Energy

At The Definitive Collection, we are committed to the continuous improvement of our products, offering one of the most comprehensive ranges of high-performance windows and doors in the fenestration industry.

Window Energy Ratings (WER) and Door Energy Ratings (DER) are measured on a scale from E to A++. These ratings assess overall performance, including how effectively products retain heat, reduce draughts, and maximise beneficial solar gain.

We offer a wide range of double-glazed and triple-glazed products that are fully licensed through the ERC / PLC scheme, achieving energy ratings of A, A+ and A++. Energy ratings do not solely measure the U-value (heat loss); they also take into account the G-value (solar gain) and L-value (air leakage), providing a true reflection of real-world performance.

The energy index is defined as follows:

• A-rated: 0–9

• A+ rated: 10–19

• A++ rated: 20–29

Glass specification plays a critical role and varies depending on the configuration of each double or triple glazed unit. Unlike many companies that use lower-cost alternatives, we specify low-iron glass on our energy-rated products. This significantly improves solar gain (G-value) and overall efficiency.

By choosing energy-rated windows and doors, you are investing in a warmer, more energy-efficient home with reduced environmental impact, lower heating bills, and long-term value.

Consumers can verify the authenticity of an energy rating label by checking the manufacturer’s licence number. As awareness of energy efficiency and environmental responsibility continues to grow, being part of a recognised scheme provides reassurance that our products meet the highest standards of performance and sustainability.

Please note: customers should always confirm with their installer which products are licensed and their specific performance ratings.