Certass vs Fensa: Which Certification Body is Right for Your Windows?

certass vs fensa


When installing new windows in your home, you want assurance that they meet certain standards for safety, security, and energy efficiency. To provide this assurance, window installers can become certified by organisations like Certass or Fensa. Understanding the difference between Certass and Fensa certification can help guide your decision when choosing a window installer. But what’s the main difference between these two industry leaders in window installer certification? Certass vs Fensa – we’ll outline the key distinctions so you can determine which certification provides the standards assurance you need for your new windows.

What is Certass?


Certass was launched in 2013 by the Glass and Glazing Federation, a trade association for glazing companies. It offers certification specifically related to replacement windows and doors. Over 4,500 installers are registered with Certass across the UK.


Certass audits window installations to confirm they meet building standards for aspects like fire safety, ventilation, thermal efficiency and secure fixing. Certified installers can provide an insurance-backed guarantee.


Registration and certification fees depend on company size, ranging from £420-£3,210 per year. Certass takes a percentage of the contract value as an additional fee.

What is Fensa?


Fensa, which stands for Fenestration Self-Assessment, was created in 2002 by the Glass and Glazing Federation along with other industry bodies. It focuses solely on thermal efficiency requirements. Over 7,000 firms are Fensa-registered.


Fensa ensures windows meet insulation and energy conservation standards. Certified installers can issue certificates proving compliance with building regulations. Fensa also operates a consumer complaints resolution process.


Fensa registration costs a one-time fee of £465-£630 plus an annual fee of £185-£345 depending on company size. Additional charges are based on the number of certificates issued.

Key Differences

Industry Recognition

Fensa enjoys wider industry and consumer recognition since it has been around longer. All Fensa-certified installers are deemed to satisfy building regulations. With Certass, additional approvals may be needed.

Auditing Process

Fensa operates on self-certification with random audits. Certass physically audits a sample of installations from each registered firm on an annual basis.

Complaints Process

If issues arise, Certass investigates complaints about specific installers. Fensa examines wider concerns about potential non-compliance with regulations.

Making a Decision

When choosing between Certass and Fensa, consider:

Consider Your Needs

If you want certification encompassing all building regs for windows, not just energy efficiency rules, Lean towards Certass.

Compare Costs

The overall fees charged by each organisation may differ based on your firm’s business. Review fee structures carefully.

Read Reviews

Check reviews and feedback from other installers on their experiences working with Certass and Fensa.


While Fensa offers longer-standing name recognition, Certass provides more comprehensive standards auditing tailored to windows and doors. Certass also investigates customer complaints related to specific installations while Fensa examines wider regulatory breaches.

Final Thoughts

Consult with window providers you trust about whether they carry Certass or Fensa certification. Weigh up the benefits and costs of each scheme based on your individual needs. Either option can provide credibility and industry validation.


What are the key dates for Certass and Fensa?

Certass launched in 2013 while Fensa was created in 2002. Both are administered by the Glass and Glazing Federation trade association.

How much does it cost to be certified?

Certass fees include annual registration charges and additional percentages based on contract values. Fensa charges involve one-time and yearly fixed fees plus per-certificate costs.

What do they check when auditing installers?

Certass audits a range of building standards including safety, ventilation and energy efficiency. Fensa focuses specifically on thermal performance and energy rules.

Who handles consumer complaints?

Certass investigates issues raised about individual installation firms. Fensa examines wider problems concerning potential non-compliance.

Which is better recognized in the UK industry?

Fensa currently enjoys higher recognition since it has been certifying window installers for longer than Certass.

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