Indoor Humidity Risk Graph

Using the Indoor Humidity Risk Graph for a
Prompt Analysis of the Office Climate

If office workers complain about inadequate temperatures or air humidity, or if respiratory diseases are occurring frequently, the following procedure offers a quick and simple possibility for an initial objective analysis and assessment of the indoor climate. It is based on the “climate risk graph” recommended by deutsche Gesetzliche Unfallversicherung [German Social Accident Insurance] (DGUV) in notification 215-510 on assessing the indoor climate. However, since this DGUV risk graph only applies to complaints about high indoor temperatures and high indoor humidity, Condair has developed a “indoor humidity Risk Graph” for a dry indoor climate.

How should this risk graph be used and what results does it provide?

Step 1:
In offices where there are complaints about a dry, uncomfortable indoor climate, the indoor temperatures and air humidities are measured.

Step 2:
The measured values are entered in the humidity risk graph: the temperature on the x-axis, the relative humidity along the oblique indoor humidity lines.

Step 3:
The application of the humidity risk graph is shown in the two examples opposite.

Example 1: Action required
This applies, for example, to an indoor temperature of 22°C and indoor humidity of 30%. These values result in the intersection point A in the diagram. A horizontal line is drawn from this point to the left edge of the graph (y-axis) to point B. Point B is then connected to the indoor humidity scale on the far left of the diagram, to the measured indoor humidity value (30% in the example). The resulting red line runs through the red area of the risk graph.

This area signals insufficient indoor humidity and consequential health hazards. If the result line crosses the red area of the risk graph, increasing the relative indoor humidity is recommended from a medical viewpoint.
Risikograph 1
Example 2: Optimum indoor air humidity
In comparison, this example with the green lines in the risk graph shows a favourable indoor climate with sufficient indoor humidity. An indoor temperature of 22°C and a relative indoor humidity of 50% were measured. This results in the intersection point C, from which a horizontal line is once again drawn to the left edge of the graph to point D. By connecting point D with the humidity scale beside the diagram to the measured humidity value of 50%, the resulting straight line now leads through the green area. This area indicates sufficient or good indoor air humidity and a resulting low risk of health impairments or hazards due to excessively dry air.
Risikograph 2
Increasing the indoor humidity is also recommended if the straight line runs in the neutral zone between the red and the green area in the indoor humidity risk graph.