Overview
What goes into a score
Each quote is assessed across five categories, each scored out of 100 points. The overall score is the unweighted average of all five category percentages — every category carries equal weight.
Grade thresholds
Quality factors
Product, guarantees & installation
Glass & frame quality100 pts
The physical specification of the windows or doors themselves — the most lasting impact on comfort, energy bills, and security.
Guarantees & aftercare100 pts
A guarantee is only as good as the company standing behind it. We look at length, coverage, and the company's ability to honour it long-term.
Installation quality100 pts
Even the best windows underperform if poorly fitted. We assess who does the work, how they are trained, and what the process involves.
Value factors
Price & transparency
Value & price benchmarking100 pts
Price is not scored in isolation. A lower price on a weaker spec is not good value. A higher price on a comprehensively specified product may be fully justified.
Where the benchmarks come from
Price benchmarks are derived from Scottish market data covering typical window and door installations. They are segmented by product type (casement, sash, bifold, composite door, etc.) and adjusted for quantity.
Critically, the benchmark is spec-aware: a quote scoring ≥75% on product quality is assessed against a higher price band, reflecting the reality that better-specified products cost more to manufacture. This prevents penalising quality suppliers and rewards transparency.
Trust factors
Company credibility
Company trust & credentials100 pts
Third-party signals that indicate a company's legitimacy, longevity, and commitment to quality.
What "Not stated" means
Where a quote does not mention a parameter, it receives zero points for that criterion. Omission is treated as a signal: a company confident in its product will state the specification. One that doesn't is either unsure, or hoping you won't ask.
The result page always shows which criteria were not stated so you can use this as a starting point for questions before signing anything.
Sources & references
Where the logic comes from
- Scottish Building Standards — Technical Handbook (Domestic), Section 6: Energy
- British Standards: BS EN ISO 10077 (thermal performance of windows), PAS 24 (enhanced security)
- BFRC (British Fenestration Rating Council) — Window Energy Rating classification
- BSI, BBA, and ISO 9001 accreditation frameworks
- Scottish market pricing research — anonymous survey of quotations, 2024–2025
- Consumer Rights Act 2015 — guidance on guarantee and warranty obligations