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Per definition the Risk Number R(i) is the product of a Measurement Figure M(i) and an Valuation Number B(i):

R(I) = M(i) * B(i)

This definition derives from the general risk definition as it is used in the insurance industries.

The Measurement Figure M(i) constitutes a measured parameter (i) in the form of a dimensionless value. Two different methods of recording the individual Measurement Figure M(i) are used:

— Metrological definable parameters: They are defined by the alteration from the initial zero state to the actual state.

— Numerically recorded parameters: These parameters do not describe the deviation from an initial state. They are available as measured values, which, however, have to be classified according to agreed upon criteria. One example is the quantity of precipitation, where the measured values obtained from environmental stations are scaled to numbers between zero and one according to the rain intensity.

According to the calculation method M(i), it will always be a number between zero and one.

The Valuation Number B(i) indicates how much the respective parameter affects the weathering process. It is limited to values between 0 and 10, which are attributed by the user. For example, a parameter with a great impact on the weathering process is rated 10, another with less impact maybe only 5. In the calculation process, these Value Numbers B(i) are fixed and must not be changed 37because otherwise no comparison would be possible between different investigations.

Several exogenous (climate, exposition) and endogenous (stone properties) parameters influence the integrity of stone figures in the outdoor climate. For calculating their Risk Number R(i) it is necessary to measure these parameters quantitatively. Altogether we use 104 different parameters, which are allocated to 10 Excel data sheets according to their meaning. The 11th data sheet serves for the calculation of the Overall Risk Number R(total), which comprises the individual Risk Numbers R(i) of the other data sheets.

1 Object Description

2 Art historical Evaluation B(AE)

3 Restoration History R(RH)

4 Environment / Exogenous Risk Factors R(E)

5 Natural Stone / Endogenous Risk Factors R(N-M) for Marble

6 Natural Stone / Endogenous Risk Factors R(N-S) for Sandstone

7 Damage Caused by Human Beings / Vandalism R(V)

8 Mechanical Damage / Loss of Material R(M)

9 Surface Alteration R(SF)

10 Ultrasonic Diagnosis R(US)

11 Overall Risk Number R(total)