Probabilistic approach to the assessment of uncertain input parameters when energy renovating existing buildings

Sammanfattning: Since the building stock stands for significant part of the EU’s total energy use, energy renovations are needed in order to lower the negative environmental impacts. In Sweden, only 1 % of the total building stock is newly built i.e. the focus should be directed upon existing buildings. Moreover, most of the buildings in the “Million Program” from 1970´s are in need of renovations in order to keep them operational. This makes for excellent opportunity to energy renovate these buildings at the same time, and follow up the work that can later be implemented to all other types of existing buildings. This project is about trying to determine an existing building total energy use over a year, which is the main question that needs to be answered when it comes to determining the viability of energy renovations on existing buildings. For this, computational simulations were performed as well as statistical methods such as sensitivity analysis and Monte Carlo simulations. The statistical methods are used instead of performing conventional expensive and time-consuming measurements, when obtaining the values of the input parameters used for the simulation tool. In addition, installing the heat recovery on the current ventilation system is also looked upon in order to see what additional energy savings could be made. The results show that the building total yearly energy use should lie within the interval of about 160-190 kWh/(m2·year) and that the average use should be around 177 kWh/(m2·year). After installing a heat recovery system, the building total energy use should lie between 115-135 kWh/(m2·year), which is a decrease of around 24-35 % in total energy savings.