Warmer

Boost building performance, preserve character

Whether you're aiming to improve comfort, cut energy bills, improve EPC ratings or meet sustainability targets, secondary glazing is a smart retrofit solution. By introducing an insulating air gap and using low-emissivity (low-E) glass, our systems reflect radiant heat back into the room while thermally isolated frames and high-performance seals reduce draughts and airborne pollutants. We can’t advise on the exact U-Value you’ll need, but we can recommend the right product to meet your performance goals and project brief. And we’ll install it in a discreet, sympathetic way that respects the building’s original character.
Contact us

Helping you meet regulations and standards

Building Regulations Part Our products support compliance with Building Regulations Part L, which sets minimum energy efficiency standards for renovations and upgrades. BREEAM As the UK’s leading sustainability assessment method, BREEAM rewards energy-efficient upgrades.
Secondary glazing contributes to higher scores in categories like Energy, Health & Wellbeing, and Thermal Comfort. EPC & MEES Under the Minimum Energy Efficiency Standards (MEES), properties must achieve an EPC rating of E or above to be leased. Secondary glazing is a fast, practical way to improve EPC ratings – helping landlords meet legal requirements and attract tenants. EnerPHit Retrofitting to EnerPHit standards requires airtightness, insulation and thermal efficiency – all of which secondary glazing supports. It’s especially valuable in heritage buildings where external upgrades aren’t always possible.
 WELL Building Standard Thermal comfort is a key factor in WELL certification. Our systems help regulate indoor temperatures and reduce cold spots, contributing to healthier, more comfortable environments.

Thermal performance at a glance

Our products have been independently tested by the Centre for Window and Cladding Technology (CWCT) to assess U-Values across timber and metal primary windows.

	Timber primary + secondary unit 100mm cavity					Metal primary + secondary unit 100mm cavity
Product	6mm clear float	6mm low-E	4-12-4 SU low - E glass	4-12-4 SU low-E and gas	24mm Enhanced Thermal Sealed Unit	6mm clear float	6mm low-E	4-12-4 SU low - E glass	4-12-4 SU low-E and gas	24mm Enhanced Thermal Sealed Unit
S10 HS	2.629	1.807	-	-	-	2.911	1.936	-	-	-
S80 HS	2.640	1.810	-	-	-	2.920	1.940	-	-	-
S85 HS	2.700	1.840	-	-	-	3.000	1.970	-	-	-
S20 VS	2.617	1.802	-	-	-	2.897	1.930	-	-	-
S60 TVS	2.639	1.812	-	-	-	2.924	1.942	-	-	-
S90 VS	2.615	1.801	-	-	-	2.894	1.929	-	-	-
S95 VS	2.698	1.840	-	-	-	2.996	1.974	-	-	-
S41 SHC	2.581	1.785	1.676	1.627	1.27	2.852	1.910	1.786	1.731	1.34
S45 SHC	2.576	1.782	-	-	-	2.846	1.908	-	-	-
S50 SHC	2.589	1.788	1.758	1.700	1.32	2.862	1.915	1.879	1.813	1.38
S41 DSHC	2.588	1.788	1.865	1.832	-	2.861	1.914	2.003	1.964	-
S45 DSHC	2.585	1.786	-	-	-	2.857	1.912	-	-	-
S50 DSHC	2.598	1.793	1.966	1.927	-	2.874	1.920	2.120	2.074	-
S30 LO	2.585	1.787	-	-	-	2.858	1.913	-	-	-
S41 LO	2.581	1.785	1.676	1.627	1.27	2.852	1.910	1.786	1.731	1.34
S45 LO	2.576	1.782	-	-	-	2.846	1.908	-	-	-
S40 FL	2.574	1.781	1.517	1.435	-	2.843	1.906	1.606	1.515	-
S46 FL	2.579	1.784	-	-	-	2.850	1.910	-	-	-
S55 DFL	2.612	1.800	-	-	-	2.891	1.927	-	-	-

Glossary

U-Value A measure of heat transfer through a material. Lower U-values = better insulation. G-Value Indicates how much solar energy passes through glazing. Higher values can boost passive heating in winter. Low-E Glass Glass with a near-invisible metallic coating that reflects heat back into the room while letting in natural light.