Wooden façades predicting and simulating service life and aesthetical properties

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2 Wooden façades predicting and simulating service life and aesthetical properties The Wood Be Better project Increased use of wood in urban areas Lone Ross Gobakken, PhD

3 WOOD IN-SERVICE

4 Contemporary housing Multi-story and non-residential buildings

5 WOOD AND ITS ROLE IN THE GREEN SHIFT Long-lived wood products will contribute to a low carbon footprint because: living trees sequester carbon harvested wood products act as carbon sinks during their service life Principles how to utilize and maximize this carbon sink: 1. increased utilization of wood in buildings (substitution) 2. prolonging the service life of wood in its primary applications in buildings 3. facilitating reuse and reclamation of wood 5

6 WOOD/BE/BETTER Increased use of wood in urban areas , 2.6 million EURO, national funded Main aims: to produce and publicize knowledge that will facilitate increased use of wood in buildings in urban areas (focus on 2-5 storey buildings) facilitate communication between architects, building owner, entrepreneurs, civil engineers, mycologist and wood scientists WP1 - Urbanisation, sustainable buildings and utilisation of wood WP2 - Design based research WP3 - Constructive solutions and material requirements for important building types WP4 - Wood based climate envelopes in urban architecture WP5 - Integration of wood competence in interdisciplinary project processes 3 PhD-students WP1, WP3 and WP4 6

7 Harvard Center for Green Buildings and Cities

8 Wooden façades are a vital and material intensive part of a building Wooden façades act as the face towards the public and are the ambassador for wood in buildings Extending the life-time of wood by: prevent wood from degrading and losing its functional attributes strengthen the confidence and positive perception of wood façades Challenges to overcome: Decay and mould fungi + fire + insects + negative perception of wood

9 Visual appearance changes due to weathering

10 WOODEN FAÇADES AND AESTHETICS The benefits of using uncoated wood; low cost for maintenance low environmental impact a contemporary look a breathable envelope Aim for homogenous colour and pattern - and mimicking of the aesthetic appearance of older barns and mountain huts The weather gray surface color is caused by: photo degradation of lignin wetting/leaching of the upper layer of the wood surface growth of wood discoloring fungi 10

11 Rena military camp, Rena Cladding in Pine

12 Svartlamoen, Trondheim Cross laminated timber and cladding in pine Photo: William Fairminer

13 AIM 1) Predict the weathering effect on wooden facades over time 2) Visualize the weathering effect over time 3) Add-on to Building Information Modeling (BIM) (plan, design and construct a building) METHODS Lab tests, climate chamber tests, field tests and in-service studies Development of evaluation tools/methods Model the micro climate on the wooden surface Develop performance models; weathering, mould growth and decay Simulation models 13

14 Influencing factors Maintanance Workmanship Wood properties Coating Wood substrate Exposure time Weathering and fungal growth Material climate t/rh/wmc Surface structure Manufacturing characteristics Colour Climate micro/meso Design

15 Influencing factors Uncoated Coated Exposure time Wood substrate Wood properties Coating Colour Manufacturing characteristics Surface structure Workmanship Design Material climate Cardinal direction Climate (meso / macro) +++=great impact ++=moderate impact +=impact - =no impact ( ) = expert opinion/inspections *=depends on the type/product of coating * +++ +* N/A +++ (++) ++ (+) -* (++) ++ (++) (++) (+++) (+) Gobakken 2009; Gobakken, Bardage & Long II 2011; Gobakken & Vestøl 2012; Gobakken, Gellerich, Høibø & Militz 2014; Gobakken & Vestøl 2015

16 Lab and climate chamber tests mould growth resistance After 28 days Mould After After 28 days 84 days After 84 days Tukey-Kramer growth MR Tukey-Kramer MR Tukey-Kramer MR 85 MR % RH Alder A 4.00 A A A C Ash A 4.00 A A A 4h wetting/day 4.00 Beech A 4.00 A A A 4.00 ce, Norway 3mm A spruce, 3mm 4.00 A A A % RH ce, Norway 1mm A spruce, 1mm 4.00 A A A C Sitka spruce A 4.00 A A A 4h wetting/day 4.00 Aspen A 3.83 A A A 4.00 ch European A larch 3.75 A A A 4.00 od. Thermally pine A mod. pine 3.75 A A A 4.00 Birch A 3.25 A A A 4.00 ine Acetylated B pine 1.83 B A A % RH ine DMDHEU, B pine 1.50 B A A C Douglas fir B C 1.17 B A C B A B 4h wetting/day 2.75 Oak B C 1.08 B C B C B C 2.00 pwood Scots pine sapwood B C 1.00 B C B C B C 2.00 pine Furfurylated pine C D 0.42 C B D C 0.42 D 1.25 B C D 1.25 e Cu HDO, pine D 0.00 D C 0.00 D 0.25 C D % RH CCA, pine D 0.00 D 0.00 D 0.00 D C QN, pine D 0.00 D 0.00 D 0.00 D h wetting/day cedar Western red cedar D 0.00 D 0.00 D 0.00 D 0.00 MR=Mould rating (0-4) after 28 days Day 1 Aspen Day 91 Gobakken & Alfredsen 2016; Lie 2015, Lie, Gobakken, Vestøl & Høibø 2017ab; Curling & Gobakken 2017

17 Field tests 3 months outdoors Spruce Pine Cu-imp pine Metal-free imp pine 3 years outdoors 3 months outdoors Acetylated pine Thermal pine Furfurylated pine Royal imp pine 3 years outdoors Gobakken 2009, Gobakken; Høibø & Solheim 2010; Meyer-Veltrup & Gobakken 2017; Zimmer, Flindall, Gobakken & Nygaard 2017

18 In-service studies Moderate growth of Aureobasidium pullulans Heavy growth of Aureobasidium pullulans Heavy growth of Aureobasidium pullulans

19 Predicting service life and aesthetic appearance Combining several models: Models for fungal discoloration Models for weathering Microclimatic models Perform simulations: In-put: solar radiation + temperature + relative humidity Out-put: mould growth and weathering in the façade over time Gobakken & Lebow 2009; Thelandersson & Isaksson 2013; Thiis, Burud, Kraniotis & Gobakken 2015a; Thiis, Burud, Kraniotis & Gobakken 2015b; Thiis, Burud, Kraniotis & Gobakken 2016

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21 kwh/m2 % kwh/m2 % kwh/m2 % kwh/m2 % Deg C Deg C 0 0 Deg C Deg C Annual total solar radiation Annual mean temperature Mould rating Mould rating Mould rating Mould rating RH Annual mean RH MRD mould rating Simulations was run for 8770 hours on the test object (south façade, Ås videregående skole, Norway)

22 Mould rating 81 Mould rating

23 Color changes in unpainted wooden facades gained experience and case studies

24 Authors: Katrin Zimmer, Ona Flindal, Lone Ross Gobakken, Marius Nygaard WoodBeBetter, NIBIO and AHO Color changes in unpainted wooden facades gained experience and case studies

25 ONGOING AND FUTURE WORK Further development of hyperspectral imaging for detection of deterioration and changes in the surface Expand the simulation platform ; decay risk and maintenance needs Monitoring and inspection of large and tall buildings with drones and multi-sensory equipment Lesar et al 2017; Stefansson, Burud, Thiis, Gobakken & Larnøy 2017; Alfredsenet al 2016; Burud, Stefansson, Thiis & Gobakken in-prep; Burud, Gobakken, Flø & Thiis in-prep; Gobakken, Burud & Flø in-prep

26 Increase the general knowledge of wooden façades, design, wood properties, climate and mycology to: create durable and long-lived woodbased building envelopes enable knowledge-based decisions regarding design and material selection use fungal discoloration and weathering as a design option predict and control the future aesthetic and technical performance of a wooden façade identify wood materials that are Fit For Purpose Solbergtårnet rest area, Skjeberg Cladding in western red cedar Increase the use of wood and secure a favourable perception of wood.

27 Thank you! nibio.no