Supermarket refrigeration systems are large emitters of high GWP refrigerants, and due to the Montreal protocol and F-gas regulation, which aim to phase out high GWP refrigerants, refrigeration systems with alternative refrigerants must be implemented in order to secure climate friendly and efficient refrigeration. One increasingly more popular alternative is transcritical refrigeration systems using only CO2 as a refrigerant. The aim of this master thesis was to investigate one of these transcritical CO2-systems in order to determine how cooling capacity, power and efficiency varies over a year and what the variations depend on. Another aim was to try to compare the transcritical CO2-system with the two refrigeration systems used earlier in the same supermarket. Simulations based on dimensional data from the manufacturers were executed for the three different systems, and the transcritical CO2-system was simulated over one year, using monthly averages of parameter data. Field measurements of power were also performed in order to determine how simulations and reality corresponded. The simulations with dimensional data indicated that the transcritical system had the best system performance in all categories investigated, although the results depend on the amount of transcritical operation during the year. The transcritical system generally demonstrates better results in the winter, due to a lower ambient temperature, which has a positive effect on parameters crucial to the efficiency of the system, such as condensing pressure and temperature and evaporating temperatures. One advantage of transcritical systems is the possibility to recover heat, but the heat recovery system in the supermarket was non-functioning during the project. It has however been estimated that considerable monetary savings can be obtained with functional heat recovery compared to purchased district heating that is currently used for space and water heating.

The electrical load, sampled every hour, at Salagatan 18 in Uppsala was used to form models and for forecasting the load. It was investigated whether Multi Seasonal ARIMA models and Support Vector Regression were suitable. The models were compared to a naive persistence benchmark in periods of high and low volatility. Both short range 24h and long range 168h forecasts were made. It was concluded that both model proposals could be used to forecast the electrical load series. ARIMA and Support Vector Regression model proposals outperformed the benchmark for long and short range forecasts in both volatile and non volatile settings. The mean absolute percentage errors of the best ARIMA model for a one week forecast were 15.1% and 21.6% for non volatile and volatile settings, respectively.

Forecasts show a rapidly increasing amount of electric vehicles in Sweden. The purpose of this study was to examine the challenges with a large scale expansion of charging infrastructure for electric vehicles (EV) in Sweden. This was partially achieved by a survey, which was sent to the majority of the electricity distribution network operators (EDNO) and some other companies associated with the charging infrastructure in Sweden. The other part of the study examined how an increasing amount of electric vehicles, according to forecasts from year 2019-2030, in a smaller society would affect the local power grid and the local transformer. The result from the survey showed that many EDNO had a lack of knowledge about home charging which could delay or obstruct the transition to electrified transports. Also, regulations for EV charging were somewhat unclear or non-existent and almost no EDNO are planning for flexibility resources year 2030. The case study for the small society showed that the increasing amount of EV to 2030 will very much affect the total power load which puts new demands on the EDNO regarding dimensioning and control/digitalisation of the infrastructure. To succeed with the implementation of a large scale expansion of EV charge infrastructure in Sweden, the communication between different companies within the business field is of great importance. ISSN:

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On behalf of the Swedish marine authority this report has been carried out with the purpose of partly making an energy survey on existing lightning devices, but also creating a user-friendly calculation program. 600 pcs. of light devices (light bouys and light dots), that all use alkaline unchargeable batteries, was used in the energy survey. All devices are located around the Swedish fairways. The calculation program was created on the basis of specific terms regarding calculating light intensity, as today’s method is deficient and inconsistent.   As result a calculation program was developed which makes it possible for the user to calculate, with known input data, the specific capacity needed for a battery regarding the period of time in use. The same method used in the calculation program was also used in the energy survey. With reference to the survey a large part of the purchased battery capacity is not being used. Batteries worth around SEK 800,000 are annually purchased and the report shows that, with a marginal for change of 3 months, a total saving of SEK 300, 000 could be made annually.   As of today the amount of unchargeable battieris purchased are to high, which the figures above shows. In order to reduce the usage of batteries better planned routes, increased knowledge about energy and better tools for calculation is needed. This work has contributed to the increase of knowledge and a user-friendly calculation program. / På uppdrag av Sjöfartsverket har detta examensarbete genomförts med syfte att dels göra en energikartläggning på befintliga lysanordningar men även att skapa ett användarvänligt beräkningsprogram. Energikartläggningen gjordes på ungefär 600 st. lysanordningar (lysbojar och lysprickar) som alla använder alkaliska engångsbatterier och är placerade runt om i Sveriges farleder. Beräkningsprogrammet skapades utifrån särskilda bestämmelser vid beräkning av ljusintensitet då dagens metod är bristfällig och inkonsekvent.   Resultatet blev att ett beräkningsprogram togs fram som gör det möjlig för användaren att med känd indata kunna beräkna vilken kapacitet på batteriet som behövs under en önskad driftperiod. Samma metod som i beräkningsprogrammet användes även vid energikartläggning som resulterade i att en stor del av den inköpta batterikapaciteten inte kom till användning. Batterier för ungefär 800 tkr inhandlas årligen och beräkningarna visar att med en bytesmarginal på 3 månader finns det fortfarande möjlighet att spara ungefär 300 tkr som procentuellt blir lite drygt 37 %.   I dagsläget köps de in alldeles för många engångsbatterier då siffrorna visar ett uppenbart energisvin. Det som krävs för att minska användningen av batterier är bättre planerade rutter, utökad kunskap om energi och bättre beräkningsverktyg. I de stora hela har detta arbete bidragit till ökad kunskap och ett användarvänligt beräkningsverktyg.

It has long been known that the building sector has problems regarding the work of experience feedback. Since Peab Sverige AB in Umeå previously experienced that there has been an improvement potential in this field, they had a student carry out a study on the experience feedback within the company. This took place in 2018 and resulted in a number of proposals for measures. As Peab one year later still had the feeling that the work with experience feedback could be improved, a follow-up was made on this previously study.   The theory is based on previous studies and literature in the field. Peabs routines have been reviewed through their intranet, planket. This to compare how the work with experience feedback works in reality, through an interview study with employees in the production at Stage 4 Mariehöjd. Which is a project of a multi-family house.   Many studies describes problems, due to lack of experience feedback. However, these are seldom made concrete. This study resulted in a number of examples of problems that have a connection to poor experience feedback, such as misplaced floor wells, inadequate fall protection and insufficient waterproofing in bathrooms etcetera. The costs of two problems linked to poor experience feedback have been calculated.   The main problems Peab Sverige AB in Umeå had regarding the work with experience feedback in production have proved to be lack of routines in the management of protocols from meetings that intend to treat experiences feedback. Obstacles that counteract the work with experience feedback have been identified. For example, employees must apply for authorization for certain documents. This study identified which of the previous action proposals were incorporated and resulted in new proposals based on those already given and new data. With help of earlier mentioned calculation, the cost of poor experience management could be presented.