AT-ECO offers EnerPHit retrofit windows & doors for upgrading existing homes to Passive House standards. Achieve superior energy efficiency, comfort & air quality with Internorm, Reynaers, Schüco & Drutex.
Upgrade Without Compromise. Retrofitting doesn’t have to mean cutting corners. At AT-ECO, we help homeowners, housing developers, and architects bring older buildings up to future-ready energy standards using products that support EnerPHit certification — the Passive House standard for retrofits.
EnerPHit is the retrofit version of the Passive House standard, developed by the Passive House Institute. It provides a performance-based framework to dramatically improve energy efficiency in existing buildings while maintaining comfort and indoor air quality.
EnerPHit is ideal for:
EnerPHit certification can be achieved via:
| Metric | Requirement (Typical) |
|---|---|
| Space Heating Demand | ≤ 25 kWh/m²/year |
| Airtightness | ≤ 1.0 air changes/hour @50Pa |
| Component U-Values | ≤ 0.85 W/m²K (windows/doors) |
We offer premium products designed for high-efficiency upgrades with minimal structural changes.
| Product | U-Value (W/m²K) | Frame Material | Glazing | Retrofit Suitability |
|---|---|---|---|---|
| Internorm HF510 | ~0.65 | Timber-Aluminium | Triple | Excellent thermal & acoustic |
| Internorm KF410 | ~0.62 | uPVC-Aluminium | Triple | Slim profile, I-tec glazing |
| Drutex IGLO ENERGY | ~0.71 | uPVC | Triple | High efficiency, flexible fit |
| Schüco AWS 90.SI+ | ~0.77 | Aluminium | Triple | Certified Passive-ready |
From Victorian townhouses to rural farm conversions, we help bring dated properties into a zero-carbon future.
We cover London and the South & East of England, including:
Working closely with architects, builders, and homeowners, we’ve delivered systems that combine thermal efficiency, modern aesthetics, and long-term durability—across private residences, sustainable developments, and architect-led designs.
The renovation project was successfully completed on schedule, surpassing initial insulation and energy efficiency goals by an impressive 70% and delivering a sleek, contemporary finish.
View the project
Explore Harriet's Lodge, a House of the Year nominated new build in Southampton, featuring AT-ECO timber-aluminium windows, Passive House standards, and smart home integration.
View the project
Explore Charlie Luxton's stunning Passive House new build in Beanacre, Oxfordshire, achieving an A++ energy rating with AT-ECO timber-aluminium windows, MVHR, and smart home tech.
View the project
Explore Stockhouse Farm, award-winning A++ Passive House terraced homes in Surrey designed for modern families, blending traditional design with cutting-edge energy efficiency.
View the project
Explore The Cook's House: a contemporary detached house in Gloucestershire blending classic architecture with sustainable design and AT-ECO timber-aluminium windows.
View the project
Explore Blackwood, an award-winning Passive House in urban Bedfordshire ('Best Self Build' 2023) featuring AT-ECO triple glazing, solar blinds, and airtight construction for max energy efficiency.
View the project
Explore this stunning coastal new build in Bexhill on Sea, East Sussex, featuring AT-ECO high-performance triple glazing and marine-grade finishes for resilience & maximised views.
View the project
See the Squirrels Chase project: a home transformation in Bromley enhancing thermal performance, comfort, & curb appeal by replacing windows & doors with AT-ECO Internorm systems.
View the project
Explore Hunters Hill, an exceptional Passive House in Guildford showcasing sustainable living with AT-ECO high-performance windows, solar panels, Tesla batteries, and Loxone smart home tech.
View the project
Explore Lower Priory Farm: a luxurious new build in Stanmore, London, blending contemporary design with sustainability and featuring expansive glass & AT-ECO timber-aluminium windows.
View the project
Explore Chalkwood: a modern coastal Passive House in St Margaret's at Cliffe, Dover, featuring AT-ECO windows/doors, marine-grade finishes, and stunning sea views for sustainable living.
View the project
Explore Tanglewood: a unique Passive House in St Margaret's at Cliffe, Dover, recessed into the landscape, blending design with nature & AT-ECO high-performance windows for a sustainable retreat.
View the project
Explore Blenheim Terrace: a collection of three luxury townhouses in London's St John's Wood conservation area, blending modern design with traditional charm & AT-ECO high-performance windows.
View the project
Explore the Notting Hill Gate South Block refurbishment in London, blending modern Schüco curtain walling with 1950s architecture for enhanced energy efficiency & style.
View the project
Explore Slips House: an innovative Paragraph 80 home in Hertfordshire's AONB, integrated into the landscape with a grass arch & Reynaers systems for outstanding sustainability.
View the project
Explore 'Forty': a sustainable London family home featured on Grand Designs, showcasing AT-ECO high-performance triple glazing & Passive House principles for urban living.
View the project
Explore Black Barn Studios: an award-winning sustainable workspace in Oxfordshire, a repurposed barn achieving Passivhaus principles with AT-ECO high-performance windows & exceptional airtightness.
View the project
Explore Market Place: a luxury apartment development in Henley-on-Thames, combining rustic charm with contemporary living & AT-ECO high-performance windows/doors.
View the project
Explore Skyridge: an award-winning sustainable contemporary home in Surrey Hills with an A-96 energy rating, featuring AT-ECO high-performance glazing & smart systems.
View the project
See the Petersfield renovation in East Hampshire, enhancing comfort & style with AT-ECO Internorm windows & doors, including integrated blinds, for improved energy efficiency.
View the project
Explore Lamorna: a sensitive 1960s Cotswold renovation blending contemporary design with conservation needs, featuring AT-ECO high-performance glazing & curtain walling for a low-energy home.
View the project
Explore the transformation of Market Road: a former London printworks into a sustainable 45,000 sq ft office HQ, blending modern design with industrial heritage using AT-ECO Reynaers systems.
View the projectStay informed with detailed material comparisons, installation tips, and practical maintenance strategies designed to maximise the longevity and performance of your windows and doors.
Creating your dream home? Visit the Homebuilding & Renovating Show! Expert advice, top brands & real inspiration—all in one place. We’re exhibiting, come say hi! 👋
Yes, we recommend booking an appointment to ensure personalised service and availability. You can schedule your visit by filling out our contact form or emailing us at [email protected].
During your visit, our team will guide you through our range of premium window and door systems. We’ll answer your questions, help you explore customisation options, and assist in finding the perfect solution for your project.
Absolutely! Bringing your project plans or drawings can help our team better understand your needs and provide tailored recommendations.
Our knowledgeable team is here to help. Whether you need advice on materials, styles, or energy efficiency, we’ll guide you through the process and ensure you make an informed decision.
Book your free home survey today and discover the perfect fit for your property.
