List with building parts

Shading reduction factor

The shading reduction factors are used to determine the heating- and cooling demand of the building, as well as being used for the solar energy systems (solar heat and solar current).

The shading reduction factors are not given per month, but rather they are determined using a weighted average over the whole year.

The shading reduction factors can be specified only if Custom shading reduction factors was chosen in Project Settings.

A distinction is made between obstructions seen from the ground (canopies, roof overhangs etc.) and obstructions seen from the sky (overhangs). The calculations only take into account obstructions on the own building.

To determine the shading reduction factor relatively easily, first the relative height of the shed (or the relative width of an overhang) should be determined. The relative height is defined as the height difference between the centre of the solar incidence plane and the highest point of the obstruction relative to the centre of the solar incidence plane, divided by their mutual horizontal distance.

See figure in norm:

The relative width of an overhang is obtained by determining the farthest point P of the side shed seen from the centre of the solar incidence plane. The distance is now defined as the length from P to the centre of the solar incidence plane. The width is the length from P to the centre of the solar incidence plane measured perpendicular to the solar incidence plane. The relative width of the overhang is obtained by dividing the distance by the width.

See figure in norm:

The relative height of overhangs should be determined first in cases of these overhangs. First, the difference in height is determined between the centre of the solar incidence plane and the lowest point of the obstruction, as computed from the centre of the relevant plane. This height difference is then divided by their mutual horizontal distance to obtain the relative height.

The shading reduction factors can now be determined for the following situations:

Minimal obstructions

§ The building plot does not contain obstructions with a relative height greater than 0.36 m;

§ The building plot does not contain side sheds with a relative width less than 3.73 m;

§ The building plot does not contain overhangs with a relative height less than 1.00 m;

Obstructions with constant height relative to the solar incidence plane

§ The relevant solar incidence plane is horizontal;

§ The building plot does contain an obstruction with a constant height parallel to the solar incidence plane;

§ The building plot does not contain side sheds with a relative width less than 3.73 m;

§ The building plot does not contain overhangs with a relative height less than 1.00 m;

Overhang parallel to the solar incidence plane

§ The relevant solar incidence plane is vertical;

§ The building plot does not contain obstructions with a relative height greater than 0.36 m (residential function);

§ The building plot does not contain side sheds with a relative width less than 3.73 m (residential function);

§ The building plot does contain an overhang with a constant height and parallel to the solar incidence plane;

Overhang perpendicular to the solar incidence plane

•      The relevant solar incidence plane is vertical for heating- and cooling demand;

•      For cooling demand, the side shed is at least 2.5 m higher at its lowest point then the upper side of the solar incidence plane;

•      The building plot does contain a side shed with a relative width less than 3.73 m;

•      The building plot does not contain obstructions with a relative height greater than 0.36 m;

•      The building plot does not contain overhangs with a relative height less than 1.00 m;

Full obstructions

•      The building plot does contain an obstruction with a relative height greater than 0.36 m;

•      The building plot does contain an overhang with a relative height less than 1.00 m;

The shading reduction factor can be extracted from various tables (Tables 21.4 t / m 21:15) depending on the heating demand, cooling demand, solar energy system, and the shading. These factors are presented for a variety of plane orientations and slopes. In case of intermediate values of these orientation and slope, the closes values from the table should be assumed.

Table 17: Shading reduction factors with minimal obstruction for vertical and upwardly inclined facing surfaces.

Table 18: Shading reduction factors with minimal obstruction for vertical and downwardly inclined facing surfaces.

Fictitious

The column Fictitious allows you to consider a building part as virtual.

Reveal [mm]

 BS
The depth of the reveal (in millimetres) can be specified in the columns reveal [mm].