The Independent’s journalism is supported by our readers. When you purchase through links on our site, we may earn commission. Why trust us?

How we cover windows: Our methodology explained

Our team of experts meticulously examines and reviews windows to ensure you can make a well-informed choice and enhance your home’s comfort and energy efficiency. 

To guarantee our window assessments are as exhaustive as possible, we thoroughly examine and evaluate 34 distinct criteria. Each window’s cumulative performance across these parameters forms its final rating, influencing our ultimate recommendation.

Each criterion is categorised into one of the following sections:

  • Performance and features
  • Supplier’s/manufacturer’s reputation and credibility
  • Customer experience
  • Environmental impact
  • Price

We weigh each feature’s importance based on its ability to define the best windows.

Window review stats

data points measured
categories considered
windows reviewed to date
hours testing and analysing windows
customer reviews read

The window features we prioritise

We think the critical factors in determining a window’s quality are:

  • Energy efficiency and performance
  • Features and security considerations
  • Durability and build quality
  • Available styles, designs and materials
  • Installation process
  • Manufacturer’s reputation
  • Price
  • Guarantees
  • Customer reviews

Energy efficiency and performance

In evaluating the energy efficiency of windows, several factors come into play. These include the window’s design, the type and amount of glazing, the materials used, and energy-efficient coatings or gases between panes (in the case of double-glazed and triple-glazed windows). Ratings such as the U-value, which measures the heat transference of glass, provide a clear measure of a window’s energy efficiency.

The overall performance of a window involves factors such as durability, sound insulation, and ease of operation. High-performing windows are durable and can withstand varying weather conditions without warping, cracking, or fading, while good sound insulation can significantly increase the comfort of your home, particularly in noisy environments.

Features and security considerations

The features of a window, such as a wide opening for easy cleaning, can significantly impact its overall utility and appeal. Security is also a key concern for homeowners. Windows are often a potential intruder’s entry point, so robust security features are crucial. This includes strong, durable frames, glass that resists forced entry, and reliable locking mechanisms. Some windows offer additional security features, such as laminated or tempered glass, which is harder to break, or lock sensors that can integrate with a home’s existing security system to alert homeowners if a window is left open or is tampered with.

Our experts examine every feature of each window, evaluating how impactful they are, while also stringently testing any incorporated safety measures to establish their robustness.

Durability and build quality

New windows are long-term investments, and – being exposed to various weather conditions – must be durable. Strong, hard-wearing windows maintain their functionality and appearance over time, resisting issues such as warping or fading. 

The build quality of a window is closely related to its durability. The frames should be solid and well-joined, the glass should be well-sealed to the frame, and moving parts, such as hinges, sliders, and locks, should operate smoothly.

Available styles, designs and materials

Windows contribute not only to the exterior appearance but also to the interior design of a home. Therefore, having a range of styles and designs allows homeowners to find options that best suit their home’s architectural style and personal taste.

The frame material influences its performance, maintenance needs, lifespan, and energy efficiency. For example, uPVC windows are typically more energy efficient and require less maintenance than wooden windows, but some homeowners may prefer real wood’s traditional look and feel.

Installation process

The installation process is a significant factor when assessing new windows. A properly installed window is crucial to ensure its optimal functioning, durability, and energy efficiency. If a window is incorrectly installed, even the best-quality product can underperform, leading to issues such as drafts, leaks, and a shortened lifespan.

Manufacturer’s reputation

The reputation of the manufacturer is highly significant when evaluating new windows. A reputable manufacturer generally indicates reliability, quality products, and good customer service.

Regarding customer service, reputable manufacturers will likely have established service networks and a track record of addressing customer concerns or issues efficiently and effectively.


It’s important to consider not just the upfront cost of windows, but also the long-term value of the investment, and our experts fully consider this aspect.

The initial purchase price includes the cost of the windows themselves, as well as any installation charges. However, it’s important to remember there may be more cost-effective choices than opting for the cheapest windows. Lower-cost windows may not perform as well in terms of energy efficiency, durability, or aesthetics, leading to higher costs over time due to increased energy bills, maintenance needs, or a shortened lifespan that necessitates replacement sooner than expected. Our experts also review whether you can save extra money via double glazed windows grants, depending on eligibility.


Windows represent a significant investment for homeowners, both financially and in terms of property value. The presence of a guarantee offers a level of financial security. It means the manufacturer or installer believes in the product enough to back it with a promise to repair or replace windows should they fail to perform as advertised within a specified period.

However, it’s not just about having a guarantee; it’s also essential to understand its terms and conditions. Some warranties do not transfer if you sell the property; others may not cover all parts of the window equally. Therefore, it’s critical to understand the guarantee’s small print. Our researchers are experienced in studying and analysing warranties.

Customer reviews

Customer reviews play a significant role when evaluating windows, offering a user perspective that manufacturers or sellers don’t provide. 

Reviews often highlight the quality and performance of the windows over time. Manufacturers can claim their products are durable, but reviews can affirm or challenge this assertion based on real-world experiences. This includes how well the windows insulate, their noise-cancellation effectiveness, and their resistance to weather conditions.

Our experts read hundreds of customer reviews to establish whether a window deserves our recommendation. 

You can read more about our commitment to editorial impartiality and our editorial code on our About Us page.

Katharine Allison

Energy Saving Writer

As Independent Advisor’s energy saving expert, Katharine, a keen advocate for sustainability, is an authority on solar panels, double glazing, and cutting-edge renewable energy technologies. Her dedication merges with a commitment to enlighten and steer readers toward embracing eco-friendly solutions and the latest trends in sustainability.

With over 10 years of experience, she has worked with some of the UK’s leading companies and publications, including the Federation of Master Builders, Architectural Digest, and Denon Construction. 

Katharine is particularly passionate about consumer causes and animal welfare and has art, philosophy, and psychology degrees. She lives with her sled dogs in East Sussex.