Considerations about plastering

with aerogel from the viewpoint

of heritage preservation

Walter Niederberger, stv. Denkmalpfleger BL

Introduction

The function of built heritage

• witness of the history of the people

• irreplaceable source of information

• important public function

Introduction

New challenge:

Energy-saving renovation of historic buildings

• conservation means protection of the substance

• the substance accounts for the authenticity

• energy-saving

renovation must

meet requirements

Levels of protection

• historic buildings with integral protection

• buildings with protection of their appearance

Integrally protected buildings

Principles of conservation

• witnesses of history

• unique and cannot be reproduced

Integrally protected buildings

Protection and prevention

• construction measures must not interfere

with the historical value

• building standards may not be used

Integrally protected buildings

Six principles of conservation and restauration

• Conservation of the substance

• conservation means protection of the substance

• Age and uniqueness as a feature

• the uniqueness

is to be

preserved

Integrally protected buildings

Six principles of conservation and restauration

• Ability of repair and maintenance

• repairs are the guarantors of the survival

• traditional building materials and techniques

• Reversibility

• interventions

must be

carried out

with a high

degree of

reversibility

Integrally protected buildings

Six principles of conservation and restauration

• Adequacy and minimum intervention

• elements should not be replaced without necessity

• Addition instead of replacement

• addition should

always have

priority

Buildings with protection of

their appearance

• significance for the townscape

• witnesses of a cultural heritage

• important aspect:

renewal

Energy-saving renovation of

historic buildings

Earlier insulation measures

• only comfort mattered

• wooden wall

panelling

Energy-saving renovation of

historic buildings

Today's requirements

• reducing harmful emissions

• raising comfort

• reducing heating

costs

Historic buildings and energy

Integrally protected buildings

• listed buildings: about 2% of the building stock

• energy consumption: about 1%

Integrally protected buildings

Objectives, strategies

• conservation of the substance

• preservation of the appearance

Integrally protected buildings

Non-Structural measures to reduce

energy consumption

• non-structural measures: highest priority

• operational measures

Integrally protected buildings

Structural measures to reduce energy consumption

• insulation of: unheated roof space

• heated attic

• basement ceiling

• on the inside of

external walls

• external insulation

of parts with

ground contact

• increased thick-

ness of insulation

Buildings with protection of

their appearance

• appearance of the exterior is crucial

• no adverse effect to the historic appearance

of a building

Pilot project: the former mill

Introduction

• first project

• new high performance insulation plaster

• thin layer, like the existing plaster

• new product:

aerogel insulation

plaster

Pilot project: the former mill

The building and its history

• 14th century

• high gable walls

• plaster with Portland cement

Pilot project: the former mill

Energy concept

• best possible solution for lowest possible energy

consumption

• «Miniwatt»

• «Minifossil»

• «Minispace»

• «Minicar»

Pilot project: the former mill

Energetic rehabilitation measures:

• insulation of the outside

• new windows

• insulation of the floor of the unheated roof space

• insulation of the

basement ceiling

• insulation of the

inner window

reveal

Pilot project: the former mill

Energetic rehabilitation measures:

• installation of a ventilation system with heat recovery

• best household appliances

• change from oil to wood pellets

• restoration of

old heaters

• wood pellets

for heating the

water

Pilot project: the former mill

Requirements of the pilot project

• conservation rules apply

• no change of the appearance

• no replacement of historic plaster

• same thickness of

the plaster

• purely mineral

composition

• no loss of relevant

substance

Pilot project: the former mill

Implementation of the energetic concept and

considerations regarding preservation

• no insulation boards

• no conventional insulating plaster

• preservation of the

appearance

• comply with

heritage-friendly

materials

Pilot project: the former mill

Findings

• historical plaster: lime putty

• new plaster: seven different layers or steps

• roughcast

• insulating plaster

• undercoat stabilizer

• embedding mortar

• reinforcement fabric

• final coating layer

• topcoat of paint

Pilot project: the former mill

Findings

• purely mineral

• fabric: undesirable for historic monuments

• natural fibres or animal hairs: compatible

• historically accurate

appearance

• proved adequate

• energy consumption

cut by half

Conclusion

Energy-saving renovation of integrally

protected buildings

• not with integrally protected buildings

• loss of substance

• using historically

authentic material

composition

Conclusion

Energy-saving renovation of buildings with

protection of their appearance

• maintaining the appearance

• maintaining typical design features

Summary

• not on integrally protected buildings

• only on buildings with protection of their appearance

and non-protected buildings

• preservation of the appearance

• energy saving

Thank you for your attention