Green Building Store is now 21°


We believe you thrive in the places where you experience comfort. Discover our range of high performance triple-glazed windows, suitable for low energy and Passivhaus homes.

Our windows

Making home a more comfortable place to be

We improve the very fabric of your building, making it energy efficient and a healthier and more comfortable place to be. Windows that are triple glazed have three panes of glass instead of the more common single or double glazed windows. The extra argon filled cavity in a triple-glazed window offers an extra layer of insulation, making them more energy-efficient.

We've introduced a slimmer frame whilst maintaining dual compression seals for achieving high air tightness standards. Make a genuine difference to the comfort of your home by keeping your home warm during the colder months and cooler during the summer.

So, trust in our 30 years of experience helping people create energy efficient dream homes. Let us be part of your team, and we'll be with you every step of the way, delivering comfort by making buildings better.

Our window range

Our window ranges are available in two types of frame and two depth options; timber and aluminium clad timber. *78 or 98 refers to the depth of the window frame. All our windows are responsibly source using FSC® certified timber.

Certified and quality tested

All of our products are thoroughly tested and quality assured.

FSC Certified Wood

Part Q Compliant

Secured by design

Make your windows unique to you


Customise your new windows with your preferred hardware.

Frame styles

There's a range of frame options for your windows. Please speak with a member of our team for other options.

Glazing options

We offer a range of glazing options to give you the flexibility you need.

How do triple-glazed windows work?

Each layer of glass is separated by sealed gaps of Argon. These gaps act as insulation that keeps your home warm in the winter and cool in the summer.

Low U values

Argon-filled triple glazing as standard for comfort and great thermal performance


Dual compression seals ensuring long-term class 4 airtightness

High security

Multipoint locking tested to Secure by Design standard

We've worked hard to build a reputation for customer service, integrity and responsibility. We are committed to ensuring that our products are of the highest quality, backed by industry accreditations, and specified by companies at the forefront of energy-efficiency construction.

Luke Gilman - 21° Windows Department Manager


  • Please contact us for advice on the best range for your project.

  • Yes, we do! Our fitting service operates throughout the UK.

  • We provide up to 10 years warranty on our range of timber windows and doors. Speak to the team to find out more.

  • 21°s windows and doors are available in the RAL classic range and we also have a selection of natural wood stains to choose from.

  • In addition to our triple glazed timber windows and doors, 21° offers a wide range of products and services,  including advanced MVHR heat recovery ventilation, specialist airtightness & insulation products, and consultancy.

How can we help?

Visit the showrooms

Windows are a big investment, so come and visit our showrooms in Huddersfield and Swindon or catch us at exhibitions around the UK to see our products for yourself.

Request a quote

Tell us about your project, and we'll make sure you get a no-obligation quote from us. Take a step towards a more energy-efficient home today.

Get in touch

We offer a friendly and responsive aftersales service for our windows and door ranges, with a dedicated office and on-the-road aftercare team.

Life changing homes