D. APPENDIX D. DIMENSIONS OF PARTITIONS APPLIED IN CALCULATIONS <br>

D. APPENDIX D. DIMENSIONS OF PARTITIONS APPLIED IN CALCULATIONS

Heated space of considered building should be clearly defined before performing of calculation of seasonal heat demand. It will enable receiving of correct calculation results.

Building elements, which will be considered in calculations are the limits of heated space. If calculations are performed for a part of a building, the limits of these parts should be also clearly defined, so the sum of coefficients of heat losses by penetration of all parts will be equal to the coefficient for entire building.

To perform the calculations it is necessary to divide the building housing into elements. Dimensions of a building element are usually measured according to one of three systems:

- internal dimension – length measured from wall to wall and from the floor to the ceiling inside of each compartment in the building,

- total internal dimension – length measured inside of the building, without taking into consideration the internal divisions,

- external dimension – length measured on external side of the building.

These systems differ from each other in the method of incorporating of flat surfaces of joints between elements in the area of these elements.

The product of the partition area and its heat transfer coefficient is bigger with application of external dimensions, than with application of internal dimensions. As a result, the values of linear heat transfer coefficient of a heat leakage bridge are principally smaller for internal dimensions and in some cases they can have even a negative value – for example for external corners.

If the fundamental insulation layer is continuous, linear heat transfer coefficients of some joints can be small, particularly when internal dimensions or total internal dimensions are applied. In such cases they are often omitted. As a result, in calculated values of coefficient of heat losses by penetration small differences between dimensions systems can appear, when some heat leakage bridges are neglected in one system, and not neglected in the other.

These differences between systems should be taken into account by selection of addition because of occurring linear heat leakage bridges.

Point-type heat leakage bridges can be taken into account by adequate increasing of mentioned addition to the heat transfer coefficient.