The global energy usage have been growing and is expected to grow in the forthcoming years. The negative effects of increased energy use are greatly depending on the type of base raw materials required for converting the energy and the negative consequences those have on the environment. From the energy used, fossil fuels stands for the largest part. Excess use of fossil fuels have been shown to have considerable negative effects on the environment, including, but not limited to global warming. Renewable energy is today the world’s fastest growing energy source limiting the negative consequences of growing energy use. The commercial and residential buildings stands together for about 40 % of the total energy usage. Residential buildings alone stands for 20 % of the total world delivered energy consumption by end-use sector. In EU the average residential energy use amounts to 25 % and for individual countries like Sweden and Finland it is 21 %. The EU energy efficiency directive from year 2012 sets a target to save 20 % of the unions primary energy usage by year 2020 compared to the year 1990. The EU countries also agreed in October 2014 on a new energy efficiency target of at least 27 % by the year 2030. To reach this goal, improved energy efficiency are required in all sectors. Finland’s energy efficiency law for buildings from 2013 greatly reduces the minimum energy usage allowed for new buildings. Finland is also preparing for a new law that would by 2020 require all new buildings to be zero or close to zero energy buildings. This is defined by the Ministry of the Environment as buildings that have very high energy efficiency, where the already greatly reduced energy demand is satisfied extensively by renewable energy. As part of the goal to greatly increase buildings energy efficiency, this work focus on heat exchangers for showers. The purpose of this project is to investigate how two different heat exchangers works for shower cabins. This is done by testing a system where the heat exchangers are linked together. The system works by transferring heat from the drainage water and the moist air to the incoming colder drinking water before the cold water is heated in the mixerto desired shower temperature. The measurements are taken for different simulated shower situations. The Heat exchangers efficiency are calculated and the energy savings are examined with annual energy savings. The payback time shows that the system is not currently viable. The efficiency need to be improved, the main issue being the constituent materials heat transfer attributes between cold and hot water. The results are discussed and it is concluded that the system would be viable with improved heat exchanger efficiency and adequate shower use, which depends on the user and the amount of people using the shower. The main issue with increased heat transfer efficiency is the greater risk of contamination between the incoming cold drinking water and the outgoing dirty drainage water.

Självförsörjande småhus gör att beroendet av de kommunala näten försvinner ochflexibiliteten ökar. Det finns fortfarande stor potential till utveckling av tekniska lösningaräven om mycket teknik redan finns på marknaden för exempelvis elproduktion,säsongslagring, uppvärmning, vatten och avlopps samt ventilation. Helt förnybaraenergikällor behöver prioriteras och en övergång till dessa kräver en förändring ibeteendemönster och mer energieffektivt byggande för att minska energianvändningen.Vid utformning av självförsörjande hus kan med fördel solen användas vilket kan påverkaorientering och taklutning. Ytterligare aspekter som kan tas hänsyn till är valet avbyggnadsmaterial, teknikutrymme, klimatskalets uppbyggnad och dispositionen avplanlösningen. / Self-sufficient small housing makes the dependence of the municipal sustentation to minimizeand the flexibility increases. There is still a high potential for developing technical solutionseven though a lot of the technology already exists on the market regarding for examplesolutions for energy production, seasonal storage, heating, water supply, draining system andventilation. Renewable energy sources need to priorities and a transition to 100 % renewableenergy require a change in pattern of behavior and more energy efficient buildings to lowerthe consumption. When designing self-sufficient houses, the sun is a good source for both energy and heatingwhich can have an impact on the orientation of the building and the slope of the roof. Otheraspects to consider can be the choice of building material, technical space, the climate shelland the disposition of the plan.