Insulation and Industrial Energy

AuthorNigel Keenlyside
Publication Date01 May 1982
Insulation and
Industrial Energy
Nigel Keenlyside
Impelled by the urgency of the energy crisis, one of
business management's newest disciplines is spreading into
most industrial and governmental organisations. Energy
management, in common with its more established
counterparts, is rapidly developing its own litany and iden-
tity. It is estimated that there are now approximately 7,000
energy managers in the UK. They have their own publica-
seminars and exhibitions; they are supported by a
welter of government sponsored advisory services and they
are courted by an ever increasing number of consultants
and experts.
Mineral Insulating Fibre
The member companies of Eurisol-UK (The Association of
British Manufacturers of Mineral Insulating Fibres) con-
vert indigenous raw material into glass and rock fibres and
this is processed into insulation products. The material is
melted and converted into fibre by extrusion or spinning,
and finally a resin bonding agent is applied which is then
cured by passing through ovens. The final products act as
insulators because their structure contains pockets of still
air. Man made mineral fibres are ideal for this because
they are inert, inorganic, non-combustible,
odourless, non-hydroscopic, do not sustain vermin and are
not subject to insidious smouldering.
How the Effectiveness of Insulation is Measured
When it comes to buying insulation there can be some con-
fusion over the different types of material available, their
thicknesses and the claims made as to their respective ther-
Some people regard insulation as being steeped
in jargon. That is not actually so, but such expressions as
"k" and "R" values are not fully appreciated, even
by some professionals. Yet they exist to simplify the pro-
blems of establishing the rate of heat loss.
There are now about 7,000 energy
managers in the UK. They have
their own publications and exhibitions
The "U" value (Thermal transmittance coefficient)
quantifies the ability of a structure to transmit heat. It
stands for units (or Watts) per square metre per Kelvin
(Kelvin being a temperature difference of one degree
Celcius). So a "U" value measurement is the amount of
heat transmitted through one square metre of composite
structure (such as a brick wall) when there is 1°
temperature difference between the air on one side and the
air on the other. It means that in calculating a "U" value
you are calculating the resistance of each component part.
All surfaces (exterior and interior) have their thermal
resistance, as do airspaces or cavities within the structure.
A "k" value (always lower case k) is the amount of heat
passing through one square metre of insulating material
one metre thick, again when there is a temperature
ference ofC on each surface. So U represents the heat
transference through a construction, k through unit
thickness of an insulating material. The lower the "k"
value and the "U" value, the less heat is escaping through
the structure and the better the material is as an insulator.
Man made mineral fibres are
inert, non-combustible, rot-proof,
odourless and do not sustain vermin
The problem is that one is largely dealing with identical
thicknesses. Therefore a convenient formula has been
devised known as the thermal resistance. The "R" value is
a measure of the resistance to heat flow of a material of
any specific thickness. It represents the thickness of the in-
sulation in metres divided by the thermal conductivity
measured in watts per metre per Kelvin.
Here are some typical "R" values of structural com-
ponents of typical thickness:
102mm of brick
16mm of paster (dense)
9.5mm plywood
25mm softwood timber
100mm concrete
150mm concrete
Now compare the "R" value of mineral fibre material:
Mineral fibre building roll 60 mm
Mineral fibre building roll 100mm
Mineral fibre building roll 160mm
Mineral fibre roof board 25m
Mineral fibre roof board 50mm
Mineral fibre roof board 100mm
In other words, four inches of mineral fibre insulation has
the same thermal resistance as seven feet of solid
MAY/JUNE 1982 23

To continue reading

Request your trial