| In 1907, Belgian chemist, Dr Leo Hendrik Baekeland | | | | fibreglass for a whole new variety of building |
| first invented plastic materials, with his discovery of | | | | applications - including window frames. |
| the first thermosetting phenolic resin compound. This | | | | Windows: For the past 30 years there has been a |
| was used to manufacture the first plastic products | | | | struggle to establish the optimum window material |
| under the brand name of 'Bakelite'. The best known | | | | between, timber, PVC and aluminium. PVC currently |
| examples of Bakelite, in UK, were the original | | | | dominates the housing market, whilst aluminium |
| telephone handsets and motor car distributor caps - | | | | dominates commercial, 'non-housing' applications. |
| distinctive for being hard, smooth and glossy in the | | | | Timber encroaches onto the housing market, too but |
| only available dark brown colour. | | | | the inevitable regular and costly maintenance makes |
| The history of plastic developments has since been | | | | it impractical for long term, whole life cost sensitive |
| long and multi-facetted, from the manufacture of | | | | applications, despite improvements in preservative |
| cheap children's toys, to the heat resistant nose cone | | | | treatments (which tend to have poor sustainability |
| on the NASA Space Shuttle. In fact, there are now | | | | credentials) and water based finishes. |
| more varieties of the different types of plastic | | | | However, the rapidly increasing awareness of climate |
| materials - than there are species of timber, with | | | | change and sustainability has made specifiers |
| which we are generally more familiar. | | | | re-assess these incumbent materials and have often |
| For example, Timber varieties have their own unique | | | | found them wanting against this new environmental |
| characteristics and benefits, which justify their | | | | analysis. PVC, for example is condemned by |
| individual usefulness. For example, softwoods are | | | | Greenpeace and GHA (The Good Homes Alliance), |
| generally cheaper and more sustainable but do not | | | | for its high levels of human toxicity and CO2 |
| last as long as hardwoods, externally, in our maritime | | | | emissions, released during manufacture, in use and |
| climate but they perform well indoors. Similarly, the | | | | upon disposal; whilst aluminium is criticised for its high |
| Meranti and Luan species of hardwood are far less | | | | embodied energy during manufacture and its very |
| durable than the oily Teaks and resilient Iroko | | | | low thermal insulation. Also, the most commonly used |
| varieties. However, Douglas Fir is a slow grown | | | | Mahogany timbers can only grow in the Tropical |
| softwood with a solid reputation for external | | | | rainforests, which, due to excessive deforestation, is |
| durability, whilst Balsawood is a species of hardwood | | | | reducing the Earth's capability to heal itself from the |
| that would hardly stand the test of time and | | | | effects of rising CO2 levels, since they absorb CO2 |
| strength in any climate! So it is important to | | | | and generate oxygen in return, through |
| understand the differences and to know which | | | | photosynthesis. The Rainforests are not called 'the |
| variety is ideal for any particular application. | | | | Lungs of the World' for nothing! |
| Plastics are similar, requiring a good understanding of | | | | So it is - that at the very time these product |
| their different capabilities in order to select the right | | | | shortcomings have been identified - a solution |
| type for any given application. All plastics share some | | | | appears to have arrived! |
| common features, with the main one being that they | | | | GRP Fibreglass suffers from none of the above |
| are impervious to water. This is a useful start, | | | | limitations which afflict other materials and is, |
| especially for external applications - and establishes | | | | therefore, ideally suitable for window applications, |
| the first and compelling advantage over timber. Two | | | | whether for commercial projects or for housing. The |
| common forms used in the construction industry are | | | | material is made 50% from sand, the most abundant |
| 'thermo-plastics' and 'thermo-sets'. | | | | substance on the planet, which has an inherently low |
| Thermo-plastics, like PVC, are cured by heat, which | | | | thermal conductance and therefore generates lower |
| enables them to be softened and re-formed like | | | | U values than other materials can achieve. Thus U |
| candle wax, by the subsequent re-application of heat, | | | | values of 0.9 W/M2K across the whole window is |
| causing them to melt if sufficient heat is applied. | | | | possible. Furthermore, the extreme strength, |
| They are dimensionally volatile under changing | | | | durability and immunity from the climate provides a |
| temperatures, having a high coefficient of expansion. | | | | maintenance-free life expectancy of 50 - 75 years, |
| Thermosetting resins, however, are chemically cured, | | | | which dwarfs all alternative window materials - and |
| thus their performance characteristics are locked in, | | | | creates a spectacularly good 'best value' comparison |
| or 'set', during manufacture, so no amount of heat | | | | against all-comers, including the cheapest, softwood - |
| can reverse the process, or subsequently mould or | | | | and after only 16 years in that case. |
| melt them. Thus, they provide a far more reliable and | | | | Pultruded GRP is 65% glass, which reduces thermal |
| durable compound for external applications where | | | | conductance and expansion, close to that of glass |
| significant temperature changes are experienced and | | | | itself, thus reducing friction and wear between sealed |
| dimensional stability is required. | | | | units and frames. In addition, up to 33% of the glass |
| As well as different resin systems having their own | | | | comes from a recycled source, scoring additional |
| unique attributes - significant development has been | | | | points on any BREEAM or Code for Sustainable |
| undertaken to develop high performance hybrids by | | | | Homes assessment. The frames can also be recycled |
| adding other components to create new | | | | upon disposal by grinding down for use as filler in |
| 'super-strength' compounds, called plastic 'composites', | | | | concrete to improve the binding agent of the mix. |
| or 'composite materials'. Such composites, take the | | | | It is the sheer strength of pultruded GRP that |
| strong and reliable 'thermosetting' resin system and | | | | astounds most new comers, having twice the |
| add glass or carbon fibres into the mix, to act as a | | | | strength to weight ratio of steel and five times that |
| reinforcing binding agent to spread any stress loading | | | | of reinforced concrete. Fact! Aluminium of course is |
| and give considerable additional strength to the end | | | | much softer than either steel or GRP - and PVC is |
| product. The resultant composites considerably | | | | weaker still, despite its essential internal metal |
| exceed the strength to weight ratio of steel and | | | | reinforcement, which ironically creates a cold bridge |
| aluminium - and still, of course, remain impervious to | | | | to further lower its attainable U values. |
| water. | | | | In practice, GRP scores well over all other window |
| These astonishingly strong and durable composite | | | | materials, too, being the only material which provides |
| materials are called FRPs (Fibre Reinforced Polymers) | | | | zero maintenance and yet which can be either |
| better known as 'GRP', 'Fibreglass', 'carbon-fibre' and | | | | repaired or repainted if damaged, at any stage of its |
| 'graphite' - and are invariably found in the best sports | | | | life, without triggering the need for any future |
| equipment (skis, golf clubs, tennis racquets, fishing | | | | maintenance. By comparison, aluminium and PVC |
| rods, etc). The motor and aeronautical industries have | | | | cannot be repaired or recoated commercially and so |
| also embraced this technology which provides great | | | | their appearance will gradually diminish until it becomes |
| strength with lightness of weight, hence their use for | | | | unacceptable, when the only way to correct it is for |
| the bodies and disc brakes of all Formula 1 racing and | | | | it to be changed completely. For this reason the |
| many sports cars, as well as for an impressive 94% | | | | service lives of aluminium and PVC windows are |
| of the wings and fuselage of the new Boeing 787, | | | | predicted by independents to be less than half that |
| scheduled for introduction this year (2010). | | | | of GRP. Timber, of course, requires regular and |
| Building products, which have successfully used this | | | | expensive maintenance throughout its life, which is |
| technology in UK, have been, most notably, the GRP | | | | enormously unsustainable and makes it the most |
| residential 'composite' door, introduced in 1987 and | | | | expensive whole life cost option of them all, typically |
| which now dominates social housing - and a variety | | | | twice the cost of GRP over 30 years. |
| of moulded roof canopy structures. These products | | | | New innovative materials are always greeted with |
| use, either, high pressure flat pressing for door skins, | | | | caution in the Building Industry and GRP is no |
| or, hand lay-up moulded assembly for the | | | | exception! However, the benefits to those who have |
| manufacture of more complex shapes. This was the | | | | had the confidence to investigate it and use it |
| extent of the manufacturing options until more | | | | first-hand, are immense and have been proven many |
| recently, although a continuous manufacturing | | | | times over. So, thank you to Dr Baekerland, who |
| process has long been sought after, to produce | | | | would be delighted at how his early discovery has |
| unlimited lengths of shaped profiles that can be cut | | | | been developed and, today, able to come to the aid |
| to any dimension and thus minimise wastage. This | | | | of those seeking to reduce carbon emissions and |
| 'pultrusion' process was developed in North America, | | | | thus help to slow the rate of climate change. |
| in the 1980's and enabled the availability of GRP | | | | |