The Earth’s climate is getting warmer. Combustion of carbon dioxide is one of themain causes and results in increased levels of greenhouse gases that Earth’s vegetation is unable to carry, which ends up outside Earth’s natural cycle. In order to achieve an ecological sustainability, Sweden and EU has set climate and energy targets for 2020 and 2030, to encourage energy efficiency, energy savings and development of new and renewable energy sources. Akademiska Hus, is one of Sweden's largest property companies and their goal is to reduce the amount of purchased energy by 50% until 2025. This study was made in cooperation with Akademiska Hus and aims to investigate the possibilities of utilising waste heat from the district cooling return for Ulls Husby implementing a heat exchanger which preheats the supply air in the ventilation system for the building. The goal is to examine if the solution is realizable and profitable, and to create a basis for future implementation of heat recovery in several of Akademiska Hus's properties. Calculations regarding power and energy demands are carried out for the current ventilation system without preheating and with an implemented preheating. Seven different test scenarios were investigated to determine when the conditions are favorable for preheating. The payback method is applied to investigate if the implementation is economically profitable. The results show that the purchased energy can be decreased by 1332 kWh for Ulls Hus by preheating the air during the investigated period between 15th October 2018 and 14th April 2019. Preheating decreases the number of power peaks higher than 25 kW in the ventilation system from 160 to 5 peaks. The reduction in energy and power demand is not considered economically profitable with a payback time of 309 years. Optimizing the operation strategy for the ventilation system to eliminate the power demand that occurs during the daily start of the system can decrease the purchased energy without preheating by 1 486 kWh, which correspond to 66%.With preheating the reduction can be additional 816 kWh to the results of preheating. This, as a suggestion, can be done by commissioning the heatexchanger before the rest of the ventilation system starts. The results for the four of the seven test scenarios that including lower temperature efficiency and 24-hour operation, alone or combined with each other and with a regulated supply air, show a larger reduction of purchased energy andthat an implementation can be considered economically profitable with shorter payback times. The four scenarios show a reduction with 62 630 kWh to 122 160 kW hand a pay back time half as short as the technical life expectancy which is considered economically profitable.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-406962 |
| Date | January 2020 |
| Creators | Hasth, Amanda, Modée, Amelia |
| Publisher | Uppsala universitet, Byggteknik, Uppsala universitet, Byggteknik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | Swedish |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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