Pilkington Spacia™

Pilkington Spacia™


The width of single glazing. The warmth of double glazing.

Our revolutionary Pilkington Spacia™ vacuum glazing technology provides unrivalled thermal performance in an ultra-thin unit that fits seamlessly into listed and conservation properties. This innovative unit allows the character of the property to be retained as it can be used with the original frames. It can also be used as secondary glazing and where aesthetics are important in a new or modern property.

How It Works

Pilkington Spacia™ consists of an outer pane of low-emissivity glass and an inner pane of clear float glass, with a vacuum rather than air or gas between the two panes of glass. The result is excellent thermal performance from a unit only fractionally as thick as a standard doubled glazed unit.

Below are some images of recent projects at Repton school, Derbyshire, and Maltsters Tap, Shropshire (Both courtesy of Gowercroft Joinery).

To find out more about these projects click HERE

Pilkington Spacia™ Gallery

 White cottages with Pilkington Spacia™  Repton school with Pilkington Spacia™
Maltsters Tap, Shropshire Maltsters Tap, Shropshire

Watch our latest Pilkington Spacia™ Video

Supplier Information

For more information on our Pilkington Spacia™ suppliers who offer a range of supply & install services and the manufacture of bespoke Timber Windows  -  Click the Logos below:

Areas Covered:
Scotland & Northumberland

Areas Covered:

Areas Covered:
Central England



Gowercroft Joinery

Award winning timber windows and doors of exceptional quality. We are a premium quality, full service, UK manufacturer of joinery products with extended guarantees. Designing, manufacturing and installing windows, doors, garden rooms and internal fittings for new build, renovation and heritage projects.

Our Heritage window and door ranges featuring Pilkington Spacia™ glass have won and been shortlisted for a number of national awards, as well as being installed in significant listed buildings across the country.

Installation Service Offered: Full windows and doors featuring Pilkington Spacia™ glass. Glass and glazing is provided on a supply only basis.
Installation Area covered: Nationwide
Supply available: Commercial and Domestic
Supply area covered: Nationwide
Website: www.gowercroft.co.uk/
e-mail: info@gowercroft.com
Telephone: 01773 300510

Name of Distributor: ENERGLAZE UK Ltd

Head Office: Suite 40, Edwin Foden Business Centre, Moss Lane, Sandbach, Cheshire, CW11 3AE

London Office: 601 International House, 223 Regent Street, London W1B 2QD

Services: ENERGLAZE UK Ltd specialise in retrofitting energy-efficient glazing products into existing window frames. To date we have retrofitted over 5000 homes with Pilkington products. We are the current agents for Pilkington Spacia™ and specialise in retrofitting this ultra-thin double-glazing into existing timber sash windows.

Areas covered: UK Nationwide
Supply: We offer a supply only and or a supply and install service throughout the UK
Website: www.energlaze.co.uk
e-mail: info@energlaze.co.uk
Telephone: 0845 8621801 or 0161 5050626


ENERGLAZE specialise in retrofitting energy-efficient glazing products into existing window frames. To date we have retrofitted over 5000 homes with Pilkington products. We are the current agents in Ireland both North and South for Pilkington Spacia™ and have successfully completed over 300 installations into existing timber sash windows.

Installation Area covered: Republic of Ireland and Northern Ireland.
Supply available: We offer a supply only and supply and install service throughout the island of Ireland.
Website: www.energlaze.ie
e-mail: info@energlaze.ie
Telephone: Rep of Ireland +353 (01) 9011635 Northern Ireland +44 (0)2890995666

WM Mallen Joinery

Wm Mallen Joinery, established in 1983, based in Town Yetholm in the Scottish Borders, is predominately a joinery business that specialises in sash and case windows. Over the last 20 years, Wm Mallen joinery has built up the business to focus on the refurbishment and replacement of sash and case windows alongside the development of a draft proofing system which can be used in conjunction with the windows and doors.

Website: wmallenjoinery.co.uk/
e-mail: wmallenjoinery@btconnect.com
Telephone: 01573 420 452

Grosvenor Restoration Ltd

Specialist in the renovation and performance upgrading of period sash and casement windows
Full installation service in Staffordshire, Shropshire and the West Midlands
Installation service only available for Domestic Customers
Supply only service from a line between Staffordshire & Midlands and North London
Supply only available for both domestic & commercial customers

Website: www.grosvenorrestoration.co.uk
e-mail: tony.grl@outlook.com
Telephone: 07830 095189

Glass Services

Established in 1995; Glass Services has been grown to become one of the largest independent processors and distributers of flat glass products in the south east of England.

We work closely with the joinery and restoration trades to supply high quality glass products and are proud to offer Pilkington Spacia™ as an industry leading solution to thermal performance in heritage glazing.

Supply available: Commercial and Domestic
Supply area covered: UK - Kent, Sussex and London, Europe - France and Belgium
Website: www.glassservices.co.uk
e-mail: sales@glassservices.co.uk
Telephone: 01233 632245

See what our suppliers have to say

Tony Dee, owner and director of Grosvenor Restoration, said:

“The technology behind Pilkington Spacia™ helps us to deliver authentic sash windows with all the benefits of modern glazing.

“Being 6mm thick thanks to vacuum glazing technology, Pilkington Spacia™ allows us to create windows for period and listed buildings that delivers excellent thermal insulation while still fitting into original slim profiles.

“I always highly recommend the product. It performs to a high standard and often outperforms thicker and heavier double glazing. 

“Slim window profiles and protected building features when working with listed properties mean fabricators are often restricted to single glazing - contributing to greater heat loss and less sound insulation. But with Pilkington Spacia™, our customers are enjoying less noise transmittance, warmer homes, and slashed energy bills - something they thought were the costs of living in a period building.”

Andrew Madge, managing director of Gowercroft Joinery, said

“Pilkington Spacia™ is an integral part of our new Heritage range of windows, which has been developed specifically for the listed property and conservation market.

By combining this ultra-slim vacuum glazing with our traditional joinery and detailing in Accoya® timber and our specially developed protective paint finish, we can offer our customers a truly unique solution which delivers the best of all worlds – that’s to say fully factory fitted, sustainable and low maintenance windows, with excellent thermal and acoustic efficiency that look just like the single glazed windows of the past!

"Thanks to this unique combination of innovation and craftsmanship, historic buildings can now benefit from windows made to the highest modern performance standards without compromising any of their traditional appearance."



The world’s first commercially available vacuum glazing. This extremely thin glazing can be fitted in old style fine frames, maintaining the original appearance of older traditional buildings whilst providing good thermal insulation.

  • Thermal performance equal to or better than that of most low-e double glazing but in the same thickness as single glass
  • Suitable as a replacement for single glazing in old frames, retaining the appearance of historic buildings and meeting the requirements for conservation areas
  • Four times better thermal insulation than single glazing
  • Suitable for other applications where use of thinner, low-weight glazing is desirable, such as sliding box sashes, secondary glazing, or as part of a triple glazed ‘super-window’
  • Pilkington Spacia™ achieves higher levels of sound insulation than conventional glazing
  • Proven solution; installed successfully in the UK and used in Japan for over a decade
  • Offers reduced levels of internal condensation compared to single glazing




Are there glazing guidelines?

Yes, please click on the Brochures tab and download the Handling and Glazing guidelines. At a nominal thickness of 6.2 mm, Pilkington Spacia™ is slimmer than conventional double glazing units which means there are more glazing options and opportunities.


Can I see a sample?

Yes, samples are available however, since they are rather expensive, we ask for details about your project. The best way to obtain one is to email us via our Contact form


Can it be made to any size or shape?

Many shapes can be produced, but to do so two straight edges forming a right angle are required. Please see the examples below.

The size limits are: 

Maximum 1350 x 2400 mm Clear
Maximum 1200 x 1800 mm for Pilkington Spacia™ Opaque
Minimum 335 x 120 mm


Can it be used to comply with building regulations Approved Document K - low level glazing?

Pilkington Spacia™ does not have a classification to BS EN 12600 for pendulum body impact resistance, so cannot be used in critical locations where a safety glass is required. It can however have a suitable safety film applied or be modified on site to achieve a classification in accordance with BS EN 12600.

For areas where Pilkington Spacia™ has had impact resistant films applied by a third party, then extra care should be taken when handling and cleaning the glass to avoid damaging the permanent protective film.



Can it be used to comply with current building regulations concerning energy efficiency?

Yes. As part of a SAP calculation for new dwellings, Pilkington Spacia™, in an appropriate frame, can meet or improve upon the  minimum elemental standards for fabric performance – sometimes referred to as 'backstop' values - of window U-value of 2.0 W/m²K or lower value of 1.6 W/m²K proposed for the next revision of Part L. Pilkington Spacia™ can also be used for replacement windows that require a WER (Window Energy Rating) of band C or better or a maximum window U-value of1.6 W/m²K. Certain buildings that are restricted in their glazing options have special consideration for energy efficiency. They can benefit from using Pilkington Spacia™ where traditional glazing is inappropriate and single glazing does not provide the thermal comfort of a modern home.


Can Pilkington Spacia™ be putty glazed?

Yes. It is compatible with most glazing compounds with the exception of those containing acetic acid.

Traditional putty may be used to glaze the majority of the Pilkington Spacia™ product range, but must not be used with Pilkington Spacia™ Shizuka laminated products.


Can you see the spacer bar?

Pilkington Spacia™ vacuum glazing doesn’t use spacer bar technology, and therefore can be easily glazed into steel, wood and secondary glazing window systems, both new or old with a similar visual appearance to that of single glazing.


Does the product come with a warranty?

Yes. The standard warranty is 10 years.


How do you stop the 2 panes of glass touching each other?

There is a grid of micro spacers within the unit keeping the glass surfaces apart. They are 0.5 mm diameter and 20 mm apart, and when viewed in transmission at a distance of 2-3 metres they become imperceptible.


How does the performance of the product compare with other Pilkington low-e products?

Pilkington Spacia™ is far from a compromise on performance. Just compare the figures in this table, which shows that it is four times more thermally efficient than single glazing. 

Product Nominal thickness (mm) Light Transmittance  Light Reflectance  Centre Pane Ug-value [W/m²K] Solar Total Solar Heat Transmittance (g-value)
Direct Transmittance  Reflectance 
Single Glazing
6 mm Pilkington Spacia™ 6.2 0.78 0.13 1.1 0.62 0.17 0.67
6 mm Pilkington Spacia™ Cool 6.2 0.70 0.23 0.9 0.48 0.34 0.53
Traditional Glazing options
4 mm Pilkington Optifloat™ Clear 4 0.90 0.08 5.8 0.85 0.08 0.87
4 mm Pilkington Optifloat™ Clear
/ 16 mm air /
4 mm Pilkington K Glass™
24 0.75 0.18 1.7 0.62 0.16 0.73

Max size: 2400 mm × 1500 mm. Min size: 335 mm × 120 mm. Pilkington Spacia™ Opaque max size: 1800 mm × 1200 mm.
The above table is determined in general accordance with EN 410 and EN 673 with the exception of the U value for Pilkington Spacia™ which has been measured in accordance with EN 674.


How long does it take from placing and order to delivery?

The standard lead time is 12-14 weeks; a 4-5 week delivery is available via air freight but this does obviously increase the cost considerably.


Is there an obscure version?

Yes, Pilkington Spacia™ Opaque is a sandblasted version with the obscure facing into the cavity. The maximum size is 1800 x 1200 mm and the obscure version is currently the same price as the clear version.


Tell me about the air extraction point

Pilkington Spacia™ uses vacuum technology and the point at which air is removed is covered by a small cap on every unit. The black protection cap is 12mm in diameter and set 50mm in from two edges of the glass and should not be removed.  The cap is not intrusive and tends not to be noticed once glazed. Although the cap comes in black as standard, silver is also available on request.


What will it cost?

The price is available on application. There is a minimum area charge 0.3m² per pane. For orders above 4m², and as an approximate guide the cost will fall between £200 - £300m² depending upon volume, sizes and quantities, as packaging and delivery costs need to be included. Please contact the Pilkington Spacia™ dealerships with any enquiry as these costs can vary. Note - the smaller the order the more expensive the glass per m², as small orders attract a disproportionate level of transport costs


What acoustic performance does this product provide?

A comparison of the sound insulation data of Pilkington Spacia™ compared to that of single and double glazing is provided in the table below: 

Product Rw (C; Ctr) dB  Improvement due to Pilkington Spacia™ (dB) 
6.2 mm Pilkington Spacia™ 35 (-1; -3) N/A
Single glazing 
4 mm Float Glass 29 (-2; -3) +6
6 mm Float Glass 31 (-2; -3) +4
8 mm Float Glass 32 (-2; -3) +3
10 mm Float Glass 33 (-2; -3) +2
12 mm Float Glass 34 (0; -2) +1
Double glazing
4 mm Pilkington Optifloat™ - 16 mm argon - 4 mm Pilkington Optifloat™ 31 (-2; -5) +4
6 mm Pilkington Optifloat™ - 16 mm argon - 4 mm Pilkington Optifloat™ 34 (-2; -5) +1

Note: The values for single glazing are generally accepted values for generic products taken from EN 12758. They are conservative values that can be used in the absence of measured data. The values for Pilkington Spacia™ and insulating glass units have been measured in accordance with EN ISO 10140 and Rw (C; Ctr) determined in accordance with EN ISO 717-1.