Center for Light and Environmentally-Friendly Structures ZELUBA®

Research project

More than just insulation – Additional benefits of insulation materials made from renewable raw resources

Working area “Moisture protection” / Subsidiary aspect: Composite thermal insulation systems with materials made from renewable raw resources

Within the framework of the collaborative project “More than just insulation - Additional benefits of insulation materials made from renewable raw resources”, we are investigating a subsidiary aspect within the working area of “Moisture protection”. Renewable raw materials (German: nachwachsende Rohstoffe, “NawaRo”) exhibit a high absorption of moisture, which can be beneficial for their application as an insulation material, particularly in the case of prolonged unfavorable moisture conditions. In this context, we are investigating the subsidiary aspect “Composite thermal systems with insulation materials made from renewable raw resources” (NawaRo-WDVS). Our goal is to determine and scientifically prove the potential positive properties of the insulation materials made from renewable raw resources when used in WDVS systems. We thereby examine, in particular, the significantly superior properties with regard to thermal and moisture absorption in comparison to the so-called conventional insulation materials.

Infestation through microorganisms

The infestation of façades through microorganisms, in particular mold and blue stain fungi as well as algae, is an increasing problem due to the following facts:

  • Building physics effects lead to cool surfaces and increased condensation.
  • Plasters and façade paints contain increasing amounts of organic components.
  • Developers and users are more critical and demanding (aesthetic effect).

On many dowelled WDVS, it is clearly recognizable that a slightly higher surface temperature (e.g. in the area of ​​the dowels) leads to a considerably reduced level of infestation. Preliminary tests at the Fraunhofer WKI have shown that an increased thermal absorption in the WDVS can effectively reduce the duration and intensity of the condensation.

In order to prove the positive effect of the higher thermal absorption capacity of NawaRo-WDVS on the probability of infestation and the growth of staining molds, blue stain fungi and algae on the WDVS surface, we perform simulation calculations. By means of numerical simulation, we can also model the behavior of WDVS with regard to its potential for algae formation. In addition to moisture transport and conduction, emphasis is also placed upon thermal absorption. The influence of the material properties, such as bulk density, specific thermal capacity, thermal conductivity and moisture absorption capacity, is being investigated regarding the duration of the sub-dew point state and, consequently, the quantity of condensation. We thereby take into account differing types of plaster as well as exposure of the façades. For the validation of the simulation calculations, we perform selected investigations on the laboratory scale. Material characteristics which are lacking for the numerical simulation are determined through supplementary laboratory tests.

Figures 1 and 2 show the initial results of the simulation calculations. The higher thermal absorption capacity of insulation materials made from renewable raw resources can, in particular on north-facing sides (Figure 2), lead to less condensation forming on the plaster surfaces than with WDVS with insulation materials which exhibit a relatively low thermal absorption capacity (e.g. polystyrene or mineral fiber). This would be initial evidence for the correctness of the assumption that NawaRo-WDVS exhibit a lower probability of infestation. The work, however, is still in its infancy; it is not yet possible to provide a definite answer to the question. 

Simulation of the effects of the differences in the façade insulation material on the formation of condensation
(Infestation with microorganisms)

© Fraunhofer WKI | Norbert Rüther
Figure 1: Temperature and relative humidity on the direct plaster surface, for insulation with wood-fiber insulation panels (WF) and for insulation with polystyrene (PS); here: hypothesis for a south alignment
© Fraunhofer WKI | Norbert Rüther
Figure 2: Temperature and relative humidity on the direct plaster surface, for insulation with wood-fiber insulation panels (WF) and for insulation with polystyrene (PS); here: hypothesis for a north alignment

Damage through leaks

Through leaks in the WDVS, damage can occur which can ultimately lead to the WDVS being rendered unusable and/or to damage to the supporting structure. This applies to NawaRo insulation materials as well as to mineral-fiber insulation and hard foams. There is a need for research concerning the actual damage tolerance of such building materials.

In order to investigate the behavior of imperfect components with WDVS into which water can penetrate through e.g. leakages, we initially form an estimation of the behavior by means of simulation calculations. In this work package, the focus is being placed upon the properties with regard to moisture transport and moisture absorption, in particular compared to insulation materials made from hard foams and mineral fibers. We hereby take particularly into account the different façade colors, type and location of the leakage and different exposures of the façade surfaces. For this, we once again perform selected investigations on the laboratory scale in order to validate the simulation calculations and to determine the material properties lacking in the numerical simulation. 

Funding (collaborative project)

Funded by the Federal Ministry of Food and Agriculture by decision of the German Parliament

Funding body:
Bundesministerium für Ernährung und Landwirtschaft (BMEL)
(German Federal Ministry of Food and Agriculture)

 

Project management:
Fachagentur Nachwachsende Rohstoffe e.V. (FNR)
(Agency for Renewable Resources)

 

FNR funding code:
22011615

 

Duration:
1.12.2016 to 7.5.2020

Fördermittelgeber:
Bundesministerium für Ernährung und Landwirtschaft (BMEL)

 

Projektträger:
Fachagentur Nachwachsende Rohstoffe e.V. (FNR)

 

FNR-Förderkennzeichen:
22011615

 

Laufzeit:
1.12.2016 bis 30.11.2019