Buildings and structures that have always functioned as they should often fail to comply with the standards and directives that apply to new building structures. This is often the reason why a constructional approach is taken for these buildings and structures.
However, TNO's research shows that often only minor adaptations rather than major renovation or demolition are necessary for these buildings to once again be able to comply with the standards and directives. TNO is familiar with the background to the standards and directives like the NEN 6700 series (reliability of building structures) and the Buildings Decree and knows how these should be interpreted. Since existing structures often have a shorter lifetime than new structures, the safety factors (at the same level of safety) may be lower and thus can still be applied and comply with the standards. For new structures the material properties and stresses on the structure are uncertain; for existing structures this uncertainty is much less. However, since constructional stresses can be measured, the uncertainty can be more or less removed. What is also known is that the structure has survived the stresses of the past, which removes some of the uncertainty. These two facts reduce the level of uncertainty and boost the reliability and/or safety.