Minskad energianvändning, men hur mycket?

Sammanfattning: The following report investigates the Almtuna preschool buildings potential improvements in energy efficiency. Almtuna preschool is owned by Skolfastigheter AB, which is a part of Uppsala Kommun. The preschool is situated in Fålhagen, east from the city centre. In November-December 2015 the old luminous lamps were replaced with the newer technique LED lamps. The results were based on a simulation model of the building in Simulink. The models corresponded closely with the reality. After the change of lamps, the total energy consumption decreased with 14% for January to Mars 2016 compared with the same months for 2011-2015. The findings of the report show that of the potential improvements only the ventilation would be a viable. The report suggests a photo voltaic system of 39 monocrystalline modules from the company JA Solar. These should be placed on the middle roof, and will produce about 10 500 kWh per year which is 16 % of the pre-school electricity consumption. In practice only 14 % of the buildings electricity consumption would be replaced as the electricity from the PV cells will be produced unevenly during the day and it is expected that at certain periods the PV cells will produce too much electricity for the building use. The estimated pay-back period for the investment and installation was 15 years. There is a possibility that the excess electricity produced could be sold to the grid. An alternative option is to store the energy in a battery. The suggested battery for energy storage is LiFePO₄ as it has a long lifespan and a high threshold to withstand up and down charges. The calculated potential energy storage during one year is 250 kWh. The report found however that the most economically viable option would be to sell the excess energy to the electricity network.