INFLUENCE OF THE SEALING OF FACADE OPENINGS ON THE ENERGY BALANCE OF A MULTI-FAMILY RESIDENTIAL BUILDING

Abstract

Facade openings, as essential elements of buildings where people live and work, have a great influence on the heat balance of the entire building (up to 40%). With the development and emergence of new materials, the standards for the design of residential buildings also changed regarding the minimum area of openings in relation to the area of the room (according to the standards from 2012, it is 15%). It is necessary, at the same time, to ensure good insulation and sealing, and the possibility of air exchange and transparency. In Serbia, the representation of wooden windows is around 72%, which over time, due to drying, exposure to the sun and temperature differences, lose their volume and become weathered. Considering the condition and age of the joinery and the fact that the certified high performance of new joinery refers to installation in ideal conditions, which in practice is very often not met, in order to achieve energy savings, it is necessary to carry out rehabilitation in order to reduce losses. In most cases, due to the high cost of replacing the complete joinery, it is possible to improve, with various methods, the sealing of the joint between the window sill and the wall (with acrylic materials or mineral wool, if the space is larger, and waterproofing), the sill and the window wing (door) (with rubber moldings or silicone), wings and glass (change of sealants or entire packages of glass) and joints of blind boxes and facade openings (by insulating the space inside the box and the joints of the box with the walls and ceiling). On the specific example of a four-story building with an attic built in 1950, the KnaufTerm2 software analyzed the impact of different levels of sealing of facade openings with the aim of determining, based on the condition, their impact on energy consumption. First, a basic model was made for the existing condition and it was determined that, for the given positions, materials, and other parameters, the building belongs to the energy class "G" and the value of the required annual heating energy of 193.75 kWh/m² was obtained, which is far less from today's requirements when creating projects for the construction of new buildings, which are determined by the Rulebook on conditions and norms for the design of residential buildings and apartments from 2012. After that, two more models were made and in each of them, in relation to the basic model, the parameter that defines the tightness of the facade openings was changed, so that the value of the required annual energy for the model with medium tightness was 165.32 kWh/m², which is 28 .43 kWh/m² less than the basic model, and for the model with good sealing it was 158.22 kWh/m², which is 7.1 kWh/m² less than the basic model, thus both modified models achieved energy class "F". Through such an analysis of the results obtained by changing the parameters, we have an insight into how they affect the required amount of energy for heating the building, i.e. the building's energy class, noting that currently the regulations do not define criteria for determining the quality of sealing.