Facade degradation risks in relation to energy renovation: towards a clear decision framework

Facade degradation risks in relation to energy renovation: towards a clear decision framework
UKCMB Web Admin

Facade degradation risks in relation to energy renovation: towards a clear decision framework

FWO (Research Foundation Flanders) research scholarship grant number 1S71922N

PhD Researcher: Kaat Janssens (Ghent University)

Supervisors: Nathan Van Den Bossche (Ghent University), Dr Valentina Marincioni (UCL)


Over the last two decades significant research efforts have been done to study the hygrothermal behaviour  of  building  components.  Today,  several  simulation  models  (e.g.  Wufi,  Delphin)  are  commercially available at low prices, and there is an international standard EN 15026 that provides a  number  of  guidelines  concerning  the  simulation  approach.  These  numerical  simulation  models  allow to predict the hygrothermal response of building components subjected to climatic boundary conditions, and use the output to help assess the risk for premature deterioration due to freeze-thaw damage, mould growth, corrosion, wood decay, algae growth and salt damage (Straube and Schumacher  2006,  Guizzardi  et  al.  2015,  Zhou  et  al.  2020).  Both  for  new  constructions  as  well  as  existing  buildings  it  provides  a  valuable  tool  to  go  beyond  very  conservative  rules  of  thumb,  and  enables specific solutions tailored to the case at hand. However, the adoption and application of these tools in practice remains limited. One of the main reasons is the sensitivity of the output to specific  input  variables,  that  requires  a  thorough  understanding  of  material  moisture  storage  functions  and  transfer  processes  (Calle,  2020).  Furthermore,  there  are  a  number  of  challenges  in  the field of hygrothermal simulations:

  • Material properties are  very  difficult  to  measure,  and  liquid  transport  functions  rely  on  indirect measurements and fitting algorithms, which entails inherent uncertainties
  • Variability in material properties can have a significant impact on degradation risks due to non-linear effects and performance criteria with threshold values
  • The impact of  deficiencies  such  as  air  leakage  and  rain  water  infiltration  is  difficult  to  quantify, as these require experimental research and the assessment of the likelihood
  • Most degradation models  and  criteria  are  not  implemented  in  the  commercial  software  packages,    which    typically    requires    additional    post-processing    in    a    programming    environment (R, Matlab, Python)

About the research aims

These challenges again hamper the straightforward use of simulation models in practice, and will not be tackled in the next decade. Hence,  this  research  proposal  aims  to  develop  a  methodology  to  convey  the  results  and  insights  from extensive hygrothermal simulations to the building industry. The use of hygrothermal models can be structured as follows:

  • Guideline to run simulations by building practitioners
  • Building practitioners can access the results of general simulations directly in a database
  • Building practitioners can  provide  a  variable  degree  of  detail  on  the  input  variables  and  receive a comprehensive overview of the results
  • Decision trees steward  building  practitioners  to  assess  the  performance  of  specific  configurations
  • Rules of thumb and technical guidelines are derived from simulations

Taking part in research

You are invited to take part in this project, as a retrofit practitioner or as an occupant, to test the tools provided and developed in this research. Please contact Kaat Janssens if you wish to participate.

Contact for further information

Please contact Kaat Janssens at Kaat.Janssens@ugent.be if you have any queries about this research. You can also contact ukcmb@ucl.ac.uk.