Internorm is Europe’s largest international manufacturer of energy-efficient windows and doors. Founded in Austria in 1931, the company sells its products through more than 1,300 distribution partners across 21 countries and holds the leading market share position in the European premium glazing sector. Internorm windows and doors are manufactured to strict European standards for thermal performance, acoustic insulation, security, and durability.
In Ireland, ThermoGlaze is an authorized Internorm windows and doors supplier and installer, operating from two Dublin showrooms – one in Swords and one in Rathgar.
Why Is Internorm the Most Popular Window Brand in Europe?
Internorm’s dominance across Europe comes down to four core reasons:
- Certified energy performance – U-values as low as 0.6 W/m²K, with Passive House certified products across multiple ranges
- Three frame material options – uPVC, timber-aluminium (alu-clad), and aluminium, covering every home type
- Built-in security – RC2 burglar resistance class as standard on all products
- Design range – over 200 RAL colour options, woodgrain finishes, and dual-colour configurations
No other manufacturer in Europe combines all four at scale, which is why Internorm has held the top position in window and door market share for over two decades.
Internorm Windows and Doors: Key Features Explained
Thermal Efficiency – What the Numbers Mean?
A U-value measures how much heat passes through a window or door per square metre. The lower the number, the better the insulation. Standard double-glazed windows typically achieve 1.4–1.6 W/m²K. Internorm windows achieve as low as 0.6 W/m²K on their triple-glazed alu-clad range – more than twice as efficient.
For Irish homeowners, this matters because:
- A lower U-value means less heat escapes, reducing your gas or oil consumption
- Better U-values directly improve your BER (Building Energy Rating) score
- Many Internorm products meet the threshold required for SEAI window and door grants in Ireland
Security – What RC2 Means?
RC2 is a European burglar resistance classification that indicates a tested level of resistance against forced entry using specified tools. RC3 offers a higher level of tested resistance and is available on selected Internorm systems.
Frame Materials – Which One Is Right for Your Home?
| Frame Type | Interior Finish | Exterior Finish | Best For |
| uPVC | White or colour | White or colour | Standard residential, mid-range budget |
| Timber-Aluminium (Alu-Clad) | Natural wood | Powder-coated aluminium | Period homes, conservation areas |
| Aluminium | Powder-coated | Powder-coated | Modern builds, slim sightlines |
Internorm Window Styles Available in Dublin
ThermoGlaze supplies and installs the following Internorm windows across Dublin:
| Window Style | Opening Mechanism | Suited To |
| Casement | Outward side-hung | Most Irish homes, traditional and modern |
| Tilt & Turn | Inward tilt or full turn | Apartments, modern builds |
| Flush Glaze | Fixed or opening, flush frame | Contemporary architecture |
- Casement windows – the most common choice for standard Dublin houses
- Tilt and turn windows – dual-function, popular in apartments and new builds
- Flushed glaze windows – modern aesthetic, flush with the outer frame
Internorm Doors Available in Dublin
Internorm manufactures both windows and doors, with the same thermal and security performance across both product lines. The Internorm front door range covers both contemporary and traditional styles, with triple-glazed sidelights available.
For larger openings, ThermoGlaze also supplies:
- Bi-fold doors – fold-back panels that open up an entire wall
- Patio doors – standard sliding door access to outdoor spaces
- French doors – classic double-door, hinged outward
How Does Internorm Compare to Standard Windows?
Internorm windows outperform standard windows on thermal efficiency, security, acoustic insulation, and lifespan. Here is a direct comparison:
| Feature | Standard Windows | Internorm Windows |
| Typical U-Value | 1.4–1.6 W/m²K | As low as 0.6 W/m²K |
| Glazing | Double (typical) | Triple glazing available |
| Frame Materials | uPVC or aluminium | uPVC, timber-alu, aluminium |
| Security Class | Basic locking | RC2 standard, RC3 available |
| Passive House Certified | Rarely | Available across multiple ranges |
| Colour Options | Limited | 200+ RAL colours + woodgrain |
| Expected Lifespan | 15–20 years (uPVC) | 30+ years across all materials |
Are Internorm Windows SEAI Grant-Eligible in Ireland?
In many cases, yes. Ireland’s SEAI (Sustainable Energy Authority of Ireland) provides grants for window and door upgrades that meet minimum U-value thresholds. Internorm’s triple-glazed products frequently meet or exceed these thresholds.
To confirm grant eligibility for your specific project, speak directly with the ThermoGlaze team. Our advisors can cross-reference your existing BER rating, proposed Internorm specification, and current SEAI grant criteria before you commit to anything.
📋 Request a free quote and grant eligibility check
Are Internorm Windows Suitable for Period Homes in Dublin?
Yes – Internorm’s timber-aluminium (alu-clad) range is regularly specified for Georgian and Victorian properties across Dublin. The woodgrain timber interior finish matches the aesthetic of older homes, while the powder-coated aluminium exterior requires minimal maintenance. Dual-colour configurations – where the interior and exterior are different colours – are standard.
For period homes in Dublin conservation areas such as Rathgar, Donnybrook, or Drumcondra, the vertical slider window in an alu-clad frame is the most commonly specified Internorm product. Always check with your local authority before replacing windows in a protected structure.
ThermoGlaze: Dublin’s Authorised Internorm Installer
ThermoGlaze is an authorized Internorm supplier and installer based in Dublin, Ireland. We supply and fit premium windows and doors to Dublin homeowners and builders, operating from two showrooms where Internorm products are on display.
We cover new builds and full window and door replacements across Swords, Rathgar, Clontarf, Donnybrook, Drumcondra, Raheny, Blanchardstown, and all Dublin postal districts.
Visit Our Dublin Showrooms
See Internorm windows and doors in person before you decide. Our showroom team can walk you through every frame type, colour finish, glazing option, and hardware choice.
Swords Showroom
Unit F2, Swords Enterprise Park, Feltrim Road, Drinan, Swords, Co. Dublin, K67 WF72
Rathgar Showroom
68 Rathgar Avenue, Dublin 6, D06 KN53
📞 Call: 01 912 0600
🌐 Website: ThermoGlaze.ie
Conclusion
Internorm holds the top position in European window and door market share because the products genuinely deliver – on thermal performance, security, design range, and longevity. For Dublin homeowners, that means better BER ratings, lower heating bills, potential SEAI grant eligibility, and windows that last well beyond standard alternatives.
ThermoGlaze brings the full Internorm range to Dublin, with two showrooms, a local installation team, and advisors who can guide you from specification through to final fit. Whether you’re replacing one window or fitting out a new build, we can help you get it right.
FAQs
1. What is Internorm?
Internorm is Europe’s largest international manufacturer of energy-efficient windows and doors, founded in Austria in 1931 and selling across 30+ countries.
2. Who sells Internorm windows in Dublin?
ThermoGlaze is an authorized Internorm supplier and installer in Dublin, with showrooms in Swords and Rathgar. Call 01 912 0600.
3. What U-value do Internorm windows achieve?
Internorm windows achieve U-values as low as 0.6 W/m²K on their triple-glazed alu-clad range – significantly better than the 1.4-1.6 W/m²K typical of standard double-glazed windows.
4. Are Internorm windows eligible for SEAI grants in Ireland?
Many Internorm products meet or exceed the U-value thresholds required for SEAI retrofit grants. Speak to ThermoGlaze to confirm eligibility for your specific project.
5. What frame materials does Internorm offer?
Internorm manufactures in three frame materials: uPVC, timber-aluminium (alu-clad), and aluminium – covering a wide range of home types, planning requirements, and performance needs.
6. Are Internorm windows suitable for Georgian or Victorian homes in Dublin?
Yes. The timber-aluminium alu-clad range with woodgrain interior finish is regularly used in period properties across Dublin, including in conservation areas.
7. What security standard do Internorm windows and doors meet?
All Internorm products come with RC2 burglar resistance class as standard. RC3-rated products are available for higher security requirements.
8. How long do Internorm windows last?
Internorm products are designed for long-term performance and durability, using high-quality materials and advanced manufacturing processes, well above the 15–20 year typical lifespan of standard uPVC windows.
9. Can I get Internorm windows in different colours?
Yes. Internorm offers over 200 RAL colour options, woodgrain finishes, and dual-colour configurations – different internal and external colours on the same unit.
10. How do I get a quote for Internorm windows in Dublin?
Call ThermoGlaze on 01 912 0600, visit either showroom, or submit a quote at ThermoGlaze.