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Comparison of different interior insulation materials
A. Bishara1, R. Plagge2
1 Technical university of Dresden, Institute of climatology, Germany, 3encult project, [email protected]
2 Technical university of Dresden, Institute of climatology, Germany, 3encult project, [email protected]
ABSTRACT
A wide range of perspectives is offered by the
opportunity to improve insulation standards of
historically listed building through internal insulation
and at the same time increase thermal comfort. On
the one hand, thermal renovation contributes in a
significant way to achieve the Kyoto-target. On the
other hand, insulation leads to an increase of thermal
comfort and therefore to an increase in the values of
historical buildings, and the attractiveness of the
living environment will increase as well. Interior
insulation offers in many cases the only appropriate
way to improve thermal insulation standards.
External insulation becomes impracticable due to
aesthetic aspects such as valuable stucco or brick
facades elements. Also, technical requirements such
as limiting distances or consisting frontage do not
allow for external insulation. for example, internal
insulation can be advantageous in temporarily
occupied rooms (meeting rooms, churches, schools,
banquet halls, etc.) where significantly faster energy-
efficient heating will be guaranteed [1].
Keywords
Thermal insulation system, internal insulation,
hygrothermal simulation, diffusion brake, historical
building, condensation, diffusion-open, capillary active.
1. Thermal insulation systems for internal
insulation
The use of interior insulation systems has been
structurally studied for over 20 years in the course of
attempted thermal renovation of our monuments. In this
context, particular attention is given to the expected
moisture accumulation in the walls’ cross section. There
are two principal possibilities to confront this moisture
problem depending on the way internal insulation is
executed:
1.1 Diffusion brake interior insulation:
The vapor diffusion flux into the wall is disabled by this
interior insulation system. Usually, vapor barrier-foils,
dense interior plaster, or approximate diffusion-proof
insulating foams are used. As a positive result should be
considered, condensation inside the structural element
should be avoided. But otherwise the negative impact is
an obstacle for dehydration processes, e.g., wind-driven
rain. Even design quality for component connections,
penetrations and deformations, (for instance beam heads
of wood beam ceilings) is required, which is very
difficult to realize [2].
1.2 Diffusion-open, capillary-active interior
insulation systems:
These systems allow vapor diffusion into the walls,
buffer the resulting moisture and remove the liquefaction
from the condensation zone back inside [3, 4]. The
moisture load of the wall is therefore considerably
reduced. The hygroscopic storage capacity of a
diffusion-open, capillary-active interior insulation system
buffers humidity peaks of indoor air and regulates the
indoor climate. The capillary action ensures that
moisture is distributed rapidly and widely inside the
insulation during the winter period. This accelerates the
drying process and improves the effect of the insulation.
Crucial for the functioning and performance of the
internal insulation is the interplay between moisture
buffering, vapor and liquid water transport. Moisture is
buffered and transported in the hygroscopic and also in
the over-hygroscopic range. Therefore, an assessment of
internal insulation requires the exact knowledge of these
variables and needs more sophisticated measurements
than usual. The following figure 1 shows the principle of
capillary-active inner insulation.
Abbildung 1. Wirkprinzip der kapillaraktiven
Inside outside
Water vapor
Diffusion-open, capillary-active interior insulation
Water content
Condensate level lies on the
cold side of the insulation
High drying potential
Good thermal insulation
Good moisture buffering
Mold resistance
Faster redistribution of the condensate by capillary
Faster evaporation
Reduction of local moisture
Figure 1: Operating principle of capillary- active inner
insulation: Due to the existing temperature difference
between inner and outer wall, water vapor diffuses
into the construction.
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At the point where the dew point is reached, water vapor
condenses and accumulates in the pores of the insulation
material. The insulation material transports the
condensation back to the surface because of its inward
directed capillary forces and the ability to conduct water
in its pores [5, 6]. The water is discharged from the
surface into the room. In the last 20 years, numerous
insulation systems have been developed and optimized
for interior insulation use. The development objective for
diffusion retarding systems is the reduction of the
insulation value and the improvement of the durability of
foil systems. Multi-functionality is the central
development goal for diffusion-open, capillary-active
systems. This requires an extensive development effort.
The improvement of the insulation value, the humidity
regulation, the integration of fire protection functions,
the soundproofing, and also the coupling to existing
structures is crucial for the structure. This multi-
functionality leads to an optimization process, so that
different interior insulation systems can be used wisely,
depending on the requirements of each interior insulation
[7].
Abbildung 2. Beispiele für unterschiedliche Dämmstoffe, die als Innendämm
Calcium silicate Mineral foam Mineral fiber Perlite
Foam glass Wood fiber Cellulose PUR
Figure 2: Examples of various insulation materials that
are used as interior insulation.
Figure 3: Product development at the IBK R & D lab.
In collaboration with a number of manufacturers of
building materials, the phases of material development
are running through several times until a suitable product
is optimized. Subsequently, the construction
development and market integration is done through test
houses and applications [8].
tretretre
Pore volume distribution Sorption isotherm Water retention
Liquid water lead Water vapor diffusion Thermal conductivity
Figure 4: Hygrothermal material functions of product
variants. E.g. the product development of calcium
silicate board of building material manufacturer
Calsitherm (the blue curve corresponds to the
optimized product).
1.3 Optimization cycle
Phase 1: The manufacturer of building materials
establishes appropriate product variants for interior
insulation. All components of the system are considered
here (variation of material components and additives,
manufacturing processes, etc.)
Phase 2: Measurement of hygrothermal material
parameters of different product variants with modified
properties. (Use of modern technologies to detect hygric
and thermal properties, which provide realistic material
functions in conjunction with a physical material model.)
Phase 3: Use of the material functions in the numerical
simulation and analysis of selected structural details. The
comparison of product variants allows statements about
the progress of material development. (Benchmark tests)
For future direction of material development, the results
of laboratory tests and numerical simulations will be
made available again to the manufacturers of the
building materials. Positive development steps then
follow the results. This material optimization cycle is
repeated until the adjustment of the aforementioned
material parameters reaches an optimum.
1.4 Product testing phases:
Phase 4: In this phase, the optimized product is tested
experimentally. These experiments serve to verify
material components and construction and provide the
verification of the functionality of the interior insulation
system. (Construction development and construction
testing).
Phase 5: The interior insulation system is used in a test
house after the end of the development phase (market
integration). The functionality and feasibility of the
insulation system is tested on location under real
conditions. (Measurement of hygrothermal conditions
with suitable sensors at selected positions in the
construction: temperature, relative humidity, material
moisture, etc., as well as the climatic conditions, air
temperature, relative humidity, radiation, rain, etc.,
Pore Volume Distribution Sorption isotherm Water retention
Liquid water lead Water vapor diffusion Thermal conductivity
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application training for engineers of building materials
manufacturer).
Humidity and temperature behavior of the studied test
houses are calculated in parallel with the software
DELPHIN by using the measured local climate data [9].
If the results of the simulation agree with the measured
data, then the running processes are reproduced by the
simulation software with its implemented physical
models. The material functions can then be used for
valuation of any wall constructions. A comprehensive
assessment of product safety can thus be met.
The last step is the application of the interior insulation
system for renovations, together with planning and
implementation.
2. Possibilities of hygrothermal evaluation
of wall constructions
The moisture protection must be considered a priority in
the renovation planning to ensure the permanent success
of an energetic building renovation. The following
should be considered as well: the formation of
condensation, rain, ascending humidity and introduced
building moisture and thermal bridges of some
construction. Another important aspect concerns the
compatibility of interior insulation and underground. For
an interior insulation system to become functional,
multiple layers have to be considered. The interior
insulation should be dimensioned so that the surface
condensation is avoided and the internal condensation is
limited, so that the drying potential obtained remains.
Calculation methods (e.g. COND) and simulation
programs (e.g. DELPHIN) are currently available as
planning tools for the planner. The use of these planning
tools requires knowledge of each required building
material parameters. Manufacturers are usually ready to
allow the determination of not yet existing parameters for
their new materials. For old building materials,
appropriate databases (e.g. MASEA) are available.
3. Comparison of interior insulation
systems based on practical examples
Sustainable functioning of the construction has the
highest priority of the energy-efficient renovations of the
listed buildings. The protection against moisture is the
first priority, followed by heat protection. Some
constructions are very sensitive; therefore, scientific
monitoring of energy-efficient renovation would be
appropriate.
3.1 Practical example: Wilhelminian house in
Dresden- New City
On the basis of the example of a wilhelminian house in
the Dresden-New City some measured and calculated
results are compared below (Figure 5). The typical
brickwork and sandstone veneer facade of the house is
listed. An increase of thermal protection can therefore
only be achieved by an inner insulation. In this case, a
calcium silicate board, capillary-active insulation is used
[10, 11]. The application of measurement techniques
enables the collection of important hygrothermal
performance parameters, such as the reduction of thermal
transmission losses and the control of the moisture
behavior. It also allows an assessment of energetic
renovation concepts. The measurement results are used
to validate the existing physical models in the simulation
program and verify the forecast possibility of
hygrothermal behavior.
Figure 5: Measuring arrangement in the wall section-
Wilhelminian house in Dresden- New City.
Figure 5 shows the position and arrangement of the
sensors: humidity and temperature sensors in the critical
zone, which were then installed in the condensate
potential level on the cold side of thermal insulation.
Additional humidity and temperature sensors detect the
near-wall microclimate on the outside of the wall with
interior insulation. The hygrothermal situations in the
wall cross-section are simulated numerically with the
program DELPHIN. These are considered as the locally
measured climate boundary conditions. The comparison
of the measurement data and the calculated temperatures
in the condensation zone agree sufficiently, as well as the
heat flux over the inner wall surface [12].
hh
Temperature, cold side, insulation
Heat flux, surface of the inner wall
Measured Calculated
Calculated Measured
Tem
per
atu
re °
C
Hea
t fl
ux
den
sity
in W
/m²
Figure 6: comparison of measured and calculated
(simulation software DELPHIN) time profiles of the
temperature in the condensation level (top), the heat flux
density on the inner wall surface (bottom).
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Figure 7: Comparison between measured and calculated
time profiles of relative humidity in the condensation
level.
By comparing of measured and calculated humidity, it is
noticed that the curves stand below 90% during the
entire time. The condensation range starts at 95%
relative humidity. It is assumed that in the considered
wall cross-section no condensation problems are
occurring based on an appropriate thickness of the
insulation and on the effect of the unsteady climate. With
increasing insulation thickness, the temperature drops on
the cold side of the insulation and the risk of
condensation rises.
3.2 Example of building: Hampel Warehouse
City in Potsdam
The four-story granary building was built in 1834/35 as a
timber frame construction and faced later with red
bricks, according to the design of Karl Hampel and
collaboration of Karl Friedrich Schinkel. After 10 years,
the building was enlarged at the corner areas. Each of the
last three window axes increased like a tower with an
extra floor. The remarkable design quality of this early
industrial building defines the extreme historic value of
this construction. The general description of the building
structure shows that the granary is a timber-framed
construction. The building was subsequently veneered
with red bricks to reduce driving rain entry into the
construction. Due to high driving rain, the façade has
been provided by Schinkel with a transparent water-
repellent paint. The enlargement at the corners has been
carried out with a grouting grout [13, 14, 15].
Figure 8: Warehouse city in Potsdam.
Figure 9: photo Schinkelspeicher, left old inner wall and
timber-framed construction; range of relative humidity
at the time of maximum moisture load: Uninsulated
center, right with 80mm clay insulation, cork insulation
with driving rain load (simulation).
During the planning of the interior insulation the specific
situation of the granary is taken into account. Hence, an
open-diffusion clay insulation and cork- diatomaceous
systems that is specially adapted to timber-framed
constructions is used. A 12mm thick moisture regulating
plaster over reed rabitz is applied inside. The energetic
evaluation of the whole construction assigns the chosen
buildup the EnEV-Standard 2007 minus 28% [16].
Figure 10: Interior insulation System (insulation loam
cork) Warehouse city in Potsdam.
Figure 9 demonstrate clearly the hygric situation for both
the existing and the insulated status. Insulated wall
structures are relatively dry close to the inner wall
surface, but the humidity increases towards the outside.
Because of the insulation, less heat gets into the
construction, whereby evaporation will be limited. If the
penetrated moisture cannot dry due to driving-rain load
during the cold period of the year, the risk of frost
damage for the historic brick increases. Therefore, the
rain entry is reduced through a surface treatment
according to Schinkel. A classical driving-rain protection
is not realizable using historic coatings. For this reason, a
hydrophobic impregnation with Silane- Siloxancreme for
the wall areas and a brick grouting grout for the tower
areas is adapted. Damaged joints have to be removed and
then grouted with a suitable, color coordinated joint
material. According to Heinze et. al. (2010), the
adaptation of the hydrophobic impregnation occurs
through adjusting the concentration of the hydrophobic
agent on each brick. The optimization goal is therefore
the diffusion openness with optimal drying capacity and
sufficient protection against driving-rain too [17].
Lo
cati
on
in
(m
m)
Lo
cati
on
in
(m
m)
Location in (mm)
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3.3 Example of building: Boelkespeicher
The Hafermagazin and the Fourageschuppen, which is
followed in the longitudinal axis, were designed by
architect Boelke and built in 1844[18, 19]. Architect
Boelke developed a gabled front in the classical style
with a regular clear, three zones building and inlaid
colored horizontal brick layers following the
Renaissance example. Both buildings are designed as an
ensemble, but they vary in volume and architectural
design. Magazine [Wharehouse] 5 (Hafermagazin) is a 4-
floor masonry building, with a ceiling and support
structure made of wood as well as a hipped roof.
Magazine [Wharehouse] 7 was built as a one-floor hall
with storage floor and gabled roof (20, 21].
Figure 11: Boelkspeicher in Potsdam.
Example brick ceiling basement
Construction
Figure 12: Detail ceiling construction basement/ground
floor outer wall of the architect Mrs. Mohr, 04.09.2008.
1 wooden Parquet, 2 floating cement screed, 3 aluminum
foil, 4 PE foam insulation, 5 Brick ceiling, 6 Calcium
silicate board, 7 masonry, 8 wood baseboard,9 perimeter
insulation, 10 sealing vertical
The proof of minimum thermal insulation, according to
DIN 4108 part 2 section 6.2 to avoid mould growth, for
this detail and as well as the simulation under real
climatic conditions are as follows [22].
Figure 13: temperature, surface temperature in [°C],
outer wall (56 cm) carried out with 6 cm calcium
silicate, boundary condition according to DIN 4108 part
2 section 6.2.
Figure 14: temperature, surface temperature in [°C],
outer wall (56 cm) carried out with 6 cm calcium
silicate, boundary condition with Potsdam climate.
The comparison of the graphs in figure 10 shows
disagreements between the standard defined climate and
the real climate conditions. The climate defined by the
standard at -10 °C over a period of 60 days does not
represent the real conditions in most cases. Via
numerical simulation, radiation (solar gains, long-wave
radiation) and precipitation (driving-rain, wind direction
and wind speed) are considered in the calculation. Figure
10 shows the real climate on a climatically unfavorable
day (January 2th). However, continuous information is
available for the whole calculation period (usually 3-5
years). This makes it possible to evaluate events in detail
at any time. It is possible to represent temperature, water
content, humidity, heat flow, moisture flow (liquid or
vapor) etc., because the calculation exports any status
variables. The humidity of the construction on April 22th
is shown in the following figure 15.
Inside
Outside
Basement
Inside
Outside
Basement
Ground floor
Basement
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Figure 15: Relative humidity on 22th April, boundary
condition according to Potsdam climate.
The area of floor beam bearing was calculated with edge
insulation of PS foam (d = 3 cm, contrary to build-up in
the construction detail, figure 9) to buffer different
expansions of the materials because of temperature as
well as ground movements. This represents a
constructive favorable and practical variant. A separating
layer of bituminous felt under the ceiling supports, which
is also not contained in detail, should also be
[is]incorporated. The field of relative humidity in figure
11 shows that no damaging moisture occurs in the inner
sector. There is higher relative humidity in the
condensate range between inner insulation and the brick
wall. However, the humidity can dry from the inside as
well as from the outside.
w
Rewerwer
Interior insulation
Interior insulation
Tem
pe
ratu
re in
[°C
]
Time in [a]
Figure 16: Shows the surface temperature (inside) of the
external wall (56 cm thick, at corner of wall connection)
in magazine 5, calculated with interior insulation 8 cm
and 10 cm calcium silicate, outdoor climate - Potsdam-
2nd und 3nd calculation year is presented with begin
January 1th.
err
rrrew
Interior insulation
Interior insulation
Re
lati
ve h
um
idly
in [
%]
Time in [a]
Figure 17: Relative humidity (inside) of the external wall
(56 cm thick, at corner of wall connection) in magazine
5, calculated with interior insulation 8 cm and 10 cm
calcium silicate, outdoor climate - Potsdam- 2nd und
3nd calculation year is presented with begin
January 1th. .
Figure 16 and 17 show temperature and humidity in the
corner of the wall connection for two different
thicknesses. The surface moisture is reduced during the
winter months with increasing thickness of the insulation.
4. Summary and Conclusion
Energy-efficient renovation does not have to conflict
with the respectful handling of our architectural cultural
heritage. The use of new material technologies in
historical monuments should be accompanied by an
advanced evaluation of renovation methods (e.g. by
building physics laboratory tests and application of
modern simulation tools). The historic preservation as
well as the hygric-energy performance of buildings
should be considered as well. Interior insulation of
historic buildings represents a challenge in several
aspects. Are new materials compatible with the existing
building and does it make any sense to postulate
insulation at all? What is the potential for energy
budgeting? But risks of damage also have to be
quantified. How are the utilization requirements in
accordance with protecting of the building envelope?
The energetic renovation and conversion offer a chance
to preserve valuable and culturally relevant buildings.
For this reason, it is required that the planning of interior
insulation agree with the construction. The examples
show that the following topics are significant for this
planning: selection and dimensioning of an internal
insulation, moisture load of the structure and driving-
rain protection, realization of construction details and
thermal bridges, and of course special cases such as salt
load of a construction. The use of special technologies
such as measurements and laboratory tests for building
diagnostic and material valuations as well as the
numerical simulation method for coupled moisture and
heat transfer processes are essential to implement this
planning. Ascending moisture, influence of gravity,
driving-rain and humidity under real climatic conditions
can then be considered. Complex geometric details such
as window connections or ceilings integration can also
be evaluated and optimized. Condensation ranges and
thermal bridges will be shown and thus construction
Inside
Outside
Basement
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damages are sustainably avoided. In this article, the
function principle of a capillary-active interior insulation
is explained. There are also specific material properties
and climatic boundary conditions which are required for
the assessment. The use of an interior insulation system
in a Construction in Dresden is also presented. For the
dimensioning of insulation and risk estimation, the
method of numerical simulation of coupled heat and
moisture transport processes under real climatic
conditions is used. It is shown in the present study that
capillary-active interior insulation has a great impact on
energy-saving renovation of buildings. In this context,
the knowledge of hygro-thermal functions of the building
materials is necessary. The numerical simulation method
offers a valuable contribution to dimension insulation as
well as risk assessment.
5. References
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feuchtetechnisches Verhalten von Baustoffen und
Bauprodukten. Bestimmung des Feuchtegehaltes durch
Trocknen bei erhöhter Temperatur (ISO 12570:2000);
Deutsche Fassung EN ISO 12570: 2000.
[2] DIN EN ISO 14683, Wärmebrücken im Hochbau .
Längenbezogener Wärmedurchgangskoeffizient.
Vereinfachte Verfahren und Anhaltswerte (ISO
14683:1999); Deutsche Fassung EN ISO 14683:1999.
[3] EN 12114, Wärmetechnisches Verhalten von Gebäuden .
Luftdurchlässigkeit von Bauteilen. Laborprüfverfahren;
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[4] WTA Fachwerkinstandsetzung nach WTA, Band 1,
Merkblätter 8-1 bis 8-9, Adeficatio-Verlag, Freiburg 2001
[5] Grunewald, J. 1997: Diffuser und konvektiver Stoff- und
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experimental investigation of Coupled Heat, Air,
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kulturvollen Entwicklung einer innerstädtischen
Industriebrache. In: SELPH2 – Im Herzen des
Europäischen Parlaments Green Hydrogen Initiative,
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von Gebäuden, ISBN 978-3-934681-92-7.
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Speicherstadt Potsdam – Schinkelspeicher,
Boelkespeicher und Persiusspeicher. In 1. Internationaler
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Wandkonstruktionen mit Wärmedämm-Verbundsystemen.
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Berlin 1998, S. 18-23.
[16] Lutz, P., R. Jenisch, H. Klopfer, H. Freymuth, L. Krampf
& K Petzod 1994: Lehrbuch der Bauphysik - Schall,
Wärme, Feuchte, Licht, Brand, Klima - 3. neub. Auflage
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[17] Heinze, P., R. Plagge & J. Engel 2010: Adaptive
hydrophobe Imprägnierung schlagregenbelasteter
Ziegelfassaden. Ed. H. Venzmer, Europäischer
Sanierungs-kalender 2010, S. 251-259.
[18] Plagge, R., J. Grunewald & P. Häupl 2006: Öko-
effiziente Renovierung von historischen Gebäuden. WTA
Almanach 2006 Bauinstandsetzen und Bauphysik -
Restauration and Building- Physics, WTA Publications -
ISBN 3-937066-05-5, 111-130.
[19] Plagge, R. 2005: Hygrothermal Characterization of
Building Materials. In Study of moisture movement in
building material and its simulation analysis, Seminar
Book of Kyoto University, Katsura Campus, Japan, 20-41.
[20] Plagge, R. 2011: Abstimmung zwischen Feuchtezustand,
Schlagregenschutz, Abtrocknung und Dämmzonzept am
Beispiel der Elbphilharmonie Hamburg. In Bauforschung
und Baupraxis. ISBN 978-3-86780-216-1, 313-322.
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diffusionsoffen und kapillar-aktiv. Informationsbrochüre,
Xella Technologie- und Forschungsgesellschaft mbH.
[22] DIN 4108-2-3-4-7, Wärmeschutz und Energie-Einsparung
in Gebäuden. Teil 2: Mindestanforderungen an den
Wärmeschutz.
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