Envelope
A wooden façade functions as a building envelope, protecting the load-bearing structure from the environment, and serving as an important aesthetic design element. Every wooden façade is unique, and several factors will be decisive for its durability and visual appearance. The aim of WBB has been to enable construction of wooden urban building envelopes with long lasting and predictable quality, where architectonical innovation will be supported by optimal choice of material, details and wood protection.
Involved partners: NIBIO, NMBU, AHO
Key research:
Prediction of service life - modelling
The project has combined the latest models predicting climate exposure on buildings with the deterioration models to build a combined model for predicting service life. The model simulates and predicts future service life in urban wooden architecture, and enables knowledge-based decisions regarding design and material selection. This interdisciplinary approach is new, not only in Norway, but also internationally.
Hyperspectral imaging of weathered wood samples in transmission mode
by Sandak, Anna; Burud, Ingunn; Flø, Andreas Svarstad; Thiis, Thomas Kringlebotn; Gobakken, Lone Ross; Sandak, Jakub
International Wood Products Journal 2016
The proposed methodology was able to scrutinise differences in degradation of earlywood and latewood, hence provided new understanding for the kinetic of the weathering process of wooden façades.
Application of simple surface climate models for modelling mould growth on wooden façades
by Thiis, Thomas Kringlebotn; Burud, Ingunn; Kraniotis, Dimitrios; Gobakken, Lone Ross
I: Structures and Architecture Beyond their Limits. Taylor & Francis 2016 ISBN 978-1-138-02651-3. s. 615-623
Simple models have been developed for surface temperature and moisture on a wooden façade for use with mould growth models. The models are driven by exterior climate data combined with ray-tracing to account for the microscale variations of the solar irradiance on the wall. The models are applied to a façade made of untreated aspen and the results are compared to measurements of temperature and moisture in the façade.
Near infrared hyperspectral imaging in transmission mode: assessing the weathering of thin wood samples.
By Smeland, Knut Arne; Liland, Kristian Hovde; Sandak, Jakub; Sandak, Anna; Gobakken, Lone Ross; Thiis, Thomas Kringlebotn; Burud, Ingunn.
In Journal of Near Infrared Spectroscopy 2016 ;Volum 24.(6) s. 595-604
The degradation of earlywood and latewood was modelled as a function of UV solar radiation with four regression techniques. It was found that all the techniques yielded robust prediction models on this dataset.
The role of transient wetting on mould growth on wooden claddings
By Thiis, Thomas Kringlebotn; Burud, Ingunn; Kraniotis, Dimitrios; Gobakken, Lone Ross
In Energy Procedia 2015; Volum 78. s. 249-254
This study analyses the effect of variations of meteorological data on the mould growth on wooden claddings. An experimental setup of wood samples was exposed to outdoor conditions and hourly weather conditions as well as the mould growth at different intervals were measured. The measurements were supplied with 1-D Heat And Moisture (HAM) simulations to provide a more accurate estimate of the conditions on the surface of the samples.
The purpose of the analysis was to evaluate if an existing mould growth model might be applicable also for predicting outdoor mould growth. Several profiles of temperature and moisture were continuously monitored on different locations of an eight-story building made from Cross Laminated Timber (CLT). The results from the analysis of the samples of wood cladding were used to model the mould growth on different locations of the building. Also the drying effect of wind around the building was studied. The study shows that there is large variation of potential mould growth on the façade of the building.
Assessment of the use of dynamic mechanical analysis to investigate initial onset of brown rot decay of Scots pine (Pinus sylvestris L.).
by Ormondroyd, G. A.; Alfredsen, Gry; Durai Prabhakaran, R.T.; Curling, Simon; Stefanowski, B. K.; Spear, M. J.; Gobakken, Lone Ross
International Biodeterioration & Biodegradation 2017 Volum 120. s.1-5
Prediction of service life - tests
Field tests and laboratory experiments have been performed for verification and further development of the new combined prediction and simulation model.
By Sandak, Anna; Burud, Ingunn; Flø, Andreas Svarstad; Thiis, Thomas Kringlebotn; Gobakken, Lone Ross; Sandak, Jakub.
In International Wood Products Journal 2016
This study provided new insight regarding the kinetics of the degradation rate of wooden samples. The experimental specimens were weathered at 15 locations in Europe for a period of 1 month and hyperspectral imaging was used for evaluation of earlywood and latewood degradation.
Weathering kinetics of thin wood veneers assessed with near infrared spectroscopy.
By Sandak, Anna; Sandak, Jakub; Burud, Ingunn; Gobakken, Lone Ross
In Journal of Near Infrared Spectroscopy 2016; Volum 24.(6) s. 549-553
The degradation of thin wooden samples exposed to short-term weathering has been analysed. Tests were performed through the European summer (July) which is considered the most severe period for weathering of wood micro-sessions.
Near infrared hyperspectral imaging in transmission mode: assessing the weathering of thin wood samples.
By Smeland, Knut Arne; Liland, Kristian Hovde; Sandak, Jakub; Sandak, Anna; Gobakken, Lone Ross; Thiis, Thomas Kringlebotn; Burud, Ingunn.
In Journal of Near Infrared Spectroscopy 2016; Volum 24.(6) s. 595-604
Several sets of samples were exposed outdoors for time intervals from 0 days to 21 days, and one set of samples was exposed to ultraviolet (UV) radiation in a laboratory chamber. The degradation of earlywood and latewood was modelled as a function of UV solar radiation with four regression techniques. It was found that all the techniques yielded robust prediction models on this dataset. The results pave the way to a weather dose model determined by temperature and moisture content on the wooden surface in addition to the solar radiation.
Hyperspectral near infrared imaging of wooden surfaces performed outdoors and indoors.
By Burud, Ingunn; Gobakken, Lone Ross; Flø, Andreas Svarstad; Thiis, Thomas Kringlebotn; Kvaal, Knut.
In NIR news 2015; Volum 26.(1) s. 4-7
Hyperspectral measurements were carried out both outdoors and indoors in order to explore the influence of the different light conditions on fungal growth for a variety of wood substrates.
The wood substrates exposed in an outdoor environment will have a colour change due to photo degradation of lignin, wetting/leaching of the upper layer of the wood surface and growth of a variety of wood discolouring fungi.
The role of transient wetting on mould growth on wooden claddings
By Thiis, Thomas Kringlebotn; Burud, Ingunn; Kraniotis, Dimitrios; Gobakken, Lone Ross
In Energy Procedia 2015; Volum 78. s. 249-254
This paper analyses the effect of variations of meteorological data on the mould growth on wooden claddings. An experimental setup of wood samples was exposed to outdoor conditions and hourly weather conditions as well as the mould growth at different intervals were measured.
The measurements were supplied with 1-D Heat And Moisture (HAM) simulations to provide a more accurate estimate of the conditions on the surface of the samples. The purpose of the analysis was to evaluate if an existing mould growth model might be applicable also for predicting outdoor mould growth. Several profiles of temperature and moisture were continuously monitored on different locations of an eight-story building made from Cross Laminated Timber (CLT). The results from the analysis of the samples of wood cladding were used to model the mould growth on different locations of the building. Also the drying effect of wind around the building was studied. The study shows that there is large variation of potential mould growth on the façade of the building.
Hyperspectral imaging of blue stain fungi on coated and uncoated wooden surfaces.
By Burud, Ingunn; Gobakken, Lone Ross; Flø, Andreas Svarstad; Kvaal, Knut; Thiis, Thomas Kringlebotn (2014)
In International Biodeterioration & Biodegradation 2014 (0964-8305) Vol. 88, s. 37-43
Hyperspectral imaging has been applied on samples of coated and uncoated Norway spruce (Picea abies) to detect and quantify blue stain fungi that has colonized and grown on the surface of the samples. A clear visualization of the fungi was obtained through a Principal Component Analysis of the hyperspectral images and the amount of mould coverage could be estimated for each sample. The signal from the fungi on the hyperspectral images in near-infrared wavelengths could clearly be distinguished from water and moisture on the samples. The results indicate that NIR hyperspectral imaging can be used as a tool for assessing coverage of surface fungi and event spectral classification of the two fungal species Aureobasidium pullulans and Cladosporium cladosporioides.
Visual appearance
The project has revisited and documented a number of unpainted timber clad buildings from the 1990s. The study has been translated into a visual guide to colour changes in unpainted timber facades as a customized tool for architects, contractors, developers and engineers. The aim of the guide is to enable an optimal utilization of timber façade materials, based on design, durability, accessibility, climatic exposure and environmental impact.
Det levende materialet. Bruk av tre i fasader og uterom.
by Gobakken, Lone Ross; Treu, Andreas; Zimmer, Katrin
Arkitektur N 2016 (7/8)
Fargeendring i umalte trefasader
by K. Zimmer, O. Flindall, L. R. Gobakken and M. Nygaard
NIBIO, 2017
by Solrun Karlsen Lie
NIBIO, expected 2019
The PhD-study focuses on surface mould growth on unpainted wood. Mould growth is one of the most important contributors to the grey colour development during the weathering process. Mould growth varies with different climatic exposure and material properties. This is investigated in laboratory experiments and in field tests, and the data will be used as input to the models predicting service life.