Development of conservation compatible new materials for envelope retrofitting of historic buildings

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1 Development of conservation compatible new materials for envelope retrofitting of historic buildings Carsten Hermann, Senior Technical Officer, Historic Scotland Glasgow is one of seven EFFESUS case study cities - Image Postdlf

2 EFFESUS researching energy efficiency of historic districts European FP7 project with 23 partners running from 2012 to 2016 Historic Scotland executive agency of the Scottish Government Scotland s national body concerned with the historic environment designating and protecting historic places, including listing of buildings and scheduling of monuments managing 345 historic buildings in state care, including conservation, interpretation, making accessible conducting conservation research, from conservation techniques to energy efficiency retrofit

3 Development of conservation compatible new materials for envelope retrofitting of historic buildings of historic buildings Retrofitting of building envelopes Historic buildings Building conservation New materials developed for masonry construction Insulating lime mortars Aerogel cavity-fill insulation Radiant selective coatings

4 Retrofitting building envelopes Envelopes are the fabric which protects building occupants and content from the outdoor climate. Envelopes provide shelter from wind and rain and help to create a suitable indoor climate. To reduce heat flow, envelopes can be retrofitted to improve airtightness thermal resistance

5 Historic buildings are of significance to present and future generations are of aesthetic, historic, scientific, social or spiritual value

6 Historic urban district Significant grouping of old buildings, built before 1945 and representative of the period of their construction or history Visby, Sweden, is an EFFESUS case study city Buildings do not necessarily have to be protected by heritage legislation. The envelopes of older historic buildings will have a moisture performance very different to that of today s construction. This matters when retrofitting building envelopes thermally as heat and moisture transport are coupled phenomena.

7 Building conservation Conservation is the management of historic building in ways which do not damage their significance. The best protection for historic buildings is often continued use. Conservation is not about preventing change per se, but about preventing change that damages significance. Conservation is based on the following principles: retain appearance of building fabric, where significant retain materiality of building fabric, where significant prevent deterioration of building fabric, or at least decelerate it ensure reversibility of any interventions or treatment

8 Development of new materials by EFFESUS Insulating lime mortar for use externally as render and internally as plaster Aerogel cavity-fill insulation insulating fibres for injection in cavities behind internal wall finishes Radiant selective coating for use on external surface to absorb and reflect infrared radiation

9 Insulating lime mortar Lead partner Development aim lime-based mortar for internal and external use generally suitable for substrates found in historic construction: porous permeable to moisture low elastic modulus accommodates small-scale movement compares to existing mortars better thermal performance λ-value < 0.08 W/(m K) not more costly

10 Insulating lime mortar Initial research Binder natural hydraulic limes (NHL) are generally used in building conservation NHL 5 achieves good strength development to bind a high ratio of an insulating filler Insulating fillers most mineral granulates λ-value no better than 0.08 W/(m K) aerogel particles too fragile for mixing and to resist impact damage cork λ-value no better than 0.1 W/(m K) expanded polystyrene (EPS) good, proven thermal performance, stable beads, variety of sizes

11 Insulating lime mortar Product development Material 80 vol. % EPS filler additional additives Application hand- or spray applied needs finishing lime mortar coat needs preparation lime mortar coat where substrates cannot be cleaned sufficiently Practicalities drying time of 7 days, due to substantial thickness no additional costs compared to conventional mortar

12 Insulating lime mortar Testing preparation

13 Insulating lime mortar Testing set-up

14 Insulating lime mortar Equipment for advanced moisture monitoring

15 Insulating lime mortar Equipment Thermal performance advanced moisture monitoring Christmas break Temperature Mortar impedance on limestone wall and brick wall

16 Insulating lime mortar Product performance Thermal performance λ-value W/(m K) Density ca. 300 kg/m 3 Strength after 90 days of curing Compressive strength 0.28 N/mm 2 Flexural strength 0.22 N/mm 2 Case study Benediktbeuern, Germany Testing of the new insulating line mortar as render on historic stone masonry

17 Aerogel cavity-fill insulation Lead partner Development aim aerogel insulation to fill cavities behind existing wall finishes historical lime plaster on timber laths retrofit plasterboard dry-lining compares to conventional cavity-fill insulation better thermal performance λ-value < W/(m K) not much more costly

18 Aerogel cavity-fill insulation Product development from monolithic aerogel fragile aerogel granulate, requiring stabilisation thermal resistance to be outstandingly high high costly and energy-intensive in production from aerogel blanket insulation polystyrene mesh fabric, impregnated with aerogel made from new, recycled or waste aerogel blankets thermal resistance better than conventional cavityfill insulation low cost if made from recycled or waste material

19 Aerogel cavity-fill insulation Material delivered for testing

20 Aerogel cavity-fill insulation Equipment used for injection of material

21 Aerogel cavity-fill insulation Material in test box for conductivity measurement

22 Aerogel cavity-fill insulation Thermal conductivity of fibres as delivered and after injection

23 Aerogel cavity-fill insulation Product performance Thermal performance λ-value down to W/(m K) Moisture performance vapour permeable & highly hygrophobic water absorption of kg/m 3 well below requirement of < 1 kg/m 3 Practical issues Loose fill should be reversible Dusting during handling health issue Case study Glasgow, United Kingdom Testing of fibrous aerogel cavity-fill insulation, installed behind various internal wall finishes

24 Radiant selective coating Lead partner Development aim focusing on infrared radiation coating for external surface application on masonry substrates to reduce heat transfer by both conduction and radiation minimal visual impact cost effective

25 Radiant selective coating Matrix and additive A. Coating matrices 1. based on sol-gel process, using silicon alkoxide precursors 2. ethanol- or water-based solution Infrared-effecting nanoparticles A. infrared absorbing coating absorbs most of the heat radiation acting thereby as a cyclic heat buffer B. infrared reflecting coating repels most of the heat radiation thus avoiding the heat transfer to substrate B.

26 Radiant selective coating Coatings and test substrates Ca Si C Al Fe Mg coating 1 X coating 2 X Istanbul stone X Villamayor sandstone X X Markina limestone X clay brick X X X X X lime mortar X

27 Radiant selective coating Performance assessment Reflectance by wavelength on lime mortar

28 Radiant selective coating Performance assessment Surface temperatures on brick test wall

29 Radiant selective coating Reversibility issues Neither of the radiant selective coatings is reversible on its own I. Tylose MH Reversible primer is required to separate coating from substrate I. Methylcellulose Tylose MH 300 P2 plasma-consistency substance II. Paraloid B-72 thermoplastic resin II. Paraloid

30 Radiant selective coating Removal assessment Application with Methylcellulose primer, removal with water and brushing coatings are not fully removable, regardless substrates tested Application with Paraloid primer, removal with acetone coating 1 is removable from calcium stones, but not fully removable from silica stones coating 2 is not fully removable regardless of substrate tested

31 Radiant selective coating Performance testing continues including testing of water absorption by capillary action material durability installation practicalities reversibility in practice Case study in Istanbul, Turkey Testing of radiant selective coatings, applied to historical stone substrates

32 Insulating lime mortar Aerogel insulation Radiant coatings Material testing Material installations

33 Thank you for listening Santiago de Compostela in Spain is an EFFESUS case study city Carsten Hermann Image copyright Turismo de Santiago The EFFESUS project has received funding from the European Union s Seventh Framework Programme for research, technological development and demonstration through grant agreement no This presentation reflects only the author s view, and the European Union is not liable for any use that may be made of the information contained.