Are you wondering how to lower your energy bills? Choose new windows containing PLANITHERM – proven to be the most energy-efficient window glass available in the UK

Laminated Glass

PLANITHERM is a new generation of energy saving window glass that uses advanced coatings to retain more internal warmth whilst capturing free energy from natural daylight.

Using PLANITHERM, you can have A rated windows installed for around the same cost as less energy efficient windows. A staggering 26% of all domestic heat loss escapes through the windows*. Installing A rated energy efficient windows can save you up to 28% per year on your heating bills compared to traditional windows and frames.

If you are planning to replace your existing single glazed or double glazed windows, and you want the best possible choice for energy savings, ask us for PLANITHERM.

PLANITHERM products use a special coating to reflect heat from domestic heat sources back into the room, rather than allowing it to escape outside through the windows. In addition to this, the coating allows free heat and light from the sun to pass through the glass, warming the room and further contributing to the energy efficiency of the windows and helping to reduce your energy bills.

This combination of unrivalled thermal insulation with high solar heat gain makes PLANITHERM the most energy efficient window glass available and the best possible choice for energy savings.

If you install windows with PLANITHERM your home will be lighter, brighter, warmer and more energy efficient thanks to the advanced thermal insulation of PLANITHERM.

Free Solar Heat Gain – PLANITHERM has a unique coating which captures free energy from natural daylight to heat the home.

Thermal Insulation – The coating reflects heat back into the room, helping to keep the room warmer and reduce heating bills.

Optimal Energy Ratings – As PLANITHERM is the most energy-efficient glass available, A-rated windows can be achieved using energy-efficient frames.

Haze and Tint free windows – PLANITHERM maximizes natural light entering the home without the tint or haze effects associated with some other double-glazed windows.

Eliminates Condensation – PLANITHERM helps to reduce draughts and cold spots around windows and helps to virtually eliminate internal condensation.

For further information, ask us about PLANITHERM or visit

* Source: Energy Saving Trust

Capable of withstanding an attack.

Sheets of glass are bonded – or laminated – together with a layer of polymer film (PVB) in between. By using heat and pressure, air bubbles are eliminated from the laminate (in equipment called an Autoclave) so that it appears optically as a single sheet. Laminated comes in several different thicknesses and can be used as a form of security. Standard thickness is around 4.5mm, we would advise a minimum of 6.4mm for household security.


Used for areas in need of extra safety, glazed doors and glazing adjacent to doors as standard. Float glass is heated to about 650C in a furnace, then quenched with air jets so that the surfaces are cooled quickly and the inside core more slowly with the surfaces going into ‘compression’ and the core going into ‘tension’.
(Toughened Glass is NOT for security but purely for safety)



‘Low-E’ glass which usually forms the inner pane of a double glazing unit, allows less heat to escape through your windows than ordinary glass. Thanks to a special energy saving coating which lets the sun’s rays through, but reflects heat from fires and radiators back into your home. Also available as laminated, toughened and patterned.

There are several versions of ‘Low-E’ glass:

  • ‘K’Glass – made by Pilkingtons will achieve an energy rating of ‘E’ which is 1.7.
    This is the base of UK Regulations but does not meet EU regulations which is a minimum of 1.5
  • Soft Coat Glass – made by Saint Gobain and has an energy rating of 1.4 which is ‘C’ rated.

‘Low-E’ glass benefits:-

  • make your home more comfortable
  • make your home more appealing
  • help reduce your energy costs
  • reduce sun glare and noise
  • cuts heat gain and loss during warm and cool months
  • lengthens the lifespan of furnishings against fading
  • improves the security and safety of your home (if Laminated Glass is used)

Heat Efficient Windows

  • Radiant heat originating from indoors is reflected back inside, thus keeping heat inside in the winter.
  • Infrared radiation from the sun is reflected away, keeping it cooler inside in the summer.

Hard / Soft Coated Glass
Hard coated ‘Low-E’ products, such as Pilkington K, have been used predominantly in the UK. They are easier to process but have a slight champagne tint which can make white net curtains look discoloured. A better U Value can be achieved with a soft coated glass such as Saint Gobain’s Planitherm, which reduces heat loss further. The product is also much clearer with no visible tint.

Source: The Sunday Telegraph
Date: 15 July 2012
Author: Jeff Howell

Through a Glass Dimly:

Question: Last December we had La Porte French Doors installed.
According to the product specification they are “Factory Glazed with 24mm Toughened Double Glazed Units with low-e glass and Argon gas filled”. Whenever the sun shines on them the glass takes on a dull appearance and looks dirty. There is no indication of condensation at anytime. The manufacturers are coming to inspect the glass but have told us that this is normal given the current regulations covering this type of glass. Is this correct ?

Answer: Yes, that’s right. All new and replacement windows have to conform to the Building Regulations standard for thermal insulation. This means that at least one pane of a sealed unit must be low-emmissiviy (or “low-e”) glass. Low-e glass works by having a coating which reflects heat, but since heat and light are part of the electromagnetic spectrum, anything that reflects heat must also reflect light. That’s why many people notice that their homes appear to be darker following the fitting of new windows. The low-e coating can also make the glass appear hazy or dirty when the sun shines on it at an oblique angle. I’m afraid this is the price you have to pay for the thermal performance.

NOT at Weatherproof Windows, we use a softcoat glass using Planitherm, not a hard coat glass like Pilkington K.

Insulation glass without ‘Low-E’ coating uses air between the panes as a primary source of insulation. As air itself is a good insulator, filling the gap between the glass panes with a low-conductivity gas such as argon reduces conductive and convective heat transfers. This is because the density of the gas is greater than the density of the air.

Argon is the most commonly used fill gas, due to its excellent thermal performance and cost-efficiency in comparison to other gas fills. Argon gas reduces heat loss in sealed units by slowing down convection inside the air space. It is extremely cost-efficient, and works well with ‘Low-E’ coated glazing. Argon and Krypton are colourless, odourless, non-flammable and non-reactive inert gases.

Several techniques are used to fill the IG cavity and all techniques result in a mixture of fill gas and air. It is generally accepted that the IG unit should achieve a 90% fill gas concentration. Over time this concentration will gradually evaporate, at an estimated rate of 0.5 to 1% per year. IG units filled with argon do not degrade significantly until they reach 75% concentration, which means up to 20 years of durability.

A major benefit of IGU is that it is passive, so it does not require a switching-on process to work. Argon gas is a relatively inexpensive option, and quickly produces heat cost-savings that justify its cost.

Krypton is more effective at reducing heat loss, but is roughly 200 times more expensive than argon per unit volume. Because Krypton works best at smaller pane spacings (8 mm), it is often used in triple and quadruple-glazed windows to minimize the overall thickness of the unit.

Other types of gases are used (for example, sulphur hexafluoride, carbon dioxide) to reduce sound transmission, but these gases do not offer the improved thermal performance of the inert gases.

Recent innovations in glass technology have given us “Self Cleaning Glass” which has been heavily promoted as Pilkington “Activ” or Saint Gobain “Bioclean”. These are predominantly used for conservatory roofs or any areas that can be hard to reach for cleaning purposes. The chemical reaction reacts to organic substances which adhere to the glass and activates when rain falls, which helps release the dirt particles. Other glass cleaning chemicals should not be used on this type of glass for cleaning purposes.
We must point out that Self Cleaning Glass is not the same as having a window cleaner.


Did you know that almost half of all the UK’s carbon dioxide emissions come from our buildings and homes?

Windows play a huge role in this. According to the Energy Saving Trust, around 20% of the heat lost from an average home occurs through the windows. The heat lost contributes half a tonne of CO2 per home to the atmosphere and increases fuel bills.

Reduce Heat Loss Through Your Windows
Warm Edge Spacer is approximately 950 times less conductive than aluminium and, as most of the heat loss through a window occurs at the edge of the unit, standard metal spacer bars act as a thermal energy drain allowing heat to escape from your home. Warm Edge Spacer blocks the escape route.

Warm Edge Spacer, is new energy saving technology. Windows with Warm Edge Spacer reduce heat lost through your windows, helping to keep your home warm. Less heat lost also means lower fuel bills and lower carbon emissions.

Reduce Noise & Condensation
There are many other benefits of installing windows with Warm Edge Spacer. It reduces condensation by up to 65%, virtually eliminating the potential breeding ground for bacteria, mould and dust mites that can be harmful to people with respiratory diseases. Warm Edge Spacer also reduces noise transmission by up to 2dB which helps you keep your home an oasis of calm, away from the noise of the outside world.


Many Window companies will be trying to achieve high energy ratings to add to the quality of their overall product range and to offer consumers greater informed choices about the products they offer

Window profiles are part of the story but as glass makes up most of the area in a window and the components used in its construction are critical to achieving good levels of insulation.

Instead of just Centre pane U value the W.E.R is concerned with the heat loss of the whole window.

Therefore a combination of Coated Glass, Low Iron Glass, Warm Edge Technology and gas filling is critical to achieve a good rating.

Energy Saving Recommended Windows:
Just like washing machines and freezers, windows are energy rated by the British Fenestration Ratings Council on a scale of A-G. Windows achieving a rating of C and above are endorsed by the Energy Saving Trust’s Energy Saving Recommended (ESR) scheme and carry the EST’s swing tag logo.

Make sure you ask for windows with the Energy Saving Recommended logo and Warm Edge Spacer inside to ensure the best energy efficiency.


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Technical Information - However you use glass it is essential for safety and performance reasons that it is correctly specified and installed. Common areas of impact risk, where it is recommended that impact safety glass to BS 6206 is installed, include: Glazed doors, Glazing adjacent to doors, Low level glazing, Bathroom areas, Protective barriers, Furniture and cabinets.

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Workmen well equiped and very friendly and polite.

Very well carried out from start to finish checked over and demonstrated to us.
Customer in Hartlepool

01 Dec 2016

Replacement window.

Excellent workmen. Very polite and tidy.
Customer in Tyne And Wear

26 Sep 2016

Replacing back door

Pleasant workers and they did a very good job.
Customer in Hartlepool

30 Aug 2016

2 new doors

Well done.
Customer in Peterlee

26 Aug 2016

Replaced old conservatory roof with new ultra light sea ...

Weather being poor was a nuisance but other than that every ok.
Customer in Hartlepool

08 Apr 2016

6 replacement windows and door locks.

Excellent, clean job.
Customer in Hartlepool

02 May 2016

Carport/Sun room.

We would like to say "Thank you!" for all the hard work carried out on our property. It’s better then we could have imag ...
Customer in Peterlee

01 Mar 2016

Fitting of new window.

Good price and a good fitting. I am very happy with work carried out.
Customer in Hartlepool

26 Jan 2016

New front door, new security locks to french doors and ...

Extremely happy with workers. Good sense of humour and cleaned up the mess. Very high standard of workmanship and finish ...
Customer in hartlepool

03 Nov 2015

Replacement uPVC back door.

Customer in Hartlepool

16 Oct 2015

Replacement side door to garage.

Fitters turned up earlier than expected and completed a professional and excellent job. They were pleasant and tidied up ...
Customer in Hartlepool

18 Aug 2015

Replacement and new garage roof.

Supposed to take 2 days but, took 3 and a half days, due to weather and supply problems.
Customer in Yarm

20 Jul 2015

Patio doors, bathroom windows & En- Suite bathroom wind ...

Great job.
Customer in Sedgefield

27 May 2015

Supply and fitting of composite front door.

Excellent service and workmanship. Very happy with all aspects of the work. Friendly staff and very helpful. Work carr ...
Customer in Hartlepool

03 Feb 2015

Window renewal.

I was highly delighted and over the moon with the job done. Excellent job!
Customer in Cleveland

24 Apr 2015

fitting of 2 exterior doors and 1 panel.

The work was carried out in a professional manner and the finished job is excellent.
Customer in Hartlepool

25 Mar 2015

2 main windows and 1door replaced

Good workmanship, good time keeping. Windows in and out without much mess but lads did clean up afterwards. Fully expla ...
Customer in Horden

04 Mar 2015


Great work.
Customer in Hartlepool

19 Feb 2015

Full security.

This is the 2nd time I have had work done by Weatherproof Windows, I am very pleased. I would recommend to my friends a ...
Customer in Hartlepool

16 Feb 2015

New door and windows to porch.

Weatherproof Windows were professional from the start they done exactly what I wanted. The work was completed to a very ...
Customer in Hartlepool

19 Dec 2014


Very pleased with the work I had done, absolutely marvellous, I would 100% recommend.
Customer in Grosmont

31 Dec 2014

Fitting 4 windows and a door

2 fitters arrived 15 minutes late, but worked non-stop for 61/2 hours.
Customer in Customer in


Fitting of composite front door.

I am really pleased with the work carried out, they were really professional too.
Customer in Hartlepool

31 Oct 2014

A job well done within the two day schedule.

Due to staff shortage, the installation of windows did not begin on Monday, the day agreed, but next day, Tuesday. Very ...
Customer in Hartlepool

03 Dec 2014

Convert conservatory roof from glass to Guardian System ...

Thoroughly impressed with the way the job was done and the attitude of the people who did the job. Overall score would ...
Customer in HARTLEPOOL

20 Oct 2014

New front door.

Excellent work, looks beautiful.
Customer in Hartlepool

24 Oct 2014

Double glazing.

Friendly, efficient workman. They arrived on time with no complaints.
Customer in Hartlepool

06 Oct 2014

Friendly and conscientious fitters.

This job was carried out with true professionalism from start to finish. Job was done well, I would recommend this compa ...
Customer in Peterlee

03 Oct 2014

Fitted four windows.

Good job.
Customer in Hatrtlepool

01 Oct 2014

Ten windows, French door and composite door fitted.

Job done to a good standard overall I am happy with the work completed. Job was done within a week, I will recommended.
Customer in Hartlepool

24 Sep 2014

New front door.

Customer in Hartlepool

08 Sep 2014

Replacement of two velux windows

Arrived when they said there would.Placed protective covers over everywhere finished job on time and cleaned up after th ...
Customer in Hartlepool

27 Aug 2014

Doors and windows to full house.

Customer in Hartlepool

21 Jul 2014

Replace old back door with new uPVC door

The job was done to a very high standard and the work men were very punctual and tidy their work was impecable could not ...
Customer in hartlepool

15 Jul 2014

Spot on.

Quick, friendly and very efficient.
Customer in Hartlepool

17 Jul 2014

Very good, clean.

Very good, excellent.
Customer in Hartepool

10 Jul 2014

Installation of 3 bay windows and 1 flat window.

A very obliging team who corrected anything we pointed out promptly.
Customer in Hartlepool

25 Jun 2014

Installation of French doors, two double glazed units t ...

The options available were fully explained at the initial survey. After agreeing to the quote, a second survey was carr ...
Customer in Hartlepool

23 Jun 2014

Doors and windows.

Great workmanship, I would highly recommend.
Customer in Wingate

03 Jun 2014

Conservatory roof and guttering removed and replaced.

The tradesman were excellent nothing was a trouble the job was completed to a high standard.
Customer in Hartlepool

02 May 2014

Excellent job.

Excellent job, very clean and tidy.
Customer in Hartlepool

30 Apr 2014

New external window and internal patio door.

The job we had done was really good and professional. We are very satisfied with the cost and workmanship they were also ...
Customer in Hartlepool

28 Feb 2014

New external window and internal patio door.

Very clean professional job done. We are very satisfied with cost and workmanship.
Customer in Hartepool

28 Feb 2014

Replacement Front Door and Rear French Doors (high secu ...

The work was carried out to a very high standard and the workmen were very professional and helpful and done a great job
Customer in Hartlepool

21 Mar 2014

Two doors and a window on the back of house.

Wonderful, excellent , really happy.
Customer in Hartlepool

25 Feb 2014

Replacement window of the back of the house.

Job well done, tradesman did clean up afterwards.
Customer in Hartlepool

24 Feb 2014

New upstairs windows.

Windows were taken out and put in with a minimum of fuss.
Customer in Hartlepool

05 Mar 2014

New front door.

Two very efficient and pleasant lads fitted door, only took two hours. Very pleased with the job.
Customer in Hartlepool

19 Mar 2014

Fitted doors.

Myself and my husband are pleased with the job, highly satisfied with the fitting of the doors.
Customer in Hartlepool

26 Feb 2014

Friendly staff.

I am pleased with the windows, I would recommend them to anyone
Customer in Cleveland

21 Feb 2014

New composite door fitted

Very professional workmen carried out work quickly and efficiently. Left the area clean and tidy and removed the old doo ...
Customer in Hartlepool

22 Jan 2014

Window services.

The work was completed on time, budget and the workmen were polite and friendly.
Customer in Hartepool

08 Jan 2014

Window service.

Great job!
Customer in Hartepool

15 Jan 2014

new garage door.

Initial impression very good.
Customer in Middlebrough

06 Dec 2013

Rubber roof.

Good job, has been done.
Customer in Middlebrough

11 Dec 2013

New soffits, gutters and downpipes.

The work was undertaken quickly, neatly and in two days. They were professional, efficient staff with an excellent serv ...
Customer in Hartlepool

10 Dec 2013

All the front house windows and new front door.

Great job upstairs and down.
Customer in Hartlepool

10 Dec 2013

New double glazed windows.

Excellent job!
Customer in Hartepool

10 Dec 2013

New garage door.

Initial impression, very good.
Customer in middlesbrough

06 Dec 2013

12 windows fitted in 2 days

Pleasant, friendly hard working workforce
Customer in Hartlepool

26 Nov 2013

Supply and install uPVC door to kitchen

The work was carried out on time, to price and the two men doing the work were very pleasant. They kept me informed of ...
Customer in Stockton

13 Dec 2013

Replaced sash windows.

Replaced wooden windows with UPVC ones.
Customer in Hartepool

03 Dec 2013

Bathroom window changed.

Job completed quickly, skilfully and cleanly.
Customer in Hartepool

06 Dec 2013

Renewal of garage roof with rubber.

The work was carried out efficiently and with little disruption, also made sure they tidied up as the work progressed.
Customer in Hartepool

29 Nov 2013

Single Window Fitters.

Efficient, courteous and clean.
Customer in Hartepool

28 Nov 2013

New front door.

I recommend Weatherproof Windows Ltd.
Customer in Hartlepool

03 Dec 2013

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