This thesis presents a system analysis for co-operation in local electricity markets including distributors and customers. The purpose of co-operation is to minimise the system cost of local markets by introducing system measures, such as end-use measures and municipal co-generation plants. Co-operation will strengthen the position of local markets in the national as well as future international electricity markets. With end-use measures local markets will achieve flexibility, additional reserve capacity and ability to avoid sudden large costs for peak loads. Biomass-fired cogeneration plants can become of great importance in an international market. In Sweden there is a simultaneous demand for electricity and district heating, many local markets already include district heating systems and there are major forest areas which can contribute with renewable fuel. The system analysis is partly based on the simulation model (INDSIM) and the linear programming model (MODEST). The simulation model has been further developed (STRATO) to include calculation of system costs. Shadow price analysis has been developed in order to study incentives for system measures. Calculation procedures have been developed that describe cooperation between distributor and customer. Six case studies of a selection of real, existing local markets in Sweden are presented. The studies show the potential economical effects of co-operation measured by system costs and shadow prices. Co-operation has been considered between demand- and supply-side, electricity- and district heating systems and also between different time periods. In a typical local market with 90 000 inhabitants, if end use measures are introduced without cooperation the system cost of the distributor will increase by 14 million SEK for a time period of 25 years. If instead end-use measures are introduced in co-operation, together with a biomass-fired cogeneration plant, the system cost of the local market will be reduced by 444 million SEK. Furthermore, the use of biomass in the local market is increased from 36 to 72 % while the use of oil is decreased from 34 to 1%. Another case study of another local market (50 000 inhabitants) shows that end-use measures will reduce the system cost (excluding investment costs) of an industry by 50 % corresponding to 1.3 million SEK for one year. The end-use measures imply reduced power demand during peak load periods in the local market and increased power demand during non- peak load periods.

In the Swedish electricity system there is a great potential for increasing the cost efficiency of the electricity use. However, today the economic incentives, offered for instance by existing electricity rates, are too weak to improve the use of the system. On the Swedish electricity market there are, at least, three different actors, the power producer, the distributor and the customer. Today these actors act separately due to low awareness of the costs for electricity generation, over the year and the day. If the actors are aware of the real electricity costs, cost-effective incentives will arise to introduce energy system measures that will reduce the energy system cost considerably. The thesis presents two energy system analyses of an existing Swedish municipality. The first analysis deals with the introduction of industrial end-use measures, with the local utility’s existing electricity rates as boundary conditions. The analysis is carried out with a simulation model for electricity use in industries. The second analysis deals with the introduction of energy system measures, on the municipal supply-side and demand-side, when the local electric utility and the customers are regarded as one system. The analysis is carried out with an optimization model, that is based on linear programming. The results show that if 17 industries introduce end-use measures, with the existing electricity rates as boundary conditions, their energy system costs will be reduced by 12 MSEK for a time period of 10 years, whereas the local utility will increase its energy system cost by 6 MSEK. However, if there is a co-operation between the local electric utility and the customers, their joint energy system cost will be reduced by 330 MSEK for a time period of 10 years.

Shadow prices for heat generation are used to study the impact of changes in heat demand on the total system cost of an existing district-heating system in Sweden. The energy system may be considered to be both dynamic, because there is energy storage, and time-dependent since the electricity tariff is time-differentiated and the heat demand varies over the year and day. The energy system has been analysed with and without energy storage. The analysis shows that despite a reduction in system cost, the use of energy storage can result in higher shadow prices for heat generation in some time periods.

In a national electricity system there often exists a great potential for increasing the cost-efficiency of the electricity use. However, if the economic incentives for improving the use of the system are too weak, it is most likely that this potential will not be utilised. If electricity tariffs reflect real electricity costs, over the year and the day, cost-effective incentives will arise for introducing energy system measures that will reduce the energy system cost considerably. This paper presents two energy system analyses of an existing Swedish municipal energy system. The analyses are carried out with a simulation model for electricity use in industrial energy systems, and an optimisation model that is based on linear programming.<>

In the Swedish electricity system there is a great potential for increasing the cost efficiency of electricity use. Today economic incentives, offered for instance by existing electricity tariffs, are too weak to improve the use of the system. On the Swedish electricity market, there are at least three different participants, the power producer, the distributor and the customer. Today these participants act separately owing to low awareness of the costs for electricity over the year and the day. If the participants are aware of the real electricity costs, cost-effective incentives for cooperation will arise. When participants cooperate, the introduction of end-use measures will reduce system costs for those participants that are involved in cooperation. We present a system analysis for cooperation between distributor and customers. We also present results from a project, where behaviours of an existing distributor and existing customers have been analysed. The results show that there exist cost-effective incentives for cooperation when end-use measures are introduced.

The hypothesis is that "a system optimisation model can be a powerful tool to produce basic data for strategic decision making in a local energy company". Another question is: do the companies trust the results? The model used is MODEST, which is a model for energy-system optimisation, built on linear programming. The local energy system in the municipality of Borlänge, has been analysed by means of MODEST and at the same time a traditional study has been carried out by an experienced energy-consultant. Both investigations were made under exactly the same conditions but totally independent of each other. Both studies came to same conclusions, and this was very important for the continued work.

A more extensive investigation was made when five communities, including Borlänge, joined to analyse the optimal energy supply in the region of Dalarna. The other communities are Hedemora, Säter, Avesta and Falun. By following the decision-making process in Borlänge and the other communities it has been possible to judge the usefulness of the MODEST mode! and the concept of energy system analyses that goes with it. The energy companies were interviewed about their experiences of the model. They all agree that they have confidence in the model, as the results correspond with their own calculations and knowledge of their energy systems. The process is easy to follow and the inputs to the model are data that always have to be processed in an investigation of a new investment or other changes of the energy supply. The result of the analysis is easy to comprehend.

Regarding Borlänge a decisive strategic decision has not yet been made. That depends on external insecurities on the energy market which are outside the modelling process. Not making a decision is also a strategic act. Based on the results of the analysis that have been made during the period of this work, 1997-1999, Borlänge Energy has decided to postpone the final decision for two or three years. The president of Borlänge Energy, Anders Lindberg, says that when it is time to make a strategic decision they will use the model again. The other energy companies also agree that their future decisions will be built on the results of the MODEST-analyses.

The conclusions of the thesis state that the system-analyses model MODEST calculates correctly and the concept of the analysing process is well adapted to a local energy system. The systematic way in which the analysing process is carried out stimulates the creativity and creates an active learning process among the participants. The results are trustworthy.

This is an analysis of the effect on the technical solution when monetary values of externalities are included in a model for optimising energy systems. The focus of the study is on heating in domestic houses, non-residential premises, multi-dwelling buildings and district heating systems. The included monetary values of damage to the environment and health are those resulting from atmospheric emissions Of CO2, NOx, SO2 and particulates. The estimates are taken from the literature. An optimising method based on linear programming is used and the result is an optimal mix of energy carriers as well as new and existing heating plants that minimise the costs of satisfying a demand for heat. Furthermore, a calculation is made of the externality cost resulting from the energy system. The analysis makes it possible to compare the technical and economic differences of an energy system based on business economics to a system with greater emphasis on socio-economics. Generally speaking, it is cost-effective to take externality costs into consideration at the planning stage instead of correcting the damage later. The results show that by considering externality costs the total discounted cost of the energy system would be approximately 30% lower than today. Furthermore, the use of pellets and wood chips should be substantially larger in all of the studied regions. (C) 2002 Elsevier Science Ltd. All rights reserved.

Global warming is one of the most important environmental issues today. One step for the European Union to fulfil the Kyoto protocol, stating a worldwide decrease of emissions of greenhouse gases, is to treat the environment as a scarce resource by attributing costs for environmental impact. This accompanied with considering the European electricity market as one common market, where coal condensing power is the marginal production, lead to the possibility to reduce CO2-emissions in Europe by reconstructing energy systems at a local scale in Sweden. A regional energy system model is used to study possibilities to replace electricity and fossil fuel used for heating with biomass and how a reconstruction can affect the emissions of CO2. An economic approach is used where cost-effective technical measures are analysed using present conditions and by including monetary values of externalities. The analysis shows that, by acting economically rational, a large amount of electricity and fossil fuel should, in three Out Of four cases, be replaced leading to a substantial reduction of CO2 emissions. (C) 2002 Elsevier Science Ltd. All rights reserved.

The production of heat and electricity can cause large environmental impacts and, hence, large costs for society. Those are costs that are seldom taken into consideration. An important question is how the future technical energy systems should be formed if environmental costs were considered as any other good or service, such as raw material, capital and labour. This study comprises cost-effective technical measures when monetary values of external effects are included in an energy system analysis. It is an analysis of how the present energy system can for society be cost-effectively reconstructed to be more sustainable. A regional energy system model has been developed to perform the study and it concentrates upon production of heat in single-family houses, multi-dwelling buildings, non-residential promises and district heating systems. The analysis adopts a business economic perspective, using present prices of energy carriers, and a more socio-economic perspective, in which external costs are included. The result of the analysis is the optimal mix of energy carriers as well as new and existing heating plants that minimizes the costs of satisfying a demand for heat. The results show that it is profitable to invest in new heating plants fuelled with woody biomass. Furthermore, the external costs arising with satisfying the demand for heat can decrease substantially, 60%, by carrying through with the investments that are cost-effective according to the institutional rules valid today. When monetary values of external costs are taken into consideration, this number is additional 5-percentage points lower. It is shown that if environmental costs are included it is more expensive to continue with business as usual than it is to reconstruct and run a more sustainable energy system.

Rapporten bygger på en fallstudie i Söderköpings kommu och sätter bilder av framtidens uppvärmningssystem och dessa bilders betydelser för lokalt förändringsarbete i fokus. I fallstudien ingår intervjuer med 4 kommunpolitiker, 4 kommunal tjänstemän samt 2 representater för det privata fjärrvärmeföretaget. Dessutom studeras kommunal protokoll samt massmedierapporteringen kring uppvärmningen i Söderköping. Centrala frågor är: Hur tolkar lokala aktörer tidigare förändringar?; Hur påverkar dessa tolkningar aktörernas bilder av framtidens uppvärmningssystem?; Vilka förhoppningar och farhågor knyts till framtiden?; samt Hur kan lokala framtidsbilder omformas till scenarier och hur kandessa scenarier användas i det kommande energiarbetet i kommunen? Rapportens bärande kategorier är historier, framtidsbilder och scenarier. Med historier menas de berättelser om tidigare förändringar som återfinns i massmedia och kommunala protokoll, men också i informanternas intervjuer. Framtidsbilder utgörs av de förhoppningar och farhågor kring den framtida utvecklingen av uppvärmningssystemet som förmedlats via intervjuerna. Med scenarier menas slutligen de renodlingar och utvecklingar av centrala drag i framtidsbilderna som forskarna stått för och som utvecklats till diskussionsunderlag för kommande energiarbete i kommunen. De scenarier som presenteras och diskuteras är: Centraliserade biobränslesystem Värmepumpskommunen, samt Den decentraliserade självhushållningen

Den situation som olika aktörer Söderköping står inför då det gäller uppvärmningssystemet fokuseras i den studie som presenteras. Huvudsyftet med arbetet har varit att studera aktörernas uppfattning om hur uppvärmningssystemet kan utvecklas samt vilka lokala scenarier som kan skapas. Studien belyser frågor som vilka hinder och möjligheter som finns för uppvärmningssystemets utveckling givet lokala förutsättningar samt hur olika aktörers inflytande skiftar i olika utvecklingsmöjligheter. Presentationen bygger på rapporten "Att förändra ett uppvärmningssystem: bilder av framtidens uppvärmningssystem i Söderköping"

The object of this inventory study was to study the effect on the indoor environment and allergy parameters after adequate measures were taken in damp-damaged one-family houses with HDM allergic occupants.

Moisture may cause damage on building material and increase allergic symptoms. If adequate measures considering moisture are taken in a damaged building this should improve the indoor air quality and thereby reduce the allergic symptoms in allergic patients.

In this study fifteen patients with allergy to house dust mites (HDM) and living in houses with severe moisture problems were selected. Several technical parameters were measured before and after (one year or more) adequate taken measures. These parameters were e.g. ventilation rate, HDM-content in e.g. mattresses, temperature and moisture conditions in indoor air and in the damaged/damp building structures. In parallel to the technical measurements, questionnaire and medical parameters on each patients including HDM-specific IgE, ECP, symptom score and spirometry were followed.

The results show a significant reduction of moisture. Improved indoor air quality and odour condition were seen after adequate taken measures. Significant improvements in some clinical data and allergy laboratory tests were noticed. In conclusion this study shows that adequate taken measures in severe moisture damaged houses can improve indoor air quality, well being and may also reduce the conditions for continuing allergy problems in HDM allergic patients.

The objective of this cross-disciplinary project has been to find relationships between the indoor environment in the homes of 60 young asthmatics and their pattern of disease. The patients were selected by paediatric allergy specialists, who also made available the results of sensitisation tests and assessments of the severity of the patient's asthma.

Field measurements were made in 60 homes during the winter of 1990/91, covering moisture, temperature, ventilation, volatile organic compounds (VOC), formaldehyde, carbon dioxide, radon and particles. In addition bacteria, endotoxins and microfungi in dust were also measured, and information was obtained concerning the families' lifestyle and their houses.

The results show that ventilation air change rates per person were only about half of the aver­ age value for Swedish housing stock. Low ventilation tended to be linked to higher levels of various pollutants.

The results, based on about 160 different parameters, do not show any simple relationship between the parameters which tend to describe the patients' condition in general terms and their indoor environment. What were revealed, however, were several interesting significant relationships between individual physical and medical parameters. Many of the results could be suitable as starting points for continued research, while others indicate ways in which the indoor environment could be improved in order to reduce the risk of development of allergies.

Traditionally, Swedish industries have been experiencing lower power prices compared with industries in the European continent. The specific power consumption is 2- 3 times higher than other competing industries abroad.

Since July 2004, the power market is deregulated where industries have the possibility to choose supplier. This could imply a harmonized price level across the continent. This would be disadvantageous for Swedish companies if nothing will be done to reduce power consumption.

Marginal power production is based on coal-fired condensing power plant in the European power system. Independent of location, reducing the use of electricity would affect the use of expensive and environmentally not favorable plants.

In this thesis a method that can be used by nearly all industries is presented. The method has been applied on different case studies within different projects like project in Volvo Cars plants in Guthenburg and Gent, Electrolux cooker manufacturing in three European cities, Fredericia in Denmark, Spennymoor in England, Motala in Sweden and in the Oskarshamn area and a similar project ELOST in Östergotland and within program "Uthållig kommun" in Sweden.

The studies show that the all industries that are considered can reduce their electricity energy use by about 50 %. This would imply significant reduction of carbon dioxide emission in the continent.

Using top-down approach system failures can be identified and corresponding measures can be taken to improve the system. The use of energy can be reduced through energy avoiding cooling and heating at the same time, controlled operation of compressors and the use of power driven tools instead of compressed air driven tools, the use of efficient lamps and controlled ventilation or totally avoiding ventilation in some manufacturing halls, application of district heating driven absorption chillers and no production use can also contribute to reduced electric energy use.

Experiences from performed case studies indicate that system failures regarding the electricity use have been detected in nearly all investigated industries.

Three "laws" are distinguished:

• 1kWh electricity from a coal fires condensing power plant will give rise to aout 1kg CO₂ i.i. : 1 kwh el ≈ 1 kg CO₂
• Low electricity price implicate high electricity use and vice versa i.e: (Electricity price) times (specific use) ≈ constant
• The efficiency of a coal fired condensing power plant is about 30% which implicate: Electricity price > three times the fuel price

A century after the introduction of the first district heating system (DHS) on a commercial basis, the technology has still not become as widespread as it deserves to be. The role of district heating (DH) has meant not only comfort for its users but also less impact on the environment. At a time when the negative impact on climate of using energy and the liberalisation of energy markets are prominent issues, efficient DHS which are competitive both at national and international levels are needed. DH could be introduced at additional locations and existing networks could expand in areas with detached houses and industries. Combined heat and power (CHP) production promotes the integration of the Swedish DH sector with the rest of Europe.

A step that enhances the benefit of DH is co-operation in DH systems at local and regional levels. The established DHS in many Swedish municipalities make this step easier to implement. Industries and DH utilities may collaborate around heat supply by looking beyond their traditional boundaries, thereby promoting an efficient use of energy.

This study enlightens the importance of co-operation in DH systems using several real-world cases. The impact of the introduction of external cost, the deregulated power market, investments and various policy instruments on the energy systems is considered. Some of the cases indicate clear advantages even under current conditions whilst others are dependent on the future boundary conditions assumed. In most cases CHP production is encouraged as a result of interconnection of DH and industrial energy systems. The results of this study may serve to encourage decision makers to think in terms of co-operation.

The modelling of the regional and industrial energy system was carried out using an improved version of the MODEST energy system optimisation tool. The improvement of the modelling environment of the tool has substantially facilitated the system analysis work.

It should be mentioned that though co-operation could lead to lower costs and more efficient use of energy, other factors such as the relationships between the actors, may hinder a collaboration project. Independent techno-econornical analyses like these may help create a forum for discussion for the parties involved where other aspects of co-operation could be discussed.

This study describes the impact of widened system boundaries in the choice of heat generating plants, the total cost of the defined energy system and the use of combined heat and power (CHP) production plants. The economic and environmental benefits of co­ operation between public utilities and industries and the importance of enlarged system boundaries are shown in the different case-studies.

The analysis was based on computer modelling of municipal and industrial energy systems. A user-friendly graphical interface program based on the linear programming model, MODEST, was developed as part of this study. The majority of the case-studies presented in this thesis were then performed with this application program.

The various case-studies clearly indicate the cost reduction potential of co-operation. Both utilities and heat supplying industries benefit from this co-operation concerning heat supply. The cost saving potentials change from one case to another and depend on several factors.

New plants within a sub-system appear to be attractive when this system is connected with other sub-systems within the extended system boundaries. In general, we can say that an extended system boundary leads normally to reduced total costs, more rational utilisation of plants, increased heat and electricity generation through the CHP plant and declining use of fossil fuels.

The net present value of the maximum allowable investment cost for district-heating pipeline connections is roughly estimated when the cost for connection is not given or known. This cost can be used as a guideline to indicate whether connections should be considered or not.

Regions with densely concentration of industries and district heating systems (DHS) could be interesting study object from the light of an integrated heat market on local basis. System analysis with a widened system boundary could be used as an approach to evaluate the benefit of an integrated heat supply system. In this study, an energy system model consisting of totally seven different participants is designed and the optimization results of the system analysis are presented. With applied data and assumptions, the study shows that a significant amount of the heat demand within two sub-systems can be covered by heat supply from the heat market (the entire heat comes from two industries). Shadow prices, which can be used for heat pricing, indicate the advantage of an integrated system. The system cost reduction through integration and the availability of several actors with diverse energy supply system, makes the region under study an interesting area to prove a locally deregulated heat market.

Different energy and exergy concepts and methods are presented and applied to a Swedish pulp and paper mill. Flow diagrams show that the exergy content is mostly much less than the energy content of the flows. The largest exergy losses appear in the boilers. Heating processes are highly exergy inefficient. A limited Life Cycle Exergy Analysis (LCEA) shows that the exergy output amounts to over 3 times the spent exergy as non-sustainable resources. By replacing the present use of non-sustainable resources, mostly fuel oil, the mill could move towards a truly sustainable process.

With finite natural resources and large energy demands in the world, a sustainable development approach becomes increasingly important in the improvement of energy systems. The concept of sustainability is examined with relation to exergy flows on the earth. The present industrial society is obviously not sustainable. The main aim of this study is to analyze and improve industrial energy systems towards an increased sustainability.

Exergy analysis is used for evaluating energy systems and for guiding efficiency-improvement efforts. An existing optimization method is improved and applied to an energy system in order to maximize its economic feasibility and profitability. Life cycle analysis based on exergy is applied in order to further guide towards sustainable development. This thesis offers tools to better evaluate energy systems with regard to physical resource use, economy and environment. These tools are particularly useful for decision-making in long-term plarming.

The concepts and methods presented are useful in the design and optimization of more sustainable energy systems, particularly in industrial processes. A typical Swedish industry, a pulp and board mill, is examined using an improved optimization method together with the exergy method. The main cause of the low exergy efficiency in the mill is irreversibility of combustion and of heat transfer in the steam generator. The change in the price of electricity has a greater effect on the energy cost than the change in the price of fuel, which means a unified European electricity market has large impact on the Swedish industry. Increasing efficiency of processes usually minimizes environmental damage and maximizes economic benefits. In spite of increasing the exergy loss switching from fossil fuel to bio-fuels can decrease the net CO₂ emission as well as the energy cost, and is a step towards increased sustainability. The investments in an oil-bark boiler, evaporation plant and recovery boiler give a good supply of sustainable resources, a reduction of environmental impact, and both energy and economical saving. In addition, with replacing the present evaporation plant with the non-conventional one, even more benefits could be achieved. Still, there are more potential for further improvement in the mill.

The MIND (Method for analysis of INDustrial energy systems) method has been developed for cost optimisation of industrial energy systems, mainly with regard to quantities of energy. Exergy analysis reveals losses, efficiencies and possible improvements. These methods can be combined in order to improve industrial energy systems. In this paper, a Swedish pulp and board mill is used as a case study. The efficiencies of the processes in the mill are evaluated using exergy analysis. The most exergy inefficient processes are indicated and some improvements are suggested. This case study shows that it is the boilers and the evaporation plant that are the most inefficient processes, with efficiencies down to 29%. Different investment alternatives for these processes are studied and cost optimisation is achieved using the MIND method. The study shows that the energy costs can be reduced by up to 15 million Euros per year while the exergy efficiency can be improved by up to 14%. The combined approach shows that the energy cost-efficient alternatives are also usually exergy efficient.

No abstract available.

This second part is the continuation of Wall and Gong [Exergy Internat. J. 1 (3) (2001), in press]. This part is an overview of a number of different methods based on concepts presented in the first part and applies these to real systems. A number of ecological indicators will be presented and the concept of sustainable development will be further clarified. The method of Life Cycle Exergy Analysis will be presented. Exergy will be applied to emissions into the environment by case studies in order to describe and evaluate its values and limitation as an ecological indicator. Exergy is concluded to be a suitable ecological indicator and future research in this area is strongly recommended.

Load management of electricity loads has received more interest in recent years. At least in Sweden, this is natural because of a rather cheap energy price, while at the same time, the demand charge is high. If a company could save the precise kWh that build the peak demand, then these would have a value of more than 200 times the off-peak kWh. This paper deals with monitored electricity data for two carpentry industries and one municipality, both situated in the south of Sweden. The ideal ! situation would be if the industry could reduce their peak demand and, at the same time, reduce the peak for the utility. Both participants would, in that case, save money, and the payback time for load management equipment would decrease substantially. If, however, a load management system at the carpentry transfers kWh to peak hours for the utility, the industry will save money, while the utility gets higher costs. The result of the study is that the Swedish electricity rates in use today are a very poor means of encouraging worthwhile load management, and often, they even aggravate the situation.

As a result of a National Referendum and a subsequent parliament decision Sweden will phase out its nuclear power stations before the year 2010. This source of electricity accounts for about half the total electricity usage and therefore other sources must be constructed, or the country must use less electricity. One way to accomplish this, according to economic theory, is to increase the price of electricity, and we will probably be subject to such actions, at least if there is a risk of a shortage of electricity. Hitherto, most interest for saving energy has been emphasised on space and domestic hot water heating in buildings. The major part of electricity, however, is used in industry, and is therefore worth studying in more detail. One small carpentry plant which manufactures wooden staircases and fibreboard panels for ceilings has been studied. Using monitored data for 1 year of their electricity usage and costs, the amount of money which could be saved by the owner of the factory, if different load management measures had been applied, has been calculated. Thus it was possible to find the maximum cost for equipment that can turn off some processes, such as timber dryers, for short periods.

When chairs and other furniture are designed the work is mostly founded on handicraft experience. Calculations based on solid mechanics theory are almost never used in order to find out optimal solutions for different wood members, or the structure as a whole. We have therefore studied a simple chair, made of birch, where the emphasis is laid on its ability to carry different loads. Using the method of finite elements we have predicted the strain and stress at different points on the chair structure. Further, we have manufactured the chair and exposed it to the same load pattern as used in the finite element calculations. The strain has been monitored and compared to the calculated value at the points of most interest. The result shows that part of the calculations corresponded fairly well with the monitored values but also that much work still remains in order to totally predict the accurate structural behaviour for such a simple frame as a chair. Probably, some of the discrepancies depend on the wood material which exhibits so different response for stress in different directions.

During recent years more interest has been emphasised on wood as a construction material. This is so because wood is a renewable resource and also because problems with waste do not emerge when the wooden structure is taken out of operation. On the contrary this waste is still a resource even if the structure is demolished. Wood could always be used as a biomass fuel which is not expected to contribute to the greenhouse effect. In Sweden most of the interest has been emphasised on our conifers while broad leaved species are much less examined. This paper shows the result from the Finite Element Method applied on indetermined chair frames and compares these findings with actual testing in our laboratory. The conclusion is that there are considerable discrepancies between calculations and real behaviour even for relatively simple structures such as a chair frame. It seems that the real chair is stronger than expected even if the joints between the furniture members must reduce the overall strength found by the FEM calculations.

Load management is one means of reducing maximum electricity load, and hence also the cost of electricity. In Sweden, the amount charged during the maximum load hour might be about 200 times higher than the standard charge for one kilowatt-hour. If the load could be reduced by certain equipment in factories and buildings, the need for new power stations and higher capacity in the grid would also be decreased. Using electricity load data for one full year and a short computer program, this paper shows by how much the load could be reduced by postponing demand. If part of the load could be postponed by only one hour, this part may need to be only very small for maximum benefit. If longer time segments were practicable, larger chunks could be transferred. The main result of the study is, however, that load management in practice is a very subtle task if an optimal solution is to be achieved

The wood manufacturing industry in Sweden is not very often the subject of academic research activities. In certain parts of Sweden, generally in rural areas, this industrial branch is of major importance as a local employer. If the companies could grow and prosper it would lead to a more vivid countryside and decrease migration to larger towns and cities. The council of the European Community has therefore introduced certain funds for research projects in such rural areas. This paper describes the use of electricity and heat in a carpentry factory. The result shows that energy conservation measures and load management might be of significant importance in order to make the company more profitable. Even small savings can be the difference between survival or bankruptcy. For the studied factory it is obvious that much equipment for heating purposes are in a poor state. The steam system which could be useful for decreasing the use of electricity heating suffers from leaking steam traps and other imperfections which lead to severe losses in both kilowatt-hours and money. The steam system is therefore not used in an optimal way

A large part of Sweden is located within the Taiga Area and hence most of the wood species growing there are included in the division of Coniferales. This has also led to major research activities on the needle-leaved types in the Pinaceae family. There are, however, many broad-leaved trees, but because of their relatively low economic importance only a few researchers have had the opportunity to study such woods. For certain branches of the Swedish wood manufacturing industry the Angiosperms are of vital importance, e.g. the furniture factories. In this paper the mechanical properties of two Swedish hard wood genera, namely Betula and Alnus, are revealed. These findings are also compared with those found in the literature.

When a building is subject for refurbishment it is important to add only such measures that will reduce the Life Cycle Cost (LCC), for the building. Even better is to add measures that will, not only reduce the cost, but minimise the LCC. One means for such an optimisation is to use the so called Linear Programming (LP), technique. One drawback with LP models is that they must be entirely linear and therefore two variables cannot be, for example, multiplied with each other. The costs for building retrofits are, however, not very often linear but instead ‘steps’ are present in their cost functions. This calamity can, at least to a part, be solved by introducing binary integers, i.e., variables that only can assume 2 values, 0 or 1. In this paper it is described how to design such a Mixed Integer Linear Programming (MILP), model of a building and how different cost elements of the climate shield influence the optimal solution.

Linear programming models used for optimisation of various energy systems have received increased interest during the last ten years. One reason for this is the use of personal computers. Models with thousands of variables and constraints can now be rapidly optimised. If integers are introduced, which are necessary when increments or steps in cost functions are part of the model, the computing power is of even higher interest. However, many scientific authors do not discuss in detail how the model is designed and what basic data lie behind this design. This paper presents an attempt to study municipal thermal and electricity loads, and further how to divide data for one year into useful segments for linear and mixed integer programming purposes

In Sweden, forest research has been emphasised on mainly two species of wood, i.e. pine and spruce. However, we have also a number of hardwoods which could be utilised for furniture manufacturing, cabinets etc. Nowadays, these hardwoods are a slumbering resource in our country. Most of our broad leafed species are found as small stands inside our soft wood forests and hence not utilised in the most profitable way. For example, much of our birch wood is ground to paper fibres even if it would be perfect for high valued veneer. Instead, most of our birch. veneer is imported from Finland. In order to increase the interest for Swedish hardwoods we therefore have started research in this field and have now designed a chair made of ash wood,Fraxinus excelsior. Most chairs are made up of structural elements called indetermined frames which makes it a rather tedious task to analyse the internal forces in the frame. However, by using the Finite Element Method, FEM, it has been possible to reduce this drawback. This paper shows how a chair could be analysed, and designed, by use of methods common in other disciplines than furniture manufacturing. We also present results, in the form of stress-strain diagrams, from tests made on Swedish ash.

When a building is refurbished, energy conservation measures might be profitable to implement. The profitability depends, among other things, on the electricity and district-heating tariffs, the unit price for oil, etc. The cost for the retrofit is of course also important as well as the influence of the retrofit on the demand for heat in the building. By the use of a Mixed Integer Linear Programming model of a building, a number of different optimal retrofit strategies are found depending on the energy cost. The result shows that the Life-Cycle Cost for the building is subject only to small changes as long as the optimal strategies are chosen. Most important is the heating system, while building retrofits such as added insulation, are too expensive to take part in the optimal solution.

Wood is an anisotropic material and, further, because of its natural origin the mechanical properties might significantly differ also between each of the samples tested. Ordinary methods for evaluation of solid mechanic properties often destroy the tested specimens. It is therefore not common practice to evaluate more than one property, e.g. Young's modulus for tension, at the same time using the same sample. Different tests also have different recommendations of how the test specimens should be designed in order to test the property of interest. When calculations are to be made by e.g. the Finite Element Method values for a number of properties must be included and when the resulting construction is examined after this, it is not easy to decide if discrepancies depend on unreliable input data. This paper therefore describes tension, compression and bending tests for one specific detail, namely a wood beam of ash wood. The applied forces are well under those where rupture occurs and hence the material is assumed to be intact during all testing procedures.

Chairs and other furniture are seldom designed by help of structural mechanics and modern computers. Even if the designer uses a sophisticated CAD program, he, or she, will not use for example, finite element programs, FEM, in order to optimise the construction. Most furniture is made of wood or wood composites. Usually, structural mechanics is used for designing wood members in roof constructions and so forth. Because of the consequences of a breakdown, the allowable design stresses must be very low, about one third of the measured breaking strength. Smaller wood details could be chosen with more care and for chairs the result of a break would not necessarily lead to a disaster. However, a lot of the knowledge about how to design small wood structures emanates from the pre-war aeroplane industry. The difference between tensile and compression strength properties in wood also makes ordinary FEM programs hazardous to use because the background theory assumes that these properties are equal in magnitude. In this paper we show how to calculate the internal stresses of an undetermined chair frame and also show some material test results for Swedish alder, Alnus glutinosa.

The optimal heating-system-retrofit strategy for existing buildings differs due to varying prices of energy, building and installation features, climate conditions, etc. We have examined a test building situated in Linköping, Sweden. By using the OPERA model, we were able to arrive at the optimal retrofit strategy, which includes a ground-coupled heat pump using electricity to run the compressor. Unfortunately, the price of electricity differs according to the time of day, month, etc. These variations are not included in the OPERA model. In OPERA, the price should be divided into 12 segments, one for each month of the year since climate data are divided in this manner. Fine tuning of a dual-fuel system (an oil-fired boiler handles the peak load and a heat pump the base thermal load) is optimized using the Mixed Integer Linear Programming (MILP) method. Adding a hot-water accumulator also makes it possible to use low electricity prices for space and domestic hot-water heating. This system competes in the model with traditional heating devices such as district heating. The optimal method of heating the building was found for using the heat pump alone.

Since the nineteen-seventies, electricity has become a common heating source in Swedish single-family houses. About one million smallhouses can use electricity for heating, about 600.000 have electricity as the only heating source.

A liberalised European electricity market would most likely raise the Swedish electricity prices during daytime on weekdays and lower it at other times. In the long run, electrical heating of houses would be replaced by fuels, but in the shorter perspective, other strategies may be considered. This report evaluates the use of electricity for heating a dwelling, or part of it, at night when both the demand and the price are low. The stored heat is utilised in the daytime some hours later, when the electricity price is high.

Essential for heat storage is the thermal time constant. The report gives a simple theoretical framework for the calculation of the time constant for a single-family house with furniture. Furthermore the “comfort” time constant, that is, the time for a house to cool down from a maximum to a minimum acceptable temperature, is derived. Two theoretical model houses are calculated, and the results are compared to data from empirical studies in three inhabited test houses.

The results show that it was possible to store about 8 kWh/K in a house from the seventies and about 5 kWh/K in a house from the eighties. The time constants were 34 h and 53 h, respectively. During winter conditions with 0°C outdoor, the “comfort” time constants with maximum and minimum indoor temperatures of 23 and 20°C were 6 h and 10 h.

The results indicate that the maximum load-shifting potential of an average single family house is about 1 kW during 16 daytime hours shifted into 2 kW during 8 night hours. Up-scaled to the one million Swedish single-family houses that can use electricity as a heating source, the maximum potential is 1000 MW daytime time-shifted into 2000 MW at night.

Energy may be supplied by a multitude of components. Computer simulation helps in finding a beneficial system design. The energy-system optimisation model MODEST has been developed, and it has been applied to municipal, regional, and national energy systems. The most favourable combinations of present and potential equipment and energy flows have been obtained.

MODEST uses linear programming to minimise capital and operation costs. A flexible time division can reflect demand peaks and diurnal, weekly, seasonal, and long-term variations of demand, costs, capacities, etc. The optimal kinds, sizes, and occasions for investments and the best system operation are found. MODEST has been used to study energy supply and demand-side measures in 40 municipalities, three provinces, and the Swedish electricity system.

The national power system was studied at the request of the governmental Energy Commission. A nuclear phase-out would cause a 30% cost increase for satisfying the useful energydemand that today is covered by electricity in Sweden. Cogeneration should replace some nuclear-power production, and power export would decrease. To achieve environmental sustainability, biofuel and wind power should complement hydroelectric power because naturalgas and condensing-power capacity expansion would enhance CO₂ emissions significantly. Increased electricity costs would make consumers introduce more fuel switching from electricity to oil or biomass for heating. Industrial energy conservation and load management have robust profitability irrespective of nuclear-power, fossil-fuel, and carbon-dioxide restrictions. Obtained marginal costs for electricity supply may reflect electricity prices in a deregulated market and can be used as input to local studies.

Many local electricity and district-heating utilities have assigned tasks where MODEST has been used as decision support. Introducing heat-only boilers and combined heat and power (CHP)plants can accomplish cost minimisation at low and high electricity prices, respectively. The use of oil, woodchips, etc. depends on taxes and environmental fees. A heat storage may cover demand peaks, increase the heat sink for CHP, and be charged by heat pumps that use cheap night electricity.

MODEST has, thus, been applied to many different energy systems, and the most suitable installations and operations have been found.