Energy Audit and Assessment of the Energy Potential of Solar Cells for an Office Building

This thesis is a case study of the application of an energy audit to determine the energy use and potential energy efficiency measures in an office building in Uppsala (Sweden). The motivation of this analysis is the increasing concern about the environmental impact which stems from buildings energy consumption and the interest in an increased sustainability in this sector. Afterwards, in line with the interest in more sustainable buildings, the possibility of installing a grid connected photovoltaic system has been analyzed. The system feasibility has been researched through the creation of a model of the system and the simulation of different possible configurations. The energy audit has involved many tasks. First of all, the plans of the heating, ventilation and air conditioning systems have been analyzed to understand their operation. The data from bills have been also useful to identify tendencies in the electrical and heating energy consumption of the facility. This has allowed to estimate the heating and cooling loads in the building. Afterwards, the facility has been visited to conduct an energy survey. A thorough inspection of the energy systems in the building has been carried out to find possible energy efficiency measures. Besides, the electric power consumption of these systems has been recorded by loggers to analyze its evolution and look into their operation schedule. Measurements of the temperature, light and humidity in the office areas have been taken to assess the indoor comfort in the facility. An inventory of the fans and pumps for the different systems has also been carried out to check and validate the results from the loggers. This process has allowed to allocate the energy use of the different systems and to prepare the energy balance in the building. The results match with the data from the bills and the inspection in the facility. Several energy efficiency measures have been found thanks to the audit, with a potential for energy savings of 126 MWh. The economical analysis of these measures has shown that most of them are profitable, and they can reduce the greenhouse gases emissions by between 5.87 and 59.4 tons of annual equivalent CO2 depending on the applied approach to estimate the effect of electricity production in greenhouse gases emissions. On the other hand, the study of the photovoltaic system has been done through computer simulations with PVsyst. The use of PVsyst has been vital because there are several factors to take into account when designing a photovoltaic system. The meteorological data for Uppsala have been taken from different sources, but only the data from the database Meteonorm have been proved to be reliable for the simulations. The next step has been the creation of a 3D model of the building and the system to reflect the effect of shadings in the system. Then, several configurations with different tilt angles and pitches have been compared to find the one with the best performance. The optimal configuration - tilt angle of 10 _ and pitch of 3 m - has led to the highest performance ratio and electricity production. This configuration has been used to perform a deeper comparison between modules and inverters from different manufacturers. The best combination regarding the electricity production and performance ratio is the use of a PV module from Renewable Energy Corporation and an inverter from AEG, with a performance ratio of 0.821 and a yearly electricity production of 30.1 MWh. However, this configuration does not produce any energy surplus that can be sold to a utility company. An economical analysis using two sets of prices has shown that the total investment for the considered system would lie between 244000-1189000 SEK, with a payback period of 10 to 47 years, and therefore would not be economically feasible.