Beräkningsstandard för ljudisolering

Sammanfattning: The purpose of this Master Thesis is to observe how well the standard EN 12354, the computer program Bastian, and field measurements agree with each other. Calculations on two different objects, where one object cointained four different constructions, were compared with data from field measurments. The restrictions of EN 12354-1&2 and Bastian were evaluated from this. The areas of application were also evaluated to see if measurments can be replaced with calculations that are conveyed in SS 25267. A new standard, EN 12354, was delivered in the year 2000. It estimates the acoustic performance of buildings from the performance of elements. This was due to the effects of a new testing standard in laboratories in Germany. Earlier, the laboratories were built as two rooms to get a total value of the sound insulation of the building including the flanking transmission. Today, the sound insulation is measured through a building element to get the lab value. In EN 12354-1&2, the lab value is used to get the total value of the airborne and impact sound insulation. The elements vibration reduction index, Kij, has to be known due to the standard. Kij can be counted when the vibration field in the element diffuse and there is no significant decrease in vibration with the distance across the element. This restricts the calculations to monolithic elements. To understand the standard, a hand calculation of airborne sound insulation was performed. A comparison with the calculation of the same object in Bastian gives a difference of around 2 dB. This is acceptable since there’s an insecurity of the calculations. Bastian is a computer program that is used as a calculation tool to EN 12354 1-3, where part 3 deals with airborne sound insulation against outdoor sound. The Bastian database contains about 1600 constructions. In-depth experience in the areas of building construction and building materials is necessary to handle Bastian. If an element or additional layer is missing in the database, it’s possible to enter a new one. According to the field measurements, when compared with the calculations in Bastian on the object, EN 12354 performs well for homogeneous elements. The calculations also show that Bastian is a good calculating tool according to the standard and also on double elements. The more layers in the calculations, the harder it is to approximate a value. Bastian can be used as a control tool before the measurement, but it is not suitable as said in SS 25267 to use calculations instead of measurements.