by switching operations and lightning strikes. These transient overvoltages may harm sensitive equipment without sufficient protection, but it is not an easy task to predict what transients may occur or how they affect the system. A fault occurred in a low voltage system at Forsmark 2012 and overvoltages from lightning were concluded as the probable cause. The three aims with this thesis are to develop and test a model of the power system at Forsmark 3, analyse the transient behaviour of the system when subjected to lightning surges and identify critical parameters, and lastly to provide a tool for investigating the protection of the system. The modelling and simulations were performed in the freely available simulation program LT Spice.

All around the world more and more people move from rural areas to live in the cities. Because of this, the urban areas have become an important part in the debate about the effects on the environment and sustainability. In many countries word wide initiatives have been taken to build sustainable cities and eco cities, the Stockholm Royal Seaport is one example. The vision for the district is to become a world class sustainable city based on the three dimensions of sustainable development: social, economic and ecologic. The municipality of Stockholm has set requirements for the buildings? energy usage, emissions and amount of waste generated during the building process.

The interest in tiny wireless applications raises the demand for an integrated reference oscillator with the same performance as the macroscopic quartz crystal reference oscillators. The main challenge of the thesis is to prove that it is possible to build a MEMS based oscillator that approaches the accuracy level of existing quartz crystal oscillators. The MEMS resonator samples which Philips provides are measured and an equivalent electrical model is designed for them. This model is used in the simulations of the Pierce oscillator and the transresistance amplifier oscillator that are evaluated in this thesis. Finally the Pierce oscillator is implemented in the A BCD2 process and manufactured at Philips Semiconductors in Nijmegen, The Netherlands.

With a larger awareness of the climate changes and increasing electricity prices, energy efficiency measures in the industry have become more common. By rationalize the activity and by the same time decrease the emission of greenhouse gases the company can both save money and reduce negative environmental impact. For the Swedish industries the electricity price have traditional been relative low, which has resulted in a considerable larger usage than other European countries. By a deregulation of the European electricity market the electricity price will level off between the countries, which will cause a higher electricity price in Sweden than we are use to. To prevent that the Swedish industry don?t lose competitiveness against the other European countries, it will require energy efficiency activities in all different forms.ABB Sweden has decided to decrease their total energy usage with five percent in two years.

When several production units provide a district heating network, water is pumped from different directions. When the flows from the plants finally meet in the network, the water can be completely still. These places are called zero flow zones. In district heating networks with several plants, which also have different supply temperatures, large and frequent temperature fluctuations can occur when the zero flow zones move. This may cause wear on the pipes, a phenomenon called low cycle fatigue.For this reason it is important to examine where and when zero flow zones that cause temperature changes occur.

Along with rising energy prices and increasing awareness of environmental issues, the criteria for buildings energy performance have been sharpened through the years. Today, ?passive house? and ?low energy house? are commonly used phrases in the construction industry and is expected to become increasingly common in the future.For houses with well-insulated building envelope the importance of well constructed details increases when minimizing the heat losses. Examples of these details are floor-wall junction and window openings in the wall. In such connections thermal bridges occur, which means that heat more easily is transported out of the building, compared to the rest of the building envelope.This report deals with detail solutions around windows and a comparison between a traditional slab and a foundation from Koljern consisting of foam glass.

During the nineties, ecological handling of urban storm water became very popular in Sweden. Together with Chalmers University of Technology and two Swedish communities, DHI Water and Environment has been doing research of storm water ponds and constructed wetlands. This thesis work is a part of that research project. The work has been applied at the Bäckaslöv storm water treatment plant in Växjö, Sweden. The plant consists of one storm water pond and a downstream constructed wetland.

In today's society there is a significant focus on energy efficiency. Despite this, people leave lamps, televisions and computer screens etc. powered on unnecessarily. The goal of this project is to build a simple prototype for home automation where a user, via an application on a mobile phone, can switch on and off the power of an electrical products in the home and as well as being able to check whether such products are switched on or off. The prototype will also collect data on power consumption for these electrical products.

The demand for environmental assessments on buildings and energy consumption is increasing as well as the energy performance requirements for buildings. At the same time it is increasingly common with self-producers of heat and electricity generation.The main purpose with this master thesis is to investigate how time resolution affects the environmental assessment of energy consumption in office buildings connected to district heating (DH). Environmental assessments were done with both attributional LCA and consequential LCA with system expansion.Fortum´s DH system in Stockholm was analyzed and district heating production was simulated in a Matlab-model. Greenhouse gas (GHG) emissions for the production were calculated. The heat demand of the office Gångaren 16 in Stockholm was simulated in IDA ICE.

Cost allocation ? a study of how Swedish energy companies allocate costs between electricity and district heating in a combined heat and power plant District heating is today the most utilized alternative for heating in Sweden. In a combined heat and power plant (CHP) electricity and heat are cogenerated. The environmental and economic advantages with this kind of production are high. A problem in a CHP-plant is to allocate costs between electricity and heat since both products are generated in the same process.

This is a feasibility study that examines various aspects of building a wind farm on Malmön in Norrköping. The feasibility study deals with interests of conflict, park design, electrical connections, production calculation, financial calculations and operating- and timetable.The report is divided into two distinct parts. First a theoretical part, which deals with conflicting interests, park design and electrical connections. Second a part with simulations dealing with production calculations, and financial calculations.Opposing interests are mapped so that problem areas can be found, and help put focus on the right places at a future environmental impact assessment (EIA). There are a number of areas where planners have to assess on an EIA, this thesis point on the most important areas.