Page 55 - Build 151

WUFI was widely used in the BRANZ weathertightness research programme with this air ow model. It enabled the drying experiments undertaken on the BRANZ site to be generalised to other locations in the country. This involved thousands of models being run and compared to experimental measurements.
WUFI now available for industry use but still some data gaps
Now, several years later, WUFI is more mature and accessible to those outside the research community. It is being used by the industry in a variety of situations, but this has challenges.
The quality of some of the models and the conclusions drawn can be questionable because of:
● a lack of material data – there is not much currently available for
New Zealand materials
● inappropriateindoorconditionsinputintothemodel
● alackofuserknowledge
● dubious assumptions about the situation being modelled, including
air ows and surface coe cients.
All BRANZ’s work with the WUFI model is tied back to experiments, which is obviously di cult for the majority of industry to do.
Although WUFI now includes New Zealand climate data, there is still work needed to address other issues.
BRANZ working to add more data
As a result, the new BRANZ project plans to address problem areas:
● Material data – it will create a New Zealand/Australia generic materials database, with the possible inclusion of speci c materials.
● Indoorconditions–alongwithseveralotherresearchprojects,this will pull together a resource of measured indoor conditions. It will produce a range of indoor condition data categorised by building type and usage. This dataset will be evaluated against standards
such as ASHRAE 160.
● It will provide guidance for those receiving reports so they know
what to question and who to contact if they need advice.
● It will support and education to help clarify areas of insu cient
practitioner knowledge.
Other activities planned include taking a fresh look at air movement, particularly in narrow cavities, where air velocities can be higher. This may result in a change to the surface transfer coe cients for both heat and moisture from the materials in the space.
Build 151 — December 2015/January 2016 — 53