STARTLINK COMPOSITE HOUSING
J. A. Hutchinson1, M. J. Singleton2
1
Palace of Westminster
Startlink Systems Ltd
2
Abstract: Startlink is a modular construction system based on 10 Pultruded profiles that link together
using bolts and snap-fit connection to build houses rapidly. The material is almost unknown in the
industry yet has remarkable properties well suited to house building: lower thermal transmission and
expansion than steel, concrete or brickwork, stronger than steel but ¼ of the weight with good fire
resistance and sound attenuation. It is also stable, inert and impervious to moisture, requiring only the
addition of insulation to build houses. With appropriate insulation, a Startlink house has lower embodied
energy than a timber frame building, avoids site waste (20-25% of all UK waste) and reduces shipping
and assembly costs because of the light weight. Lightweight houses are easier to build and heat but lack
thermal mass to even out summertime temperatures. The Startlink solution is to use a “green” roof which
retains water for evaporative cooling and the thermal mass of the ground below. The low-maintenance
system is easy to alter and reuse and offers the possibility of extremely energy efficient housing. By
avoiding steel and concrete, Startlink houses are quick to build, environmentally friendly and up to 25%
cheaper than traditional building.
Keywords: Cost, Speed, Energy, Waste, Environment
1 Pultrusion
Mild Steel
430
430
205
7850
Concrete
35
9
20
2400
39 *
1920
Pultruded GRP
580 *
700 *
Density kg/m3
Architect, hutchinsonj@parliament.uk
Inventor, mark@startlink.co.uk
Young’s Modulus
(GPa)
2
Tensile Strength
(MPa)
1
Table 1: Material properties [1]
Material
Compressive Strength
(MPa)
Although composites have been used in building
construction for over forty years, little is known within
the industry about the superior properties and structural
performance of pultruded glass reinforced composite
profiles. Pultrusion is a mechanical process that draws
continuous fibres impregnated with a thermosetting
resin through a heated die that polymerises the resin and
forms the shape of the pultruded profile in a continuous
process. Electrical grade E glass fibres are commonly
used to reinforce a polyester resin matrix although
phenolic resin may be used to offer superior fire
resistance.
Pultrusion optimises the fibre-matrix ratio, which
has the effect of stiffening the composite. With the right
matrix, the value for Young's Modulus can be as high as
44GPa along the linear axis when high performance Sglass reinforcement is used. The accepted minimum
value for profiles less than 5mm thick is 17GPa and
thicker structural profiles is 23GPa. The comparable
figure for conventional GRP is between 7 and 10GPa.
Softwood suitable for structural applications in
buildings has a figure of between 7 and 11GPa.
Pultruded profiles have up to four times the strength-toweight ratio of mild steel but lack its rigidity. To
achieve equivalent strength and stiffness, pultruded
profiles are still half the weight of mild steel. It is
possible to achieve more than five times the strength-toweight ratio of reinforced concrete. The values for
tensile and compressive strength are impressive, as can
be inferred from the table below, because the composite
starts to exhibit the mechanical properties of E glass
fibres, which have a tensile strength of up to 2,500MPa.
(S-glass fibres used in high performance applications
have a higher tensile strength).
* The quoted figures only apply along the axis of the
reinforcing glass filaments.
The pultrusion process has the lowest labour
content of any composite manufacturing system and
produces the highest mechanical performance along the
lineal axis. Recent developments in the US and Canada
have enabled much thinner, more complicated profiles
to be produced to make frames for window
manufacturers.
Thinner profiles allow increased
pultrusion speed which brings down cost. Thicknesses
below 2mm impart slight flexibility to sections which
open the possibility of developing snap-fit assembly. In
Holland, lightweight core materials that can be
pultruded have been developed. With thicknesses from
2mm to 6mm, they replace glassfibres in the middle of
thicker sections with a honeycomb of micro spheres.
The effect is to further reduce weight and cost with
minimal mechanical loss. By taking advantage of such
techniques, pultruded composites offer a cost-effective
alternative to more familiar building materials.
The preponderance of glass in the composite
achieved by pultrusion improves the performance in
relation to thermally induced movement, so that it
behaves more like glass and less like the matrix
polymer. An American manual quotes a linear
coefficient of thermal expansion of only 5.2x10-6/unit
length/degree Celsius, which is less than half that of
reinforced concrete or mild steel. The Technical
Manual of a leading UK pultruder, Fibreforce Ltd,
quotes a figure of 10 x 10-6/unit length/degree Celsius.
For UK applications, the Fibreforce Ltd figure is the
more reliable.
Pultruded composite profiles are electrically
insulating; they are intrinsically resistant to the passage
of heat; they are acoustically absorbent and attenuate the
passage of structure-borne sound; they are mostly
impermeable both to liquid water and to vapour
(although there is some absorption by any polymer
matrix); they are resistant to 'freeze thaw'; they are acid
resistant and alkali resistant provided that full
consideration has been given to the selection of a
suitable resin matrix and the right reinforcement; they
are, for the most part, chemically inert, so that there is
minimal risk of release of Volatile Organic Compounds
while they are present in a building and finally, they can
be made to have better performance in a fire than
unprotected mild steel, because the surface of the
composite tends to 'char’, which protects the core of the
structural section against further burning. Phenolic
resin filled with POSS Nanoparticles has demonstrated
no loss of performance at up to 400°C. Provided that
the correct production techniques are adopted, pultruded
profiles can be made to be entirely resistant to the
destructive effects of the UV components in sunlight.
It can be confidently asserted that pultruded glass
reinforced
composite
profiles
are
highly
competent engineering components which would be
eminently suited to a large number of building
construction applications, not least components for
house building.
2 Startlink System
Startlink is a modular building system that uses ten new
pultruded profiles in combination with a few standard
profiles to construct a house without using concrete or
structural steel. The main elements are a floor panel,
flat panel and perimeter profile 6mm thick with
lightweight cores. Other profiles, apart from the 5mm
Beam, are 3mm thick or less. Flat panels have short
return legs each side that hold 6mm round extruded
gaskets. Pairs of gasketed legs slot into a single strut
and either side of deeper box struts to make waterproof
seals in walls 240mm, 120mm thick and the roof. A
snap-fit 50x25mm channel locks them in place and links
floor panels together. The Beam profile has two
purposes: to stiffen the floor panel and when cut in two,
to form the upper and lower chords of a roof truss.
Bonded to floor panels at 600mm centres, it allows a
span of 5M at 1.5kN/M2 loading and deflection limited
to L/360. Such a panel is light enough to be carried by
two people and the lower part of the beam
Figure 1, Startlink components
accommodates Flat panels to make a ceiling. The
overall depth of floor to ceiling is 240mm and has
ample space between for insulation or sound proofing.
Exterior walls 240mm thick have room for 225mm of
insulation with thicker insulation in the roof to make an
extremely well insulated building. The sealing gaskets
will offer a very high resistance to unwanted moisture
and air permeability. Two remaining small profiles
connect walls at 90° and varied angles. Walls and
floors have integral modular ducts behind snap-fit
channels to allow easy installation of click-fix modular
plumbing and wiring systems. The same ducts enable
blind fixing by inserting Unistrut nuts which lock into
channels in struts and floor panel.
factory. All cutting and drilling operations can be
carried out on the pultrusion line using Computer
Numerically Controlled machinery. This means that
finished components can be delivered to site from the
factory with the minimum labour content and transport
requirement. CNC machining could even be linked
directly to architects Computer Aided Design drawings,
short circuiting the usual time consuming processes. An
assembly team on site would simply bolt and snap
together the architect’s design in a very short time.
Using pile foundations instead of mass concrete, no wet
trades or skilled labour would be needed. Startlink is a
modular, lightweight, energy saving building system
that also saves time and produces no site waste.
3 Waste Saving
4 Building Advantage
Building construction is a complicated but often
wasteful process. Waste and off-cuts from materials
used on site are seldom recycled. On-site construction
tends to be chaotic unless the standard of site
management and supervision is of the highest order,
which is the exception rather than the rule in jobbing
building work. Site confusion and disorderliness gives
rise to wasteful practice. An estimated 72.5 million
tonnes of construction and demolition waste are
produced in the UK annually. This is around 17.5 % of
the total waste produced in the U.K. Furthermore, 13
million tonnes of construction materials are delivered to
site and thrown away unused every year [2]. If building
processes were to be moved away from site to the more
controlled conditions of a factory, the standards of
supervision and quality control would automatically
improve immeasurably, which would have the effect of
greatly reducing waste.
Another means of reducing waste is to construct
modular buildings in which all the parts are predesigned and fabricated to fit neatly together without
cutting. Modular construction is far more suited to
factory production, because the standard, modular kit of
parts can be mass-produced, thus saving time, materials
and a great deal of money.
Off-site production that is modular tends to be
modular on a large scale. It is only limited by the size
of prefabricated components that can be delivered by
road. Large prefabricated boxes that arrive on site fully
finished are more expensive than traditional building
methods. Panellised construction is popular in the US
where it builds 45% of the shells of single and two
storey houses. Composite Building Structures of Florida
is constructing panels using pultruded composite frames
to resist hurricanes [4]. The process is less suited to the
more compact European environment. Structurally
Insulated Panel systems offer a halfway house but lack
the flexibility of traditional methods. Each system
depends on concrete for floors and foundations. Every
tonne of Portland cement manufactured releases a tonne
of CO2 into the atmosphere.
Pultrusion is carried out off-site and can produce a
modular set of finished building components at the
Pultruded composite buildings can be made to be
air tight and highly vapour-resistant without the need to
install vapour control layers, air sealing mastics in
joints or 'breather' membranes behind rain-screen
elements. There is no need for rain-screening, because
this material is, in most aspects, resistant to the passage
of water (although, any polymer matrix will absorb
some moisture). There is likely to be a reduced need for
additional fire protection layers owing to the better fire
performance of pultruded profiles compared with that of
mild steel. This performance could be improved even
more, should the need arise, by switching to a phenolic
matrix.
Provided that requirements for fire resistance do not
give rise to the need for the installation of additional fire
lining, entire buildings can be made from pultruded
composite profiles with no need for the addition of other
membranes,
mastic
sealants,
coatings
or
cladding/siding. The only extra item required would be
a layer of insulation to be installed between the two
construction leaves, which is a necessity for any well
insulated, energy saving building, whatever it is made
of. The resulting simplicity of the building envelope
saves time in the construction process. It allows a
higher degree of insulation, space for space than other
construction systems. It also saves energy, because all
of the additional layers needed in other forms of
construction consume energy in their manufacture and
transportation.
The dimensional stability of pultruded composite
components has the effect of eliminating the possibility
of ambient air infiltration at the joints between panels
and window/door frames. Differential movement
induced in commonplace building materials either
thermally or by changes in humidity would impose
stress on these joints with an attendant risk of rupture or
fatigue failure of sealing tapes or mastic sealants, which
would result in copious infiltration. For the best possible
results, it would be sensible to specify pultruded profile
window and door frames, thus ensuring materials
compatibility between the panels and the frames.
Pultruded composites are low maintenance
materials, unaffected by termites, rust or rot. They can
be clad with other materials but also offer an unusual
choice of low-cost surface finishes as a consequence of
the pultrusion process. In the US, co-extrusion has been
developed to provide a very thin Acrylic thermoplastic
coating in a range of colours. It offers a durable, high
quality finish. Alternatively, pigments or decorative
materials can be added to the matrix resin to impart a
range of different appearances. The surfacing veil will
also accept printing and when encapsulated in the
pultrusion, offers a variety of patterns and colours as
wide as wallpaper. This extensive range of options
offers architects considerable choice when it comes to
specifying a Startlink building’s appearance.
5 Energy Saving
The greatest potential for energy saving is below
ground. Because pultruded profiles are so light, mass
concrete foundations would not be needed. Instead, a
Startlink building would be best supported on pultruded
piles driven or, if threaded during pultrusion, screwed
into the ground beneath the building to a depth
determined by its bearing capability. A Startlink
dwelling accommodating five people could be
adequately supported on as few as four piles. The
quantities of raw materials and energy required to
construct the foundation of a Startlink building would
be a tiny fraction of those required in a conventional
building.
The embodied energy in pultruded glass reinforced
composite profiles is similar to or slightly higher than
that of mild steel and above that of reinforced concrete
when measured by weight. The figures for mild steel lie
between 35 and 59 megajoules per kilogram. For
reinforced concrete it could be as high as 28MJ/kg, (the
exact figure would depend on the amount of steel
reinforcement). Pultruded profiles reinforced with Eglass have around 50-54MJ/kg [3]. However, the fact
that they are so much lighter and less dense than either
of the two conventional structural materials has the
effect of greatly reducing the embodied energy in any
structure made from them.
Lightness in pultruded composite structures
automatically reduces their dead-load which, in turn,
reduces the quantity of material needed to make the
building, for the simple reason that less structure is
needed in its lower parts to support the dead-loads
imposed by the upper parts. Lightweight buildings
consume far less of the earth's resources and nonrenewable hydrocarbon fossil fuels than heavy ones.
If an entire building can be made as a kit of parts to
fit on to one truck, there need only be one delivery to
site by means of a large vehicle consuming hydrocarbon
fossil
fuel.
Normally,
conventional
building
construction necessitates many vehicle movements to
and from site, not only by delivery trucks, but also by
the cars and other vehicles carrying the tradesmen to
work and home again. If site time were greatly reduced
as a result of the recourse to modular, prefabricated
building techniques, there would be far fewer journeys
made to site by building workmen.
If the materials used for the fabrication of the kit of
parts were, in themselves, extremely light in weight and
easy to handle, there would be a considerable saving in
fuel consumed, both in transportation and by the
reduction in the need for motorised cranes and platform
lift vehicles.
Lightweight buildings are much easier and less
energy demanding to heat in winter. The heating plant
can be used to heat the occupants. No energy is wasted
in heating massive structure.
Similarly, there is no heavy structure to become
heated as a result of summertime solar gain. No
mechanical cooling would be required to remove heat
from massive building elements. The summertime
performance of pultruded glass reinforced composite
buildings can be greatly improved by application of
reflective materials to the external surfaces, which could
easily be incorporated in the pultrusion process.
Lightweight buildings are bound to have low
thermal mass. The interior of a highly insulated but
light building could become overheated in summer. To
overcome this potential problem, Startlink buildings
would be configured so that internal convection would
draw in cool air from below ground level, where the
temperature is constant at 10-11º Celsius. This principle
is by no means new. The Empire Hall in Harrogate,
built in 1901, is cooled in this way. Another way of
keeping a lightweight building reasonably cool in the
heat of summer is to specify a “green” roof. This would
add thermal mass and retain water. Evaporating water
will take some of the latent heat from the building’s
interior.
The Startlink system is modular and factory based
with the minimum need for any site presence. It uses the
lightest low cost engineering components currently
available, which are pultruded glass reinforced
composite profiles. All of the fuel saving features
described above are evident to the maximum possible
degree in the Startlink system.
6 Environmental Benefits
Modular buildings are the easiest to recycle. The
reason is that the component parts can be dismantled at
the end of a building's life and taken away for re-use in
another modular building. The long life-expectancy of
pultruded glass reinforced profiles would enable
Startlink components to be re-used in other buildings
after a first building performance life of forty or even
fifty years. The Startlink system uses snap-fit assembly
which obviates the need for nails, screws and adhesives.
This makes it easy to alter, extend or dismantle Startlink
buildings. By unsnapping the channels and unbolting
the connections hidden behind, pultruded components
can be removed, free from other embedded materials.
Disassembly from outside can be prevented by inserting
wedges during assembly to prevent unauthorised
unsnapping. The modest number of pultruded parts in a
Startlink building combines with modular plumbing,
wiring and insulation to add a new simplicity to house
building that accelerates the building process and even
opens the door to DIY.
At present, the resin matrix in composite profiles is
made from the refined products of crude oil. However,
pultrusion improves the composite so that its
preponderant constituent is glass which is made from
silica - one of the most abundant minerals on the
planet's surface. There are realistic prospects of some
matrix resins being made from plant-derived
substances in the very near future. Phenolic resins
could, in the future, be made from organic sources.
Pultrusion can be done with polyurethane. The polyol
component of PU can be made from organic material
although, at the present time, it is not yet possible to
make the diisocyanate cost effectively from anything
other than petro-chemical feedstock.
The thermo-setting plastic matrix cannot be
recycled as would be the case for thermoplastics such as
polythene
or
polypropylene.
When
Startlink
components have finally reached the ends of their useful
lives, there are several available options. The
components can be ground to make a filler for other
materials. They can also be reduced to their original
constituents by Pyrolysis, Supercritical Water
processing or Fluidised-bed processing [5].
Pyrolysis is the heating of waste in the absence of
air (oxygen) and is used to separate composite material
into its original constituents. The process breaks
composites down into gas, oil, fibre and a small amount
of carbon. The oil and fibre obtained can both be
reprocessed into composites. Supercritical water
processing can hydrolyse and decompose composites
effectively and cleanly without charring. The process
involves heating waste composite in steam at 300 to
500°C resulting in the material being decomposed and
partially hydrolysed to phthalic acid, styrene, glass fibre
and oil. A fluidised bed is a chamber containing sand
which acts like a fluid when suspended in an airstream.
The chamber is heated to between 450 and 500 °C, too
low and the fibres will not be fully cleaned, any higher
and the fibres suffer a reduction in strength. Choppedup composite material is placed in the bed. The resin is
evaporated and the fibre is blown by the airstream to a
collection point for recovery. Gas enters a secondary
combustion chamber for heat recovery leading to clean
flue gas and recovered energy.
In Japan, a supercritical water processing system
has been developed with a generating unit fuelled by
mixed waste plastics which are thermally decomposed
to generate gas which is in turn used as a fuel to produce
supercritical water and electricity. Using this system, it
is feasible to recycle both composite waste and general
plastics waste without any pre-treatment such as
washing and sorting. It is thought that such a process
can be economically viable as the system generates
electricity which can be sold, creating considerable
income, and also handling fees can be charged for the
acceptance of waste plastics for thermal treatment. Little
residue is produced by the system meaning only a small
amount needs to be landfilled.
Composite waste can be incinerated at a
temperature in excess of 1200 degrees Celsius to effect
the complete destruction of the time-expired composite.
In order to maintain the combustion temperature once it
had been reached, extraneous energy would be needed
such as waste plastic from time-expired poly-tunnels
provided that no chlorine was present. The residue
arising from burning would be a highly alkaline
siliceous clinker. The Japanese use this as an inclusion
for cement manufacture. The alkaline and cementitious
residue could, alternatively, be diverted for separate and
specialised applications, such as the manufacture of
reconstructed stone as building ornament or cladding.
7 Cost Effectiveness
The Office of the Deputy Prime Minister set a
competition to reduce housing costs to £60k and
ministers have recently said that greenness will replace
cheapness in the second phase of the competition, which
will take the form of ‘small scale eco-community
developments’ rather than house types [7].
Analysis of the Startlink pultruded profiles required
to build a 75m2, 2 storey house based on profile costing
two years ago, suggested a total pultrusion cost of c.
£25k. A recent re-costing of slightly refined profiles
shows no overall price increase. In the same period,
steel has doubled in price and energy costs have
increased markedly. Pultrusion costs are governed by
raw material costs, set-up time and machine speed.
Thinner or core-filled profiles reduce expensive material
use, increase machine speed and long production runs
all drive down pultrusion costs. Startlink uses thin and
core-filled profiles and can expect extremely long
production runs to build houses. This offers the prospect
of greenness becoming available with cheapness.
More than two thirds of new housing development
is now on ‘brownfield’ as opposed to ’greenfield’ sites.
The former tend to pose problems for developers
because site boundaries are often awkward, meandering
and/or severely confined. They may also present
difficult ground conditions with old footings, slabs and
remnants of former buildings still present and
sometimes, toxic contamination below ground. Sites
which once contained earlier buildings or structures are
often beset by problems of being overlooked from the
windows of buildings on adjacent sites. These inherent
site constraints almost always give rise to increased cost
for the developer.
Modular building systems are usually only cost
effective when there is a great deal of repetition in the
site being developed. This is restrictive, because it
places necessary limits on the number of dwelling types,
the plan ‘footprint’ of the dwellings and the external
building envelope of a dwelling or block of dwellings.
Ordinarily these have to be as simple, regular and
rectilinear as possible. Any ‘bespoke’ building items or
one-off special construction forms would greatly
increase the cost of a modular housing development.
Particularly severe design constraints are imposed by
large panel building systems. All the currently available
SIP systems consist of large panels which, by their
nature, lack the necessary versatility to be
accommodated readily within sites with complicated or
confined boundaries. What is more, once constructed,
large panel system buildings are almost impossible to
extend or re-plan without incurring daunting expense as
a result of changing the configuration of the large
modular panels.
Despite consisting of only ten pultrusion profiles,
Startlink is extremely versatile. This is a great
advantage in contemporary housing applications.
Startlink dwelling plans and elevations could easily be
altered, adapted or re-configured to fit both difficult site
conditions and future changes of need, where the
proposed changes would affect overall size or shape of
floor plan. Because the Startlink panels can be easily
and accurately cut to fit ‘one-off’ conditions without
any adverse effect on the structural integrity of the
building as a whole, the designer always has the
opportunity to change the position of window or door
openings to overcome constraints imposed by site
geometry or other factors, such as overlooking from
neighbouring buildings. The modular grid determining
the size increments of Startlink components can be
stretched or contracted without undue difficulty to fit
non-standard site dimensions, not only because the
panels can easily be cut to non-standard sizes, but also
because the pultruded beams and columns are
sufficiently resistant to bending and shear to enable the
designer to incorporate non-standard and larger spans
and non-rectangular column grids, should the need
arise.
The good engineering properties of pultruded GRP
offer other intrinsic benefits to designers, who would
have far greater opportunities to model elevations by
resort to cantilevering or recessing upper storeys or
parts of storeys. The Startlink profiles are well able to
accommodate and resist the additional shear and
bending stresses that occur in jettied or cantilevered
floor and wall panels on main elevations. Too many
modular building systems used for housing or other
buildings generate monotony and blandness in their
external form. Startlink does not carry this innate
disadvantage. On the contrary, the designer has greater
opportunity for freedom of aesthetic expression owing
to the fact that Startlink enables him or her to be
structurally adventurous. Such opportunities are not
provided by large panel systems. Exciting design
expressions are theoretically possible with steel or
timber framed systems, but in reality, the cost of
departing from standard plan and elevation
arrangements is so great as to deter the developer and
building designer from even momentarily considering
such options. Startlink would be the only modular
system on the market capable of offering developers’
architects the opportunity to be genuinely expressive
and innovative in their designs.
The majority of ‘brownfield’ sites are in urban
areas. It follows, therefore, that Startlink is particularly
suitable for urban housing on both infill sites and on
derelict or abandoned urban land formerly occupied by
heavy industry. In the event of a potential development
site being contaminated by toxic residues as a result of
earlier industrial processes, it would be necessary to
form robust barriers resistant to Volatile Organic
Compounds and Polycyclic Aromatic Hydrocarbons. It
is far easier and cheaper to do this beneath Startlink
dwellings, which do not require ground slabs and which
can be securely supported on as few as four mini-piles,
than would be the case with any other building type,
whether traditionally built in-situ or pre-fabricated and
modular. The joints of Startlink floor panels can also be
assembled with effective and permanent sealing which
would resist the passage of gas or vapour, including
radon gas emanating from granite strata below ground
and PAH emissions from former gas works sites. The
suitability of Startlink as a building system for heavily
contaminated urban ‘brownfield’ sites is unrivalled. No
other building method would offer such cost-effective
and easily executed construction to any potential
developer.
Figure 2, Startlink Floor components
Figure 3, Startlink Floor assembly
The Affordable Rural Housing Commission has
reported on rural housing shortages and recommends
the building of a minimum of 11,000 affordable houses
a year in rural areas [5]. The great benefit offered by
Startlink in rural areas, aside from its low cost and ease
of construction, would be that a dwelling could be
constructed within an existing agricultural building that
had become derelict or otherwise redundant.
Alternatively, the building could be concealed behind an
existing farmyard wall, provided that it was restricted to
one storey in height. All the components are light
enough to be carried and assembled by two workmen.
With Startlink, there would be a change of use and an
upgrading of an existing rural building without any
change being apparent externally, other than minor
repair of decayed brickwork, rubble walling or other
existing external fabric. Pultruded glass reinforced
polyester will not rot or decay in situ. Startlink
components, therefore, can be made into a serviceable
and watertight building to sit inside a leaking or slightly
dilapidated existing one. Because of its lightness, the
new internal building could rest on its own foundations,
which would take the form of four or, possibly, six
mini-piles driven or screwed through the floor of the
existing building.
Figure 4, Startlink Exterior Wall components
Figure 5, Startlink Exterior Wall assembly
If a Startlink building were to be erected in a rural
setting either as a building on its own or in the context
of existing traditional or historically important ones, the
external treatment would depend entirely on the wishes
of planning officers and the client or client body, which
could be a rural housing association. The external
facades can be either traditional or modern, whichever
approach is thought to be more appropriate. Cladding
with brickwork, rubble stone or even dressed masonry
would increase the cost, but the homes would still be
much cheaper to build than conventional alternatives. It
is strongly recommended that 'green' or 'brown' roofs be
specified in all cases where the Startlink building was
not constructed within an existing building envelope. As
well as settling inconspicuously into a rural landscape,
these roofs would contain both thermal mass and liquid
water, thus helping to maintain cool internal
temperatures in summer. Another source of essential
thermal mass would be the ground on which the
dwellings were constructed. The temperature at one
metre below ground level and lower is constant at 10°11°C. A suitable insulant would be Rockwool at
150mm thickness in floors, 200mm in walls and 300mm
in roofs. This basalt-derived insulating material is
ultimately either bio-degradable or recyclable. It does
not offer refuge to insects or rodents. It is sound
attenuating and fire-proof. It has the lowest embodied
energy of any inorganic insulation at 17MJ/kg [8].
Because the cavity in a Startlink home will always be
dry, Rockwool would never be moistened and thus
would not ‘slump’ within the void. Finally, Rockwool
does not contain ozone depleting or ‘greenhouse’ gases
such as HFC (up to 20,000 times the ‘greenhouse’
potential of CO2 [9]) or pentane (the latter saturated
hydro-carbon converts into two greenhouse gases as it
degrades on release into the atmosphere, which are
methane and carbon dioxide).
Pile foundations would be made of pultruded GRP
or GRP waste/durable timber composite piles as
developed by Tim Reynolds of the BRE for use in
low/medium rise building construction. The latter
method would offer the advantage of sequestering
carbon below ground. Absence of mass concrete from
the foundations would simplify the installation of
services. It would also greatly reduce total CO2
emissions arising from the construction (the
manufacture of one tonne of Portland cement results in
the release of an additional one tonne of carbon dioxide
into the atmosphere). The inclusion of micro-generating
devices on every dwelling is also recommended, subject
to agreement with planning officers. This would
provide some of the electrical power needed to drive
water and space heating systems. Alternatively, the
micro-generating devices, either wind driven or photovoltaic, could supply power to ground sourced heat
pumps. In rural areas, there would be no gas supply.
Apart from supply problems in isolated parts of the UK,
the sources for extraction of this hydro-carbon fossil
fuel are in rapid depletion. In fifteen years time, it is
entirely possible that gas will be both scarce and
expensive relative to other fuels. Startlink would be
designed in detail to accommodate the principle of
micro-generation of electrical power from the outset.
Figure 8, Startlink Roof assembly
8 Global Solutions
Figure 6, Startlink Interior Wall
Figure 7, Startlink Roof components
Because of global warming, changes in weather
patterns give rise to sudden localized downpours and
flooding. The effect on traditional buildings is dramatic
and costly to repair. Pultruded buildings are unaffected
by water and could survive flooding without
consequence if designed to resist the pressure of
floodwater. They are also light enough to be constructed
on floating platforms in areas affected by rising sea
levels. Earthquakes in inhabited areas can cause
catastrophic damage to massive buildings with load
bearing walls. Falling masonry crushes inhabitants or
traps them in rubble. In contrast, pultrusions, which
obey Hooke’s law, continue to deflect under increasing
loads. The fixings are likely to fail before rupture
occurs in pultrusions. Even when ruptured and broken
open, the lightweight panels, columns and beams would
be far less likely to inflict serious injury on the
building’s occupants when compared to the
consequence of the collapse of a massive building.
Lightweight flat-pack houses also have a role in disaster
relief. Easy to ship and simple to construct, they offer
fast solutions to unexpected disasters.
The Barker report on housing [10] proposes an
annual increase in UK house building of 120,000 houses
above the current level of 160,000 to even out house
price increases to the EU average. To supply 1% of the
existing UK house building market would require an
additional 8000tonnes of glass fibre production. To
supply this amount of glass fibre, Saint-Gobain would
need to double its glass furnace capacity in Europe and
the quantity of pultrusion machines would need to
multiply extensively. To benefit from the many
advantages offered by pultrusion in the construction
market, major investment will be required in material
and production facilities.
Pultruded glass reinforced composite profiles are
currently the most energy efficient, structurally
competent components available for construction use.
Startlink is a patented modular building system of great
elegance and simplicity. The combination of these two
elements offers the possibility of constructing extremely
energy efficient, low/medium rise buildings quickly and
cost effectively. The Startlink system is particularly
suited to the construction of energy efficient, affordable
housing.
The demand for affordable housing is worldwide
and around 50% of all global resources go into the
construction industry. 45% of energy generated is used
to power and maintain buildings and 5% to construct
them. The heating, lighting and cooling of buildings
directly through the burning of fossil fuels (gas, coal,
oil) and indirectly through the use of electricity is the
primary source of CO2 emissions and accounts for half
of all global warming gas emissions [2]. Global
warming calls for drastic measures to reduce energy
consumption and carbon emissions. Composites can
provide the solution.
References
[1] Paper from 2004 Annual Conference of the
Network Group for Composites in Construction in
Swansea, South Wales.
[2] The Chartered Institute of Building: Sustainability
and Construction. www.ciob.org.uk
[3] J. E. Gordon. The New Science of Strong Materials
*In the absence of reliable data about the embodied
energy in a pultrusion, the quoted figure has been
calculated by combining the embodied energy in
unsaturated polyester: 90MJ/kg, with the embodied
energy in boro-silicate glass filaments: 26MJ/kg, in
the ratio 1:2 which reflects the matrix:fibre
proportion of a pultrusion. An addition of
5.5MJ/kg has been made to the result of this
calculation to reflect the increased matrix
proportion in the veil coat together with the energy
used to heat the pultrusion die, to draw the
finished pultrusion from the die and to cut and
handle the finished product.
[4] www.cbs-homes.com
[5] Dr Sue Halliwell. End of Life Options for
Composite Waste – Recycle, Re-use or Dispose?
National Composites Network. www.ncn-uk.co.uk
[6] The Affordable Rural Housing Commission. Final
Report. 17 May 2006. www.defra.gov.uk
[7] RIBA Practice Bulletin No 350. 18 May 2006
[8] Rockwool Life Cycle Analysis.
[9] Greenpeace.
[10] Kate Barker ‘Review of Housing Supply: Securing
our Future Housing Needs’ March 2003