Impact of climate change on wood deterioration

Institut für Berufswissenschaften im Bauwesen

Impact of climate change on wood deterioration Challenges and solutions for cultural heritage and modern structures C Brischke1); A O Rapp1); M Hasan2) ; R Despot2) 1) Leibniz University Hannover (LUH), Faculty of Architecture and Landscape Sciences

Institute of Vocational Sciences in the Building Trade 2) University of Zagreb, Faculty of Forestry, Wood Technology department

IRG / WP 10-20441 41th Annual Meeting Biarritz, France, 9-13 May 2010

Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences

Impact of climate change on wood deterioration – cultural heritage 1


Impact of climate change on wood deterioration Challenges and solutions for cultural heritage and modern structures C Brischke1); A O Rapp1); M Hasan2) ; R Despot2)

Part 2: How to cope with increased decay hazard in monuments? 1) Leibniz Practical recent of Landscape Echo Pavilion, University example: Hannover (LUH), Faculty restoration of Architecture and Sciences Vocational Sciences in the Building Trade of Croatia built in Institute 1843,ofclass listed cultural monument 2) University of Zagreb, Faculty of Forestry, Wood Technology department

Part 1: How does global warming influence decay in hazard class 3? Mathematical modeling for 5 different sites in Europe: IRG / WP 10-20441 Bordeaux, Freiburg, Portsmouth, Uppsala, Zagreb 41th Annual Meeting based on real fieldBiarritz, data from 28 exposure sites in EU France, 9-13 May 2010 Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences



Introduction (1) Chemists and biologists know: Increase in temperature → increases the speed of a reaction However in the real life it’s not at all that simple: • Many interactions e.g. temperature, MC, type of decay • Non linear behaviour: small changes can decide between “no attack” or “attack” • Limit states are important, Ross Gobakken introduced the CIC (critical in situ conditions), Brischke: “material climate” Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences



Introduction (2) 28 field trails spread over Europe in different climates for 5 - 8 years, • above ground = HC 3 • recording of climatic data • recording of wood MC and temperature • annual assessment of decay progress → Decay modelling = service life prediction: IRG/WP 10-20439 → Modelling the influence of global warming on decay for historic buildings Fungi have no preference, neither for ordinary nor for listed historic buildings → the same physiological rules of decay apply for both → data from historic buildings can be used to model service life of recent wooden structures and vice versa, as done in our study Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences



Methods Field trials and data logging




Location of 28 exposure sites 1

15

Germany

14

2 France

19 20

3

6

11

54

16 17 18

21

22 24 23 25

7 12

Switzerland 13

8

9

10

Different climate: 4 m to 1500 m elevation sea climate to mountain climate 3.3°C to 13.0°C average year temperature 500 mm to 2000 mm annual precipitation predominant winter to summer precipitation




Recording of weather data at site




Double layer test, HC 3

Scots pine sapwood Douglas fir heartwood




Data logging: wood MC + temp




Data logging: wood MC + temp

Conductive epoxy


Isolating epoxy

Polyamid coated stainless steel cables



Data logging: MC curves

65

Resistance in 10 x log Ohm

ha1

ha2

ha3

hsa1

hsa2

hsa3

60

mc 25%

55 33% 50 50% 45

40 1.2

1.3

1.4

1.5

1.6 1.7 YearDatum 2001


1.8

1.9

1.10

1.11



Data logging: wood temperature

Wood temperature in °C

50 45

Ps. menziesii

40

Pinus sylvestris

35 30

Pinus sylvestris shadow

25 20 15 10 5 0 -5 -10 -15 Dez. 01

Jan. 02

Feb. 02

Mrz. 02

Apr. 02

Mai. 02


Jun. 02

Jul. 02

Aug. 02

Sep. 02

Okt. 02



Annual decay assessment (1)




Methods Modelling by using dose-response functions dose → response wood MC → decay wood temp

}




Assumptions

It is assumed that • decay is the response on a dose, that • is a combination of a MC-induced component and a temperature induced component, • can be cumulated over the respective exposure intervals, and • can be correlated with the decay ratings in form of the response. Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences



Computer optimised dose functions

MC and temperature induced component Æ daily dose Daily dose = f (dMC ; dT) If T < 0°C then 0 Dose

Max daily dose = 1

If MC < 25% then 0

More details in IRG/WP 10-20439

1,0

0,8

0,6 ddMC MC = daily moisture induced dose ddT T = daily temperature induced dose

0,4

∑ daily dose = cumulated dose 0,2

0,0 0

10

20

30

40

50 60 MC [%], Tav [°C]


70

80

90

100



Accumulated daily dose = Total dose

Total dose [-]

Pine sapwood 900 800 700

Bordeaux Freiburg Portsmouth Zagreb

600

Uppsala

500 400 300

Slope = Total dose per time Dannual = Dose per year

200 100 0 10.02

04.03

10.03

04.04

10.04

04.05

10.05

04.06

10.06

04.07

10.07

Date Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences


Dose – response function


Mean decay rating [0-4]

Dose-response function for pine sapwood and Douglas fir heartwood 4

3

2

y = 4*EXP*(-EXP(1.7716-(0.0032*x))) R² = 0.901

1

0 0

200

400

600

800

1000

1200

1400

Total doseDose D



Critical dose


Mean decay rating [0-4]

Dose-response function for pine sapwood and Douglas fir heartwood 4

3

Limit state = end of SL 2

y = 4*EXP*(-EXP(1.7716-(0.0032*x))) R² = 0.901

1

0 0

1000 670 800 cumulated dose Dose critical dose = DDcrit Expected service life in years = 670 / Dannual 200

400

600


1200

1400



Five different sites exemplarily chosen Test site Height above sea level [m] Average air temperature [°C] Sum of precipitation [mm] Begin of exposure End of exposure 1

)average of 2000-2006 average of 2002-2006 3) average of 2000-2005 2)

Uppsala1) Sweden 7 6.8 579 05/2001 09/2008

cold winters cold summers

Portsmouth2) UK 1 11.6 667 04/2001 09/2008

mild maritime climat


Freiburg3) Germany 302 12.1 911 07/2000 09/2008 wet warm summers

Bordeaux1) France 4 14.0 798 01/2001 09/2008

Zagreb3) Croatia 123 10.7 910 08/2002 10/2008

dry warm summers

hot summers cold winters



Boundary conditions for warming

We took the real daily field data from Bordeaux, Freiburg, Portsmouth, Uppsala Zabreb, and added 0°, 1°, 2° or 3° K to each day then computed the total Dose and estimated service life ESL




Boundary conditions for warming

We took the real daily field data from Bordeaux, Freiburg, Portsmouth, Uppsala Zabreb, and added 0°, 1°, 2° or 3° K to each day then computed the total Dose and estimated service life ESL

It was assumed: • RH and MC was not affected, (just “global warming”) • Homogenous increase in temperature over the whole day • air-temperature = wood-temperature




Results



Scots pine ESL


5%

Estimated service life [a]

Why?

-2

6 5

-13 %

4 3 2 1 0

Uppsala

Portsmouth

Freiburg

Bordeaux

Zagreb

0

5,5

4,2

3,9

4,0

4,9

+1° K

4,9

4,0

3,7

3,8

4,6

+2° K

4,5

3,8

3,5

3,6

4,3

+3° K

4,1

3,6

3,3

3,5

4,0




Total dose over time pine sapwood

Total dose [-] 900 800 700

In Bordeaux temp is not limiting but dryness in some summers

Bordeaux

600 Uppsala

500 400

In Uppsala low winter temp. is the limiting factor

300 200 100 0 10.02

What if winter temp rises? → 04.03

10.03

04.04

10.04

04.05

10.05

04.06

10.06

04.07

10.07



Scots pine ESL


Warming leads to stronger decay response in colder climates 5%


-2

6 5

same level

-13 %

4 3 2 1 0

Uppsala

Portsmouth

Freiburg

Bordeaux

Zagreb

0

5,5

4,2

3,9

4,0

4,9

+1° K

4,9

4,0

3,7

3,8

4,6

+2° K

4,5

3,8

3,5

3,6

4,3

+3° K

4,1

3,6

3,3

3,5

4,0




Douglas Fir ESL

20


18 16

Why is Bordeaux NOT same

14 12 10 8 6 4 2 0

Uppsala

Portsmouth

Freiburg

Bordeaux

Zagreb

0

14,8

10,9

9,1

19,2

17,3

+1° K

12,3

10,1

8,2

17,2

15,3

+2° K

10,5

9,3

7,5

15,7

13,6

+3° K

9,3

8,7

7,0

14,5

12,3




Total dose over time Douglas fir

Total dose [-] 900 800 700 600 500

In Bordeaux dryness in summers (low MC) is limiting decay Douglas is only enough wet for decay during the rainy wintertime Freiburg site is all year wet enough even for the slowly water uptaking Douglas fir (site is surrounded by a humid forest)

400

Freiburg

300 200 Bordeaux

100 0 10.02

04.03

10.03

04.04

10.04

04.05

10.05

04.06

10.06

04.07

10.07



Douglas Fir ESL


Strong response in Bordeaux since decay season there is the wet winter Warming leads to strongest decay response in coldest climates Uppsala -2

20

5%

16

-3 8%


18

14 12 10 8 6 4 2 0

Uppsala

Portsmouth

Freiburg

Bordeaux

Zagreb

0

14,8

10,9

9,1

19,2

17,3

+1° K

12,3

10,1

8,2

17,2

15,3

+2° K

10,5

9,3

7,5

15,7

13,6

+3° K

9,3

8,7

7,0

14,5

12,3




Conclusion on warming

• 13-25% shorter service life expected in pine sap at warming of +3 K • 20-38% shorter service life expected in Douglas fir at warming of +3 K • Strongest influence if temperature is the limiting decay factor: e.g. when it is the whole year relatively cold (Uppsala) or when it is only wet enough for decay in the cold season (Bordeaux) • Global warming will increase decay and shorten service life • Amount of reduction depends on how strongly temperature is the limiting decay factor e.g. on interaction with course of MC • Amount of reduction depends on the, construction, wood species, climate • Interdisciplinary work is necessary with climatologists Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences



Structure

Impact of climate change on wood deterioration Challenges and solutions for cultural heritage and modern structures C Brischke1); A O Rapp1); M Hasan2) ; R Despot2)

Part 2: How to cope with increased decay hazard in monuments? 1) Leibniz Practical recent of Landscape Echo Pavilion, University example: Hannover (LUH), Faculty restoration of Architecture and Sciences Vocational Sciences in the Building Trade of Croatia built in Institute 1843,ofclass listed cultural monument 2) University of Zagreb, Faculty of Forestry, Wood Technology department

Part 1: How does global warming influence decay in hazard class 3? Mathematical modeling for 5 different sites in Europe: IRG / WP 10-20441 Bordeaux, Freiburg, Portsmouth, Uppsala, Zagreb 41th Annual Meeting based on real fieldBiarritz, data from 28 exposure sites in EU France, 9-13 May 2010 Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences



Echo pavilion in Maksimir Park

Designed by Franz Schücht, built in 1843 in Zagreb, Croatia, 1964 class listed

12 12




Lower part of the poles

Sever damage by brown rot, Gleophyllum abietinum and soft rot attacked the silver fir (Abies alba) and spruce (Picea abies) poles




Distribution of decay and MC

• It was necessary to restore the pavilion several times • Last restoration in 2000, Forest Faculty of University of Zagreb as consultant • Our colleague Prof. Radovan Despot measured in 2000 0,5 m above ground

1,2 m above ground

• Correlation of MC and decay, as expected • Lower part: more wet and more decay (splash water area) • North side more wet and more decay then south side Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences



Dilemma in conservation

• Listed monuments have to be conserved as original as possible: - keep the maximum amount of original substance - if replacement then use the same design, materials, techniques • What to do with faulty design? - in case of a safety problem it’s clear: make it save! - otherwise keep the historic (faulty) design to document it ? • Replacement of failing components in short intervals? Budget ! - improve (= change) the construction completely to save money? - keep the principle construction but extend the service life by using different materials plus wood preservatives? Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences



Material changes

• Tosan’s bases + bases: spruce → Slavonian Oak Q. pendunculata • Poles: silver fir + spruce → Larch heartwood • Poles single pieces → Recorcin glue compounds (less cracking)




Material changes

• Tosan’s bases + bases: spruce → Slavonian Oak Q. pendunculata • Poles: silver fir + spruce → Larch heartwood • Poles single pieces → Recorcin glue compounds (less cracking) • Poles and the lower parts of walls → Tebuconazole brushing → Boron pills → Water repellent treatment • Solvent based alkyd coating system Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences



Dilemma in conservation

• Listed monuments have to be conserved as original as possible: - keep the maximum amount of original substance - if replacement then use the same design, materials, techniques • What to do with faulty design? - in case of a safety problem it’s clear: make it save! - otherwise keep the historic (faulty) design to document it ? roof - install a monitoring system and act when necessary • Replacement of failing components in short intervals? Budget ! - improve (= change) the construction completely to save money? - keep the principle construction but extend the service life by using different materials plus wood preservatives? Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences



The roof problem




The roof problem

• Connection of the little top pillars to the roof sheeting • Sealant should prevent water from running into the roof




Decision to install a monitoring system

A




Installation of a MC data logger

A




No revision opening in the ceiling

A




On-wall system was allowed

A




On-wall system not very obtrusive

A




Perspective after restoration




Reading out of the data




Course of MC Course of MC

MC [%] 30

Measurement point 1 Measurement point 2

28

Measurement point 3

26

MC = 25%

24 22 20 18 16 14 12 05.02

09.02

02.03

07.03

12.03

05.04

10.04 03.05 Date


08.05

01.06

06.06

11.06

04.07



Conclusion

• Data logger is delivering daily MC data for more than 5 years • Measuring point 1, located at the lowest point, showed the highest MC corresponding with precipitation peaks • Strong indication that rain is leaking through the roof, running down the beam and accumulating at the lowest point • Critical MC limit of 25% was finally exceeded = clear signal to do the maintenance work of resealing of the roof NOW (!) • The early warning system proved to be feasible and saved costs by preventing lager damage and lager repairs. Andreas Rapp - Leibniz University Hannover - Faculty of Architecture and Landscape Sciences



Thank you for your attention! and all partners supporting us with the „32 sites“-project!




Accumulated daily dose = Total dose

Total dose [-]

Pine sapwood 900 800 700

Bordeaux Freiburg Portsmouth Zagreb

600

Uppsala

500 400 300 200 100 0 10.02

04.03

10.03

04.04

10.04

04.05

10.05

04.06

10.06

04.07

10.07




Douglas fir total dose over time

Total dose [-] 900 800 700

Freiburg

Slope = Dannual

Portsmouth Uppsala Zagreb

600

Bordeaux

500 400 300 200 100 0 10.02

04.03

10.03

04.04

10.04

04.05

10.05

04.06

10.06

04.07

10.07

