Great to see a full sample window and a corner cross section.
GRP goes under several names:
GRP = Glass Re-enforced Plastic = Fiberglass Reinforced Plastics (FRP) = composite
- The GRP is pulled through the pulleys etc. The even and controlled drying out / curing of the GRP means that if damaged (like a GRP surf board) you don’t exposed glass fibres and un-cured resin that can give osmosis star crazing.
- Maintenance needs (super low, just the metal hardware)
- Lifespan (75 years plus, ease of replacing any glazing units that fail).
- Outlasting PVC, Alu clad wood etc. means ends up being cheaper and lower environmental impact as one set of GRP windows and doors = 1+ sets if PVC, wood or Alu clad wood.
- End of life recycling (theoretically possible, but nobody is currently doing this, but how much are Alu clad timber frames etc. properly recycled? Sadly, few if any).
- In Europe their seem to be only 3 factories who can recycle GRP. ERCOM in Germany, MCR in France and Miljotek in Norway. They struggle to find markets for their recyclate.
- Current end of GRP life is landfill (relatively cheap), incineration (50% becomes ash which is landfilled) or into cement production (energy from incineration and ash into the cement).
- There is currently no market value for waste composite in the UK as recyclate. Other than a few firms which grind production waste and use it as filler. At the moment the recycling cost is too high. As the price of landfill goes up or the raw material price goes up, this could change.
- Outlasts alternatives, so over 30 years apparently cheaper than PVC.
- Wood required re-painting every 3 or so years. Factor that cost in and the shorter life and more expensive.
- Initial outlay can be lower. Current GRP quote from Pultec is a LOT less than the quote for Alu Clad wood doors and windows (that don’t have as good a thermal U-value !)
Photo of the sample window brought to the meeting. Focusing on the handle!
Pultec GRP Windows Specification
- Triple glazed
- Krypton fill
- Argon has a thermal conductivity 67% that of air,
krypton has about half the conductivity of argon.
- Krypton is an inert gas, heavier and denser than Oxygen. It is colourless, odourless, tasteless and harmless. The Earth’s atmosphere is made up of approximately 0.00011% krypton. It is obtained by separating air into its constituent components by fractional distillation.
- Argon has a thermal conductivity 67% that of air,
- Warm edge spacers
- Double Low ‘E’ softcoat.
- This metal coating reflects heat (keeping heat in during the winter and sun heat out in the summer)
- Soft coat Low E glass is more reflective than hard coat Low E glass.
- Soft coat Low-E glass, involves the application of silver, zinc or tin to glass in a vacuum. The glass enters a vacuum chamber filled with an inert gas which is electrically charged. The electricity combined with the vacuum allows molecules of metal to sputter onto the glass. The coating is fairly delicate or “soft.”
- A “hard-coat” low-e application is done when the glass is in a molten state. The process results in a durable coating that can be used on storm doors and windows. A “soft-coat” low-e application happens after the glass is made. The soft coat is more efficient at reflecting heat energy, but also more delicate. This low-e coating always faces the insulating airspace in double or triple-pane glazing. Since soft coat emissivity can oxidize when exposed to air, argon or krypton gas is often used in the insulating airspace to help preserve the coating.
Summary of advantages of GRP Windows:
This summary is from an email from YPRADO.
- “A” Rated in BRE Green Guide to Specification for Sustainable Construction (UK)
- BREEAM: 4½ extra credits potentially available.
- 22% is from a recycled source. Product 100% recyclable upon disposal.
- 65% glass content, (silica/sand, the most abundant substance on the planet)
- Sensitivity Report (emailed to me), quantifying environmental credentials by sustainability consultants Price & Myers, London.
- “U” values 0.8 – 1.6 “U” W/M2K on the total window. 1.2 U value achieved with double glazing only, no need for triple (thus cheaper and less wear on hinges)
- I’ve asked for triple glazing, so even better U Values.
- Low embodied energy in pultrusion manufacturing process (confirmed by GreenBuildingForum threads, where there was however some discussion regarding the embodied energy of the raw materials).
- Twice the strength to weight ratio of mild steel – cannot deform like aluminium
- 75 years service life + 12 year Warranty.
- Negligible coefficient of expansion, even if coated black
- Performance unaffected in temperatures between +100C and -100C
- Impervious to UV degradation
- But the paint will slowly fade in colour.
- The paint is over the white GRP frames. The paint chemically bonds to the GRP (unlike paint on Aluminium frames).
- Impervious to salt corrosion and sea water.
- Impervious to the harshest weather – effectively, indestructible by natural forces.
- Robust! – used on Young Mental Offenders Secure Units – Meets MOD anti-terrorist glazing requirements – DMG2 “Normal”
- Secured by Design accredited – Police preferred specification – including both BS 7950 and PAS 23/24
- Zero maintenance required – however, surface damage, structural repairs and re-painting can be easily undertaken on site, with no consequential liability for future applications.
- You can just use surf board resin or similar.
- High resistance to impact damage – will not deform under impact.
- Highly price competitive with aluminium and timber/alu composite windows.
- Any RAL colour available (200+ options)
- Impervious to all chemicals and most acids.