Which are the most energy efficient windows?

When you’re considering glazing options for your new home, self-build, renovation or window replacement, good energy efficiency is often top of the list of requirements.

Energy efficient glazing helps to reduce energy bills and your carbon footprint – whether it’s double glazing, triple glazing, secondary glazing, or even draught excluders or thicker curtains.

The efficiency of a window can be measured in U-value – a measure of how easily heat can pass through a material. Materials that let out more heat have a higher U-value and materials that let less heat pass through them have lower U-values.

For example, single glazing might typically have a value of 5.0 W/m2k, whereby modern double-glazing can achieve 1.6 W/m2k, with Westcoast Windows triple-glazed Design Series achieving U-values as low as 0.9 W/m2k.

Energy efficient glazing has other benefits too. It can help you achieve a more comfortable home, meaning fewer draughts and cold spots in the winter, it can also help to reduce external noise and it can help to reduce condensation build up on the inside of windows.


Energy efficient windows are available in a range of frame materials, including uPVC, wood, aluminium or composite frames…

Timber windows, when combined with sealed units provide a traditional look with good insulating properties and is arguably more naturally efficient than metal or uPVC. However they do require regular maintenance to keep them looking good.

uPVC windows have improved lately to achieve excellent energy efficient ratings, however may not be to everyone’s taste due to their thicker frames, potential discoloration and limited size options in manufacturing.

Metal or aluminium windows offer a durable, sleek, minimalistic style, although often they are not as energy efficient as other materials due to heat loss through metal frame. There have however been developments in thermal breaks to increase their energy efficiency, so check with the manufacturer.

Composite windows (often referred to as ‘aluminium wood windows’ or  ‘aluminium clad windows’) offer the best of both worlds – excellent energy efficiency combined with aesthetic appeal. True composite windows have a unique bonded construction consisting of an outer part of stylish aluminium, with an environmentally friendly powder-coated colour to suit your style, and an inner part of wood in pine, oak or other species, with a water-based natural clear lacquer or stained or painted to suit your interior. Westcoast Windows use PEFC certified wood, which guarantees that it comes from renewable sources.

Due to their aluminium and timber construction, Westcoast composite windows are fully recyclable.


Additionally Westcoast Windows has sustainability at its heart – our manufacturing facilities are based at Trollhättan on the West coast of Sweden where residents and commercial businesses benefit from years of investment into sustainable energy technology. The local heating system recovers excess energy from industrial activities which is recycled and complemented with local biomass production to heat the whole city. Westcoast Windows’ waste timber contributes to this renewable energy source and power generation is principally from Trollhättan’s own hydro-electricity plant, supplemented by local wind farm and solar energy sources with occasional nuclear support at times of exceptional demand.

Read our environmental policy here: WESTCOAST ENVIRONMENTAL


Which are the most energy efficient windows?
Which are the most energy efficient windows?
Which are the most energy efficient windows?
Which are the most energy efficient windows?