eps

1. Energy and Buildings 37 (2005) 77–86
State of the art in thermal insulation materials and
aims for future developments
A.M. Papadopoulos∗
Laboratory of Heat Transfer and Environmental Engineering, Department of Mechanical Engineering,
Aristotle University Thessaloniki, Box 483, 54124 Thessaloniki, Greece
Received 31 March 2004; received in revised form 15 May 2004; accepted 20 May 2004
Abstract
Insulation materials are the key tool in designing and constructing a energy thrifty buildings. This is demonstrated by the increasing
thicknesses used in buildings, which also reflects in the growing sales of the branch. The European market of insulation materials is
characterised by the domination of two groups of products inorganic fibrous materials and organic foamy materials. They all feature similar
performance in terms of insulating capabilities, but otherwise present significant differences. These are discussed in detail in the following
paper. Despite the fact that the thermal properties of the materials has not improved significantly of the last decade, a series of other features,
like reaction to fire and moisture or mechanical properties have improved, sometimes even at the cost of insulation abilities. Furthermore,
environmental and public health aspects play an increasing role, both in the search for ‘optimum’ materials for given applications, and in
the aims set by the industry for future developments. These aims, examined within the legislative and market framework, are discussed in
this paper, both as criteria for evaluating state of the art materials and as goals for future research developments.
© 2004 Elsevier B.V. All rights reserved.
Keywords: Thermal insulation materials; Inorganic fibrous; Organic foamy; Properties & performance
1. Introduction
Thirty years after the introduction of compulsory thermal
insulation in most European countries, insulation materials
form still the major tool for the improvement of a building’s
energy behaviour. The use of insulation materials has in-
creased, both in terms of buildings being insulated and in the
minimum values of insulation required by the national reg-
ulations. This degree of insulation necessary becomes clear
when considering the U-values foreseen in various Euro-
pean countries for the building envelope of presently built
residential buildings in Table 1. The evolution that has taken
place since the early 1970s becomes evident when consider-
ing the increase in the typical insulation thickness required
in European countries over the years. This is depicted for
walls and roofs in Figs. 1 and 2, respectively [1]. It is also
of interest to notice that whilst in some countries, mainly in
Northern Europe, the requirements have almost doubled dur-
ing this period, in others, like in Greece, the standards have
remained unaltered. It is also clear, that in order to achieve
∗ Tel.: +30-2310-996011; fax: +30-2310-996012.
E-mail address: agis@eng.auth.gr (A.M. Papadopoulos).
the tighter standards insulation materials have to improve
their features. This is even more the case, as requirements
have increased not only in terms of thermal properties, but
also with respect to indoor environmental quality and the en-
vironmental impact. The way in which insulation materials
correspond to this task is discussed in this paper.
Insulation materials are not independent energy produc-
tion or conservation systems, but part of the complex struc-
tural elements which form a building’s shell. In that sense,
they cannot be evaluated in the way, energy producing sys-
tems, like solar thermal systems or photovoltaics can, but
they have to be evaluated as an integral part of a building’s
design and construction. Furthermore, the quality of an in-
sulating material depends on its adaptability to national, re-
gional or even local building ways and traditions. In that
sense, materials that are wide-spread in specific regions are
rare in others, though, from the scientific point of view, any
material could be used instead of the other.
There are certainly very good perspectives for the other
materials, like perlite, foam glass and wood wool, focused
on specific applications, where high specifications are set
on certain mechanical properties, on sound insulation and
on humidity resistance, or where the initial cost factor is
less important than in average residential and commercial
0378-7788/$ – see front matter © 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.enbuild.2004.05.006

2. 78 A.M. Papadopoulos / Energy and Buildings 37 (2005) 77–86
Insulation thickness applicable in walls
0
50
100
150
200
250
Sweden
Finland
Denmark
Norway
Austria
Switzerland
France
Netherlands
Germany
Spain
England
Ireland
Italy
Belgium
Greece
Turkey
Country
Thickness[mm]
1982
1990
1995
1999
Fig. 1. Evolution of insulation thickness applicable in walls in Europe.
buildings. A further point of interest is the development
of the ‘alternative’ materials, like sheep and cotton wool,
and the ‘intelligent’ materials, like transparent insulation
and dynamic materials with temperature depending thermal
conductivity properties. Their stronger propagation on the
market is still by and large an issue of economics, fur-
ther development depending both on improvements in the
production processes and on achieving economies of scale.
At the same time, a series of new ‘ready to use’ build-
ing components was developed, applicable for specific con-
structions. As such one can mention prefabricated panels for
commercial and office buildings, prefabricated panels for
retrofitting insulation of residential buildings, etc. The per-
Insulation thickness applicable in roofs
0
50
100
150
200
250
300
350
400
450
Sweden
Finland
Norway
Denmark
France
Austria
England
Germany
Ireland
Switzerland
Netherlands
Belgium
Turkey
Spain
Italy
Greece
Country
Thickness[mm]
1982
1990
1995
1999
Fig. 2. Evolution of insulation thickness applicable in roofs in Europe.
formance of the insulating material itself in this products
(be it organic foamy or inorganic fibrous) remains the main
determinant of such a component’s energy behaviour. The
yardstick of their success, however, depends on criteria such
as adaptability, versatility, handling and cost.
2. Classification of insulation materials and the
European market
Insulating materials can be classified according to their
chemical or their physical structure. The most widely used
insulating materials can accordingly be classified as shown

3. A.M. Papadopoulos / Energy and Buildings 37 (2005) 77–86 79
Table 1
Typical U-values for the building envelope of presently built residential
buildings in various European countries
Roofs Outer walls Ground floors Windows
Austria 0.2–0.3 0.3–0.4 0.4–0.5 1.0–1.5
Belgium (Flanders) 0.4–0.5 0.5–0.6 0.6–0.6 1.5–2.5
Denmark 0.1–0.2 0.2–0.3 0.1–0.2 1.5–2.5
Finland 0.1–0.2 0.2–0.3 0.2–0.3 1.5–2.0
France 0.2–0.3 0.4–0.5 0.3–0.4 1.5–2.5
Germany 0.2–0.3 0.5–0.6 0.4–0.5 1.0–1.5
Greece 0,4–0,5 0,5–0,7 0,7–1,9 2,5–3,5
Ireland 0.1–0.2 0.2–0.3 0.2–0.3 1.5–2.5
Italy 0.3–0.4 0.4–0.5 0.4–0.5 2.5–3.5
Lithuania 0.1–0.2 0.2–0.3 0.2–0.3 1.5–2.5
Norway 0.1–0.2 0.2–0.3 0.1–0.2 1.0–1.5
Portugal 0.6–0.6 0.6–0.6 0.6–0.6 2.0–3.0
Russian Federation 0.1–0.4 0.1–0.2 0.1–0.4 1.5–3.5
Spain 0.6–0.6 0.6–0.6 0.6–0.6 2.5–3.5
Sweden 0.1–0.2 0.1–0.2 0.1–0.2 1.0–1.5
Switzerland 0.3–0.4 0.3–0.4 0.6–0.6 1.0–1.5
UK 0.1–0.2 0.3–0.4 0.2–0.3 1.5–2.5
The Netherlands 0.2–0.3 0.2–0.4 0.2–0.3 1.5–2.5
in Fig. 3. The European market of insulating materials is
characterised by the domination of two first two groups of
products, namely inorganic fibrous materials, glass wool and
stone wool, which account for 60% of the market, and or-
ganic foamy materials, expanded and extruded polystyrene
and to a lesser extent polyurethane, which account for some
27% of the market [2]. All other materials accounted for less
Fig. 3. Classification of the most used insulating materials.
than 13% together. As far as the producers are concerned,
there are some 250 companies providing the market; nine
of them accounted in 2003 for more than 55% of the total
annual production [2]. Through the 1990s production vol-
umes showed a steady increase, as the construction of new
and the rehabilitation of old buildings boomed, reaching a
value of approximately 3000 kt in the year 2001. The pre-
dictions for the decade 2000–2010 estimate an average an-
nual growth rate of more than 4% [2–4]. Inorganic fibrous
materials are expected to play the main role, with growth
rates of more than 5%, whilst organic foamy materials are
expected to annual show growth rates of some 2.5% [4].
Coming to examine the perspectives for the development
of the insulating materials, with respect to the market con-
ditions and the trends prevailing in the industry and for the
scope of this paper, it is considered as feasible to focus the
analysis on the following five main groups of materials [5,6].
Glass wool consists of quartz sand, dolomite, reso-
vit and limestone. Furthermore, adhesive materials and
water-repellent oils are added, in order to increase the
mechanical strength of the materials, though the use of
these elements must be kept within limits to achieve a high
fire-resistance.
Stone wool consists of the same basic materials as glass
wool. Its main differences concern the higher melting tem-
peratures during the production process and the different
size of the fibres. These differences make stone wool heav-
ier, with a higher melting point and hence better suited for
high temperature applications.

4. 80 A.M. Papadopoulos / Energy and Buildings 37 (2005) 77–86
Glass wool and stone wool form the mineral wool group,
which is used a single group for many of their properties,
according to CEN.
Expanded polystyrene consists of polymerised polystyrol
(1.5–2%) and air (98–98.5%). Pentane is used as a propellant
gas in the expansion process. Hexanbromcyclododecan is
used, to a percentage of 5–7%, to improve the fire-resistance
properties.
Extruded polystyrene is also based on polymerised
polystyrol. Carbon dioxide is used in a percentage of 3–7%,
as propellant gas and as fire-resistance additives are used to
1–6%, together with talcum powder and coloring elements.
Polyurethane foam is based on poly-isocyanic associa-
tions. The propellant gas used initially was R11, which was
forbidden in the late 1980s and was substituted by carbon
dioxide or pentane. This modification lead to an increase of
the thermal conductivity of polyurethane foam.
The main properties of these five materials, are discussed
in the following paragraph, together with qualitative data
and comments on all other commonly met materials.
3. Properties and performance of insulating materials
The properties of insulating materials are traditionally
subdivided into three main groups. There are the traditional
physical properties, which describe the material’s behaviour
in terms of density, mechanical strength, thermal insulation
ability, sound absorption, resistance to moisture and fire,
etc. These traditional physical properties are fairly easy to
determine and certify, as specific standards existed on na-
tional level for more than 30 years. In the meantime, there
are internationally applicable standards and directives like,
Table 2
Regulations on dust and man made vitreous fibres (2004)
Country Current regulations
Dust Mineral wool fibres
Austria Fine dust: 6 mg/m3 (yearly average), 12 mg/m3 (monthly average) Fibres: 0.5 F/ml
Belgium Total dust: 10 mg/m3
Denmark Inert respirable dust: 5 mg/m3, total inert dust: 10 mg/m3 Fibres: 1 F/ml (8 h TWA)
Finland Inert inorganic dust: 10 mg/m3 No official limit value: 1 F/cm3, this limit is used as
reference
France Total dust: 10 mg/m3 Respirable fibres: 1 F/ml
Germany Alveolar dust: 3 mg/m3, inhalable dust: 1 Qmg/m3
(from 1 April 2004)
Fibres classified as Carcinogen: 0.25 F/ml, non-classified
fibres: 3 mg/m3
Ireland Inhalable dust: 5 mg/m3 Airborne respirable fibres: 2 F/ml, superfine fibres: 1 F/ml
Italy Total dust: 10 mg/m3, respirable dust: 3 mg/m3 Glass fibres: 1 F/ml, ceramic fibres: 0.2 F/ml
The Netherlands Respirable dust: 5 mg/m3, general dust: 10 mg/m3 Respirable fibres (8 h TWA): 2 F/ml
Norway Inert respirable dust: 5 mg/m3, total inert dust: 10 mg/m3 Fibres: 1 F/ml
Poland Respirable dust: 1 mg/m3, total dust: 4 mg/m3 Respirable fibres: 2 F/ml
Spain Total dust: 10 mg/m3, respirable dust: 3 mg/m3 Fibres classified as Carcinogen: 1 F/ml
Sweden Respirable dust: 5 mg/m3, total dust: 10 mg/m3 Fibres: 1 F/ml
UK Inhalable dust: 5 mg/m3, total dust: 10 mg/m3 Airborne respirable fibres: 2 F/ml or gravimetric dust:
5 mg/m3, superfine fibres: 1 F/ml
EU DG social affairs: regulations under discussion
USA Respirable dust: 5 mg/m3, total nuisance dust: 10 mg/m3 Fibres: 1 F/ml
amongst other, the EN ISO 6946, EN 13162, EN 13163, EN
13164, BS 476, 89/106/EC [7–13].
Then there is a second group of less clearly stated, and
even less commonly accepted, criteria, dealing with the en-
vironmental impact of insulating materials. This group in-
cludes properties like the primary embodied energy, the gas
emissions for the production of the material, the use of ad-
ditives against biological impacts, the classification of their
treatment as waste, etc., their re-usability and recyclability
and the environmental impact of the material, based on the
Life Cycle Analysis approach according to ISO 14025-00.
The last one forms an internationally acceptable framework
for the environmental labelling [14]. Still, the properties
monitored are more difficult to compare and to assess, as
they can vary for the same type of material, according to
the location of the production, the primary energy resources
used, national environmental legislation, etc. [15]. Finally,
there is the group of properties dealing with public health,
during the production, the use and at the final stage of dis-
posal of the materials. This group includes properties like
dust and fibres emissions, biopersistence, toxicity in case of
fire, etc. [16,17]. The wide range of standards and maximum
prevailing concentration values currently allowed in Europe
can be seen in Table 2 [18]. However, as the health proper-
ties become more important, the establishment of commonly
accepted assessment methods and benchmarking values is
inevitably the next step in the process of European harmon-
isation.
In any case, when coming to evaluate the performance of
insulating materials and to set aims for their future devel-
opment, one cannot fail to observe that even the physical
properties of a single type of material vary significantly,
according to the specific structural application, which de-

5. A.M. Papadopoulos / Energy and Buildings 37 (2005) 77–86 81
termines the sort of the material that has to be used. Taking
a typical inorganic fibrous material, like stone wool, it can
feature a density of anything between 25 and 200 kg/m3,
with respectively varying thermal conductivity values, but
also sound insulation properties. It can be in the shape of
loose material, rollbatts, flexible or rigid slabs, with re-
spectively varying mechanical and physical properties. The
range of properties that occurs for each type of material
becomes evident, when considering the physical properties
for the five main types of materials mentioned earlier, which
are presented in Table 3 [19].
The insulating performance of insulation materials,
namely the thermal conductivity value [λ in W/m K] or
respectively the thermal transmittance coefficient [U in
W/m2 K] for composite materials, has remained fairly con-
stant over the last decade and can, from the aspect of
thermal transfer be judged as very satisfactory. This should
not mislead to the conclusion that contemporary materials
are at the same level with those used in 1990. There was
Table 3
Basic features of the commonly met insulating materials, current state of the art
Main physical features Material
Glass wool Stone wool Extruded polystyrene Expanded polystyrene Polyurethane foam
Density (kg/m3)
Minimum 13 30 20 18 30
Maximum 100 180 80 50 80
Thermal conductivity factor, λ (W/m K)
Minimum 0.030 0.033 0.025 0.029 0.020
Maximum 0.045 0.045 0.035 0.041 0.027
Temperature application range (◦C)
Minimum −100 −100 −60 −80 −50
Maximum 500 750 75 80 120
Resistance to vapour diffusion factor
Minimum <1 <1 80 25 50
Maximum 1 1 200 200 >100
Humidity assimilation rate (at 23 ◦C/80% RH)
Minimum <0.1 <0.1 <1a 5a 5a
Maximum 1 1.5
Reaction to fire class
Minimum A1 A1 B1 B1 B1
Maximum A2 A2 B2 B2 B2
Tensile strength (N/mm2)
Minimum 0.005a 0.30 0.15
Maximum 0.35 0.52
Ultimate tensile strength (N/mm2)
Minimum 0.00500 0.00012 0.09000
Maximum 0.01500 0.00750 0.22000
Sound absorption degree (at 125 Hz)
Minimum 0.10 0.05
Maximum 0.79 0.19
Sound absorption degree (at 1000 Hz)
Minimum 0.71 0.92
Maximum 0.97 0.99
a Mean values.
significant progress during this period, as a result of the
joint effort of academic and industrial research, focused on
the environmental and health aspects, which form the main
challenge for the ongoing decade 2000–2010. This becomes
more obvious when comparing the data of Table 4, which
presents what was determined, by a study carried out in
1996–1997 for the European Commission, as state of the art
in the mid-1990s [18], to the current state of the art, which
were presented in Table 3 and the state of the art features
in terms of environmental and health aspects of insulation
materials presented in Table 5.
The complexity of determining and assessing the envi-
ronmental properties of the materials becomes more evident
if one adopts a qualitative approach, like the one suggested
by the British Thermal Insulation Manufacturers and Sup-
pliers Association, which is depicted in Table 6 [20]. Still,
this quantitative approach may be of help in order to evalu-
ate and compare materials and also in order to set priorities
for future research.

6. 82A.M.Papadopoulos/EnergyandBuildings37(2005)77–86
Table 4
State of the art materials and properties in the mid-1990s [18]
Insulation type Conduct
(W/m K)
Where used How installed Resistance to (1 = excel., 2 = good, 3 = fair, 4 = poor) Environmental/health concerns
Water abs. Moisture damage Direct sun Fire
Fibreglass Batts, rolls 0.041 Wall, floor and
ceiling cavities
Fitted between
studs, joists or
rafters
2 1 1 2 Quite safe environmentally, some concern that
fibres may be carcinogenic
Fibreglass Loose, poured
or blown
0.041 Ceiling cavities Poured and fluffed
or blown by
machine
2 1 1 2 Quite safe environmentally, but greater health
concern with loose-fill fibreglass than fibreglass batts
Rock wool Batts, rolls 0.041 Wall, floor and
ceiling cavities
Fitted between
studs, joists or
rafters
2 1 1 1 Quite safe environmentally, some concern that
fibres may be carcinogenic
Rock wool Loose, poured
or blown
0.041 Ceiling cavities Poured and fluffed
or blown by
machine
2 1 1 1 Fibres may pose health risks
Dry cellulose id 0.078 id Blown by machine 4 4 2 3 Environmentally attractive, provides market for
recycled newspaper and cardboard
Wet spray cellulose id 0.09 Wall cavities Sprayed into open
cavities
4 3 2 3 See above
Perlite id 0.050 Hollow concrete
block
Poured 3 2 1 2 Very safe environmentally
Blown fibre with binder id 0.041 Wall and ceiling
cavities
Blown dry into
cavities faced with
mesh screening
Depends on
fibre used
Depends on
fibre used
Potyurethane (PUR) id 0.027 Wall and ceiling
cavities, roofs
Foamed into
cavities
1 1 4 4 Most urethane produced with HCFCs which deplete
stratospheric ozone, possible substitute blowing
agent but with decreased thermal properties
Polyurethane Rigid boards 0.030 Wall, ceiling, roofs Glued, nailed 1 1 4 4 See above
Expanded polystyrene (EPS) Rigid board 0.039 Wall, ceiling, roof Glued, nailed 3 2 4 4 Foam produced with pentane gas, may contribute
smog and ground level ozone
Extruded polystyrene (XPS) Rigid board 0.035 Foundations,
sub-slab, wall,
ceiling, roof
Glued, nailed 1 1 4 4 Produced with HCFC 142b which depletes
stratospheric ozone to some extent
Rigid fibreglass Rigid board 0.063 Foundation walls,
walls, roofs
Glued, nailed 2 1 1 2 Quite safe, may be some out-gassing of resins
used as binders

7. A.M. Papadopoulos / Energy and Buildings 37 (2005) 77–86 83
Table 5
State of the art environmental and health features
Material
Glass wool Stone wool Extruded
polystyrene
Expanded
polystyrene
Polyurethane foam
Biopersistence Exempteda Not applicable
Toxicity in case of fire Not applicable Depending on the propellant
and the additives—yes
Yes
Maximal exposure limits 3–10 mg/m3b None set
Use of CFCs, HCFCs, CO2 No Some producers still use
HCFCs (i.e. 142b/22,
134a, 152a, etc.), others
CO2
Waste disposal No particular burdens
or limitations occur
As a waste its
biopersistence is long,
hence it should not be
treated as common
demolition waste
Re-use and recycle Practically not re-usable, recyclable Re-usable recyclable, either for
building purposes or for lower
quality packaging material
It is not re-usable
or recyclable
Use of raw resources No hydrocarbons or other rare
resources are used
Hydrocarbons are used
Additives for protection
against biological impacts
No No Yes
Primary embodied energy (kW h/m3)
Minimum 90 110 85 151 15.8
Maximum 430 660 114 269 36.1
a According to IARC, since October 2001, that all mineral wool fibres are considered not classifiable as to carcinogenicity to humans (IARC group 3).
b According to national standards.
Table 6
Evaluation of insulation materials accorded to environmental criteria [20]
Material Environmental impact
Production Use Total
Polyurethane foam 5 0.75 5.75
Expanded polystyrene 5 0.25 5.25
PVC foam 5 1 6
Glass wool 3.5 1 4.5
Stone wool 3.5 1 4.5
Extruded polystyrene 5 0.25 5.25
Flax 0.25 0.25 0.5
Cotton 0.25 0.25 0.5
Wool 0.25 0 0.25
Cellulose 0.25 0 0.25
Cork 0.25 0.25 0.5
Foam glass 3 0 3
4. Comparative evaluation of state of the art materials
From the data presented so far it becomes obvious that
the evaluation of the performance of insulation materials is a
multicriteria problem, that has to be carried out with respect
to:
(a) their physical properties,
(b) their health and environmental properties,
(c) their applicability in specific building elements and
structural problems, and
(d) their cost, as a function of the above-mentioned param-
eters.
It is also clear that the evaluation has to be carried out
for a given thermal conductivity of the materials considered,
and as it is beyond any possible classification scheme to
indicate absolute criteria for all the parameters concerning
the evaluation of every single type or form of material, the
judgement should be based on:
(a) The evaluation of the materials applicable to achieve a
specific U-value in the construction.
(b) The evaluation of the materials’ improvement, either
compared to their current state of the art or compared
to the competitive materials that present the same ba-
sic energy performance and are applicable for the same
structural elements.
(c) The cost factor, not necessarily on absolute terms, but
as a ratio to the competitive materials.
Therefore, a material can be characterized as “state-of-the-
art” when one or more of its features are significantly better
than other materials [21]. Such a comparative evaluation is
presented in Table 7.
5. Aims for their future development
Considering the analysis discussed in the previous para-
graph, the target of research for future developments should

8. 84 A.M. Papadopoulos / Energy and Buildings 37 (2005) 77–86
Table7
Rankingofstateoftheartinsulationmaterials—basedonthepropertiesofaverage,commerciallyavailablematerials
InorganicfibrousOrganicfoamyOrganicfibrousInorganicfoamyOther
Glass
wool
Stone
wool
EPSXPSPUSheep
wool
Cotton
wool
CelluloseCoconut
fibres
PerliteFoam
glass
Gypsum
foam
Experimental
cork
Wood
wool
Thermalattributes᭺᭺᭺᭺+᭺᭺᭺᭺−᭺᭺᭺−
Moistureresistance᭺/+᭺/+᭺++᭺᭺᭺᭺++᭺᭺−
Pressureresistance−᭺/++++−−−−−+−/᭺++
Tensileresistance++᭺/+᭺᭺/+++᭺᭺᭺−/᭺᭺᭺/+−/᭺
Soundproofing++᭺−/᭺−/᭺+++᭺/+᭺/+−/᭺᭺᭺᭺/+
Reactiontofire++᭺᭺−/᭺᭺᭺᭺᭺++᭺᭺᭺
Resistanceatbiologicaldangers
(insects,fungus,etc.)
+++++᭺᭺᭺᭺+++᭺+
Emissionsduringproduction᭺/−᭺/−+++᭺/+᭺/+᭺/−᭺−/᭺+᭺/+++/᭺
Costfork=0.2W/mK
achievement
+++−᭺−−᭺−−−−−−
(+):Good;(᭺):average;(−):poor;EPS:expandedpolystyrene;XPS:extrudedpolystyrene;PU:polyurethane.
be to improve a material’s specific feature, while the other
features remain constant or get improved. For example,
if someone achieves to reduce the λ factor of a material,
while the fire-resistance is getting worse or the cost in-
creases dramatically, then such an evolution would not be
characterized as innovative. The possibilities for the im-
provement of the various features of the currently used
materials, in reasonably equivalent forms, are presented in
Table 8.
Keeping in mind the comparative presentation of data in
the previous Tables 7 and 8, as well as the evolution of the
insulating properties of the ‘traditional’ materials, limited
progress can be expected in the field of their conductivity
values. A reduction of the λ-value by up to 10%, whilst
improving the other properties would in that sense be a major
progress. The following points should be of interest for the
future research of the other properties:
• For inorganic fibrous materials, further emphasis has to
be given to the limitation of emissions of dust and fibres
and also to the use of binders. Furthermore, there is a po-
tential for reducing energy consumption in the production
process of the materials, which will in that way reduce
the embodied energy.
• For the organic foamy materials, and particularly for ex-
truded polystyrene, emphasis has to be given to the pro-
pellants used, in order to abolish CFCs and HCFCs, which
are still used by many producers, and to reduce the use
of CO2 as a substitute of the CFCs and HCFCs. A possi-
ble cost reduction would be a major point in making this
material more competitive.
• A further point of research, both for expanded and ex-
truded polystyrene, is the improvement of reaction to fire,
which is possible by using certain additives. Still, these
tend to lead to an increase of the materials’ λ-value. In the
group or foamy materials, particular attention has to be
paid to polyurethane and to the reduction of the toxicity
of gases produced in case of fire.
• In order to accelerate the improvement of the energy be-
haviour of existing buildings, more flexible and versatile
ready to use composite materials will be needed. This will
set increased demands on the mechanical properties of
insulation materials, as they will have to co-operate with
various plasters, foils, particle and chip boards, aluminum
plates, etc. In that sense, the most important aspects of
innovation might be in the development of integrated in-
sulation products. This step is also of significance for the
feasibility of such interventions, which remains always a
delicate matter, depending on current energy retail prices
[22].
• A final point to be thought of is the advance in the har-
monisation of methodologies and criteria used to evaluate
the environmental impact of all the materials all over Eu-
rope. The adoption of a single methodology and the pa-
rameterisation of primary energy consumption during the
production process, remains an open issue for insulation

9. A.M. Papadopoulos / Energy and Buildings 37 (2005) 77–86 85
Table8
Insulationmaterial’sattributesrelatedwithhealthandtheenvironment—basedonthepropertiesofaverage,commerciallyavailablematerials
HealthandenvironmentalimpactInorganicfibrousOrganicfoamyOrganicfibrousInorganicfoamyOther
Glass
wool
Stone
wool
EPSXPSPUSheep
wool
Cotton
wool
CelluloseCoconut
fibres
PerliteFoam
glass
Gypsum
foam
Experimental
cork
Wood
wool
Maximalexposurerates
duringproduction,handling
andconstruction
᭺᭺++++++᭺+++++
Biopersistenceoffibres᭺᭺NANANA++++NANANANANA
UseofCFCs,HCFCs,CO2NANA−/᭺−/᭺−/᭺NANANANA᭺/++++NA
ToxicityincaseoffireNANA᭺᭺−+++++++O/+NA
Embodiedenergy++᭺᭺᭺᭺/+᭺/+᭺/+᭺/+᭺᭺/+O/+O/+᭺
Useofrawresources++−−−+++++++᭺/+᭺/+
Wastedisposal++᭺᭺−+++++++++
Re-useandrecycle᭺᭺++−᭺᭺᭺
(+):Good;(᭺):average;(−):poor;EPS:expandedpolystyrene;XPS:extrudedpolystyrene;PU:polyurethane;NA:notapplicable.
materials, as for many other branches, when coming to
apply a Life Cycle Analysis.
6. Concluding remarks
Enhanced thermal protection is and will remain the most
cost-effective way to construct or rehabilitate buildings with
a reasonable energy consumption, satisfactory thermal com-
fort conditions and low operational costs. This conclusion
has been incorporated in the new European energy regula-
tion, which considers a high standard of thermal protection
as granted, in order to advance to more sophisticated en-
ergy saving measures and to more strict energy performance
limits. Advanced insulation materials are a prerequisite to
achieve them.
Increased awareness towards the environment and public
health is leading to an integrated evaluation of insulation
materials and whilst no one questions their positive energy
balance, there is still significant potential for improving their
overall performance, in terms of environmental impact from
cradle to grave.
Finally, the building construction market may be the most
important single economic branch in Europe, but is a na-
tionally and regionally fragmented market, with a frequently
conservative attitude prevailing. Furthermore, it is a highly
competitive market. Insulation materials have to improve
their performance, but they also have to be adaptive, friendly
to the construction site personnel and, last but not least, cost
effective. The challenges set for the coming years are cer-
tainly interesting and they are calling for a more efficient
co-operation of the research community, the industry and
the legislative authorities.
References
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