11/9/2022 0 Comments Iword for nternal value![]() ![]() ![]() Depending on the details a more realistic U-value for this sort of construction might be about 0.25 W m –2 K –1. This will create a ‘thermal bridge’ bypassing the insulation and reducing its performance. The wall construction above is likely to use thin metal wall ties securing the outer brickwork to the inner leaf of blockwork. In practice, building elements do not simply consist of flat layers. Table 6 Calculation of thermal resistances Layer Using the conductivity values in Table 4 we can calculate its U-value by summing the various thermal resistances as shown in Table 6. The U-value of this wall is its inverse = 1/ R T W m –2 K –1įor example the wall shown in Figure 15 consists of the following layers: 115 mm common brick, a 115 mm cavity filled with mineral wool (conductivity 0.035 W m –1 K –1), 115 mm of aerated concrete blockwork (density 460 kg m –3) and a 13 mm layer of plaster on the inside. Taking, for example, a wall construction with four layers, the total thermal resistance, R T, will be: The final resistance at the right represents the inside surface resistance and is labelled 'R' subscript 'S' 'I'. ![]() The next four resistances represent those of different layers of the wall and are labelled ‘R’ subscript ‘1’ to ‘R’ subscript ‘4’. The resistance at the left represents the outside surface thermal resistance and is labelled 'R' subscript 'S' 'O'. This drawing shows a string of six thermal resistances each drawn using the convention for electrical resistances, a zigzag line with a horizontal line at each end. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |