Choosing between tilt-and-turn, casement, and sash windows can feel like a decision with no clear winner. Each style has different strengths in cost, energy performance, and day-to-day use.
Tilt-and-turn windows are the most energy efficient (U-value 1.0-1.2) but cost 30-70% more than casements. Casements are the cheapest at £400-£700 installed, while sash windows are priciest and least efficient but required for period properties.
- Tilt-and-turn windows achieve the best U-value of 1.0-1.2 W/m²K.
- Casement windows cost £400-£700 installed, the cheapest option.
- Sash windows are most expensive and least energy efficient.
- Tilt-and-turn windows cost 30-70% more than casements.
- Sash windows are often required for period properties in conservation areas.
- The UK window market is dominated by three opening styles casement, sash, and tilt-and-turn
- Casement windows are the most common and cheapest option for standard UK homes
- Tilt-and-turn windows offer the best ventilation and cleaning convenience, at a higher cost
- Sash windows are the traditional choice for period properties but have the lowest energy efficiency
- Quick numbers cost, U-value, and lifespan side by side
- The direct answer tilt-and-turn windows win on energy efficiency and convenience, but casements are cheapest
- Eligibility and certification how to verify a window installer in the UK
For a UK homeowner comparing tilt turn vs casement vs sash, the tilt-and-turn offers the best energy performance (U-value 1.0–1.2 W/m²K) and easiest cleaning, but at a price premium of 30–70% over casements. Casements are the most budget-friendly choice from £400 installed, while sash windows are the most expensive and least efficient, but are often the only option for period properties in conservation areas.
The UK window market is dominated by three opening styles casement, sash, and tilt-and-turn
According to the Department for Energy Security and Net Zero (DESNZ) 2025/26 Housing Stock Data, approximately 65% of UK homes have uPVC casement windows (DESNZ Housing Stock Data, 2026). Sash windows are most common in pre-1919 properties, which make up around 30% of the housing stock. Tilt-and-turn windows account for a growing share, particularly in new-build flats and Passivhaus-certified homes.
Each style offers different trade-offs in energy efficiency, ventilation, cleaning access, and cost. This article provides a direct side-by-side comparison for UK homeowners choosing between the three most common replacement window types.
Casement windows are the most common and cheapest option for standard UK homes
Casement windows are side-hinged and open outward. They are the baseline for most replacement projects in semi-detached and terraced houses.
The typical cost range for a standard 1200mm x 1200mm uPVC casement window, installed with frame and glazing, is £400–£700 per window (Checkatrade cost guide, 2026). Energy efficiency is reasonable. A modern double-glazed casement with a 24mm argon-filled cavity typically achieves a U-value of 1.2–1.4 W/m²K (Glass and Glazing Federation technical data, 2026). A U-value measures how well a window prevents heat from escaping. Lower numbers mean better insulation.
Ventilation is limited to partial opening and restricted by the hinge. The window cannot be left open in rain. Security can be an issue if the window is left ajar. Cleaning requires external access, usually a ladder or a hinged restrictor, unless the window has a reversible sash. Reversible sashes are rare on standard casements.
Tilt-and-turn windows offer the best ventilation and cleaning convenience, at a higher cost
Tilt-and-turn windows open in two modes. In the tilt position, the window is top-hinged inward for secure night ventilation. In the full turn position, it opens inward on side hinges for easy cleaning.
The typical cost for a 1200mm x 1200mm uPVC tilt-and-turn window, installed, is £600–£1,200 per window (Checkatrade cost guide, 2026). Energy efficiency is better than casements due to multi-point locking and compressible gaskets. Typical U-values are 1.0–1.2 W/m²K (Glass and Glazing Federation technical data, 2026).
The tilt position allows secure, rain-safe airflow without opening the window fully. This is a key advantage over casements. The full inward swing means both sides of the glass can be cleaned from inside the room. This is a major selling point for upper-floor windows.
Sash windows are the traditional choice for period properties but have the lowest energy efficiency
Vertical sliding sash windows, also called box sash, are standard in Georgian, Victorian, and Edwardian homes. They are often required in conservation areas or listed buildings.
The typical cost for a standard 1200mm x 1200mm timber sliding sash window, double-glazed and installed, is £800–£1,800 per window (Checkatrade cost guide, 2026). Energy efficiency is significantly worse than casements or tilt-and-turn windows. Even modern double-glazed sashes typically achieve U-values of 1.6–2.0 W/m²K (Glass and Glazing Federation technical data, 2026). The sliding mechanism and less effective seals cause heat loss.
Ventilation is good for natural stack-effect airflow, with both top and bottom sections opening. However, the window cannot be left open securely in high winds, and draughts are common. Cleaning requires external access or a tilt-in sash mechanism, which is an upgrade that adds cost. Traditional sashes are difficult to clean from inside.
Quick numbers cost, U-value, and lifespan side by side
| Feature | Casement (uPVC) | Tilt-and-turn (uPVC) | Sash (timber, double-glazed) |
|---|---|---|---|
| Typical installed cost (per 1200x1200mm window) | £400–£700 | £600–£1,200 | £800–£1,800 |
| Typical U-value (W/m²K) | 1.2–1.4 | 1.0–1.2 | 1.6–2.0 |
| Ventilation modes | 1 (side-hinged outward) | 2 (tilt + turn inward) | 1 (vertical slide) |
| Cleaning from inside | No (unless reversible sash) | Yes (full inward swing) | No (unless tilt-in sash) |
| Typical lifespan (years) | 20–25 | 25–30 | 30–50 (with maintenance) |
Sources for all numbers: Checkatrade cost guide 2026, GGF technical data 2026, and DESNZ Product Characteristics Database 2026 for U-values.
The direct answer tilt-and-turn windows win on energy efficiency and convenience, but casements are cheapest
For a UK homeowner comparing tilt turn vs casement vs sash, the tilt-and-turn offers the best energy performance with a U-value of 1.0–1.2 W/m²K and the easiest cleaning. However, it comes at a price premium of 30–70% over casements.
Casements are the most budget-friendly choice, starting from £400 installed, and are adequate for most homes. They cannot be cleaned from inside and have poorer sealing than tilt-and-turn windows. Sash windows are the most expensive and least efficient option. They are the only choice for period properties in conservation areas or listed buildings where style is a legal requirement.
Guide to U-values and window energy ratings
Eligibility and certification how to verify a window installer in the UK
All replacement window installations must comply with Building Regulations Part L (conservation of fuel and power) and Part F (ventilation). Installers must be registered with a Competent Person Scheme (CPS) to self-certify. The main schemes for windows are FENSA (Fenestration Self-Assessment Scheme) and CERTASS (GOV.UK guide on competent person schemes, 2026).
For sash windows in listed buildings or conservation areas, the installer must have experience with heritage joinery. The work may require Listed Building Consent from the local planning authority (Historic England guidance, 2026). For tilt-and-turn or casement windows, check that the installer is TrustMark-registered and that the window system is certified by the British Board of Agrément (BBA) or has a UKCA mark.
Always ask for a written quotation that includes the U-value of the glazing unit and the window system’s energy rating. An A+ or A++ rating is recommended for best performance.
How to check a FENSA-registered window installer
Frequently Asked Questions
Tilt-and-turn windows are the most energy efficient, achieving a U-value of 1.0-1.2 W/m²K according to industry data. Casements are next at 1.2-1.4 W/m²K, while sash windows are typically the least efficient.
Casement windows are the cheapest, costing £400-£700 installed for a standard size according to Checkatrade's 2026 cost guide. Tilt-and-turn windows cost 30-70% more than casements.
Tilt-and-turn windows offer better energy efficiency (U-value 1.0-1.2 vs 1.2-1.4) and easier cleaning according to the Glass and Glazing Federation. However they cost 30-70% more than casement windows.
Yes, sash windows are often the only option allowed for period properties in conservation areas according to local planning rules. They must typically match the original style and materials.
A standard 1200mm x 1200mm uPVC casement window costs £400-£700 installed according to Checkatrade's 2026 cost guide. Prices vary by size, glazing, and location.
