Best Double Glazing Providers for Passive House Standards

Passive Home isn't a badge you stick on at the end. It begins with the frame sightlines, the spacer bar, the tolerances on the gasket, and the method the sash meets the weatherseal in February sleet. I have actually fitted windows in Camden terraces with wonky brickwork, comprehensive drape walling for a school in Lewisham, and commissioned triple‑gasket alu-clad frames for a mews in Kensington. If you want the thermal efficiency and airtightness that Passive Home demands, you require providers who comprehend more than U-values on a brochure. You require a team that will get the phone when your PHPP tosses a curveball and your psi values don't associate the lintel. This guide sets out how I examine double glazing providers for Passive House‑level efficiency in London, which brands in fact provide, and where the typical risks lie for designers and homeowners.

What "Passive House‑level" suggests for glazing in London

Passive Home Institute sets a window target Uw of 0.80 W/m ² K or better, referenced to the installed state, with warm edge spacers and really low psi values around the boundary. Most London jobs are repairs or blended fabric develops, so we often work to a pragmatic short: achieve Uw 0.80 to 1.0, g-values between 0.45 and 0.60 depending upon solar gain strategy, airtightness Class 4 to EN 12207, and a well-documented setup information that keeps the frame in the insulation line. You can reach this with high-spec double glazing just in uncommon cases, for example small-format openings with aerogel exposes and exceptional spacers. For a lot of elevations, particularly on busy roads in Islington or Hammersmith, a well balanced triple glazing bundle is more realistic. That stated, the market has actually moved, and a couple of double glazed systems with innovative finishes and krypton fills can attain excellent numbers on modest apertures. The challenge is getting robust, repeatable performance on website, not simply a lab certificate.

The UK's regulatory structure matters too. Part L tightens energy efficiency; Part O now brings overheating to the fore, particularly in south and west-facing flats in Southwark or Wandsworth. Glass requirements isn't just about U-value: you require to handle solar control, daytime element, acoustic attenuation for traffic on the A10 or the Overground, and useful security to PAS 24. Meanwhile, accreditation is your peace of mind check. FENSA licensed window installers or CERTASS approved firms assure compliance for domestic replacements. For energy scores, I still look to BFRC ranked glazing providers when I desire quick apples-to-apples contrasts of whole-window efficiency, though for Passive House, PHI component accreditation and in-depth information sheets beat basic A+ sticker labels every time.

The truth on double versus triple for Passive Home targets

I'm in advance with clients: to consistently strike Passive Home targets on standard-sized doors and windows, triple glazing with warm-edge spacers and insulated frames is the standard. Where double glazing still holds its own is in constrained heritage contexts or when budget requires a compromise. In a sanctuary in Hackney, we accomplished a job target by using high-spec double glazed sash replacements with low‑E finishes, argon fill, and thoroughly detailed draughtproofing, then compensating elsewhere with enhanced wall insulation and MVHR optimisation. But the windows themselves only simply cleared a Uw of around 1.1 to 1.2 W/m ² K set up, not Passive House class.

If a provider declares their double glazed sash does Passive House, checked out the spec: are they pricing estimate centre‑pane Ug of 1.0 with argon gas double glazing, or whole-window Uw with support and hardware accounted for? Ask for the BFRC rating for reference, however demand the element breakdown used in PHPP. Examine the spacer bar (a real warm-edge, not simply coloured), the secondary seals, and the psi-install value they presume. In London refurbishments with brick exposes, the perimeter loss can reverse the benefits of an excellent glass package if the frame sits cold and happy with the insulation line.

Materials: uPVC, timber, aluminium, and alu‑clad at Passive Home level

uPVC doors and windows can reach extremely low U-values when profiles have multi‑chamber building and construction and decent steel-free support. For cost-effective Passive House attempts, uPVC stays compelling. That said, standard uPVC windows London homeowners are used on the high street often fall short, with average double glazing and fundamental steel supports that bridge the chambers. For Passive Home, search for profiles with foam-filled chambers and proprietary thermal inserts. If you're set on double glazing, a uPVC frame optimised for triple makes double efficiency more stable, however you still require to scrutinise gaskets and seals.

Timber and alu‑clad (timber inside, aluminium exterior) provide exceptional thermal performance with clean sightlines, and I define them regularly for architect-led jobs in Camden, Haringey, and Richmond. Effectively crafted laminated timber frames with triple gaskets can dependably achieve Uw listed below 0.8 when paired with ideal IGUs. For longevity in London's weather and contamination, aluminium cladding lowers upkeep. You do require a provider who deals with moisture management and factory completing properly. Wood that is simply "treated" however badly sealed at end grain will swell and compromise airtightness by year three.

Thermally broken aluminium windows are a various story. Aluminium doors and windows appeal for slim profiles and structural capacity, especially for sliding doors London projects or aluminium bifold doors London homeowners love throughout cooking area extensions. For Passive Home efficiency, the break must be significant and continuous, and the glazing platform created for triple. Best-in-class aluminium systems utilize high-density polyamide thermal breaks with foam infills, undercut isotherms, and multi‑chamber sashes. I only trust a handful of aluminium windows London suppliers for Passive Home tasks, and we check mock-ups for condensation risk. With double glazing, thermally damaged aluminium windows can look gorgeous however seldom hit Passive House numbers on anything but small panes.

Shortlist of trusted double glazing providers London teams use for Passive House‑level work

I won't list every window and door company in the capital, and I will not pretend all of these routinely provide Passive Home with double glazing alone. These are manufacturers and windows and doors providers London architects and contractors call when they require documentation, efficiency, and set up assistance to match high requirements. Accessibility and lead times change, however the principles for picking among them remain.

• Green Structure Shop (by Effective Structure Solutions): Their Efficiency and Ultra ranges are known in the Passive Home neighborhood. The Ultra variety is triple-first, however Performance uses strong double choices for smaller sized openings. They bring reliable psi information, warm-edge spacers, and support with PHPP entries. I have actually used their timber-alternative uPVC lines for budget-friendly double glazing London repairs, accomplishing airtight installs with taped frames.

• Internorm: Austrian huge with PHI-certified elements. Many Internorm plans I define are triple, but some double alternatives exist for secondary spaces. Impressive documents and systemised installation accessories. For east-facing elevations in Barking where expense pushed back, we mixed double for utility rooms with triple on primary living locations, keeping the brand name consistent for seals and hardware.

• Velfac and Rationel: Danish alu‑clad timber professionals. Their triple is the sweet area for Passive House; double glazing remains appealing on carefully designed elevations to handle g-values. They're strong on QA, finishing, and acoustic information. For Walthamstow balconies, we often combine their units with insulated install frames and airtight tapes to nail blower tests.

• Reynaers and Schüco by means of specialist producers: For aluminium doors and large sliders, these systems supply robust thermally damaged aluminium windows and moving doors with superior rolling gear and gasket stability. PHI-certified frames exist, though double glazing versions are typically not Passive House. Still, for sliding doors London customers want to open to the garden, you can model solar control glass, low-e finishings, and bigger thermal breaks to keep overall performance balanced.

• Bereco and Westcoast Windows: Wood and alu‑clad wood providers with strong UK presence, ideal for bespoke units, French doors London projects, and contemporary window designs. They back up efficiency claims with BFRC data and great service when you need a customized mullion or a non-standard limit information that still maintains airtightness.

I likewise deal with custom-made window makers London based who put together frames around high-spec double glazed systems from Saint‑Gobain, Pilkington, or Guardian, using Swisspacer or Thermix warm-edge bars. If you go this route, insist on complete IGU certification, gas fill confirmation, and toughened/laminated setups to satisfy security and acoustic needs. On business glazing providers London side, a fabricator confident in CWCT screening and EN standards can deliver robust shops and drape wall transitions that dovetail with domestic double glazing London packages.

Glass spec: not simply Ug

For Passive House ambitions, begin with low e glass windows utilizing a soft‑coat low‑E like SGG Planitherm or Pilkington Optitherm, and define argon as basic with a warm edge spacer. Krypton only makes good sense in narrow cavities where sightlines should be maintained; it becomes cost‑ineffective in standard 16 mm cavities. Argon gas double glazing at 4/16/4 with a centre pane Ug of 1.1 W/m TWO K is common, however the magic is in the spacer, secondary seal, and pane develop. Toughened panes decrease nickel sulphide risk on door sets, and laminated panes enhance security and acoustic attenuation.

For solar control in west-facing extensions in Brent or Ealing, consider a selective coating that brings the g-value down to 0.35 to 0.45 without eliminating daytime. Be wary of stacking too many layers of coating on double glazing; colour shift and external reflectance can annoy planners in conservation zones. Acoustic interlayers matter along the Overground in Shoreditch; uneven glass develop like 6.8 laminate/ 16/ 4 with low‑E can bring Rw to the mid‑40s dB, making interiors much more comfortable.

Installation is efficiency: the London information that decides blower tests

People fixate on frame and glass, then forget the install. Passive House‑level windows and doors require a repeatable installation approach. On period brickwork in Hammersmith with rolling reveals, we frequently set the frame back into the insulation plane using plywood or composite install frames, then seal internally with vapour‑tight tapes and externally with vapour‑open but leak-proof membranes. Expanding foam is not your air seal. It is a filler. The airtight line is the tape or gasket, continued to the wall air barrier. Sills require end dams, not silicone prayers.

I choose to pre‑drill repairing points outside zones of greatest thermal gradient. Use thermally broken dealings with if you can, or at least minimize metal penetrations. On aluminium doors, beware with thresholds. A lot of patio doors London jobs fail since the limit bridges insulation or leaves a wicking course for rain. A slimline appearance is excellent, a cold bridge is not. Coordinate with the flooring accumulation, insulation, and DPM early, or you'll be chiseling by week 6.

Certification, scores, and why they matter

• FENSA licensed window installers or CERTASS approved double glazing companies assist with structure control sign-off and customer security. For replacement windows in domestic tasks throughout Tower Hamlets or Croydon, self‑certification conserves time, but you still require to confirm that the actual installed product meets specification.

• BFRC ranked glazing suppliers offer a streamlined label, helpful for mainstream energy effective windows London buyers. For Passive Home, push beyond A++ labels and demand comprehensive declarations: Uf, Ug, g, psi values, airtightness and watertightness classes, and if available, PHI component certificates.

• PAS 24 and Secured by Design matter for front doors and back entrances London property owners require for insurance coverage. Many high‑performance frames can be defined with laminated panes and enhanced lock keeps without blowing the thermal budget.

• For commercial, check EN 14351‑1 markings, wind load data, and CWCT testing for drape wall or large glazed frames in mixed‑use jobs. A residential double glazing London supplier may struggle when a shopfront needs tested mullions and deflection control.

uPVC versus aluminium for Passive House‑minded projects

uPVC windows London providers offer aggressive rates and brief preparations, which can keep a retrofit on budget plan. With the right profile, double glazing can reach decent efficiency for energy rooms, bed rooms on sheltered elevations, and secondary spaces. For primary living locations, especially with bigger panes, triple wins. uPVC doors can feel chunky; limit spans or expect flex.

Aluminium doors London clients ask for the kitchen-to-garden link bring elegance and slimmer sightlines. To protect performance, define thermally broken base profiles, lift‑and‑slide gear, and trickle vents that do not torpedo airtightness. I like to combine large aluminium sliders with repaired panes in high‑performance frames on the flanks, keeping the moving door count low. For bifold doors London homes, be realistic about air leak. Even premium sets have more joints; if you require Passive Home airtightness, a lift‑slide is a much safer bet.

Managing heritage and preparation in London boroughs

In Westminster, Camden, and parts of Kensington and Chelsea, conservation officers appreciate sightlines, putty lines, and reflections. Slimline double glazed systems can pass where triples will not fit. You'll be picking heritage putty lines, warm-edge spacers in neutral tones, and possibly vacuum glass for Grade II noted properties if the budget plan permits. In these cases, the rest of the envelope must work harder. We have actually delivered comfy and effective homes with u-values that do not rather hit Passive Home by counselling clients into mechanical ventilation with heat recovery and careful draught proofing. Passive convenience is a system, not a single window.

Price truth and procurement in the capital

For economical double glazing London house owners can rely on, anticipate practical figures. A quality uPVC sash with argon, low‑E, warm-edge spacer, and correct installation sits approximately at ₤ 450 to ₤ 700 per opening for little units, increasing with size and hardware. Wood alu‑clad windows that get you close to Passive House typically vary ₤ 900 to ₤ 1,400 per opening for modest sizes. Big moving doors can run ₤ 3,000 to ₤ 10,000 depending upon span, system, and glass. If a quote feels too excellent, it probably swaps warm-edge for aluminium spacers or downgrades seals. On Passive Home tasks, aspect setup membranes, tapes, housewrap shifts, and commissioning time. Those information cost cash however provide efficiency that sticks through winter.

How I examine a supplier for Passive Home projects

I run a short diagnostic early. It saves weeks downstream and weeds out glossy brochures.

• Can they provide whole‑window Uw, Uf, Ug, g, psi‑edge, and psi‑install numbers backed by test reports or PHI data, not simply marketing?
• Do they use warm‑edge spacers as standard, with confirmed gas fill and double seals on the IGU?
• Will they support an airtight installation information with tapes and devices, and can they show me an area through the sill that handles water?
• Are they comfy talking about Part O and overheating technique, not simply winter performance?
• Do they have FENSA or CERTASS pathways for replacement work, and can they meet PAS 24 where needed without unsightly add‑ons?

A supplier that responds to these crisply is currently in the leading quartile. The very best double glazing suppliers likewise admit where double won't hit your target and assist you change to triple strategically.

Real world mixes that work in London homes

A three-storey semi in Haringey: we used alu‑clad wood triple for the street elevation to deal with acoustics and cold wind, with centre panes at Ug 0.6, g around 0.5 for daytime. Garden elevation received a big aluminium lift‑slide door with high-spec double glazing, g-value tuned to 0.37 to fight afternoon summer gain. By placing the slider in the insulation line, taping the border, and including insulated limits, we kept heat loss in check. The PHPP model allowed this blend to hit convenience without overheating, and the blower test can be found in at 0.4 ACH, thanks in part to airtight reveals.

A ground-floor flat retrofit in Lambeth with budget plan pressure: uPVC windows and doors across the board, double glazing with low‑E and argon, Swisspacer Ultimate warm edges, and laminated panes to relax road noise. We taped internally, utilized compriband externally, and wrapped sills. The Uw settled around 1.1 to 1.2 installed. Not Passive Home, but a step modification in convenience at a sensible cost. We pushed MVHR and insulated the suspended floor to make the entire system feel consistent.

A loft conversion in Wandsworth: rooflights with high-performance triple to tame summertime gain, but double glazed sashes on the dormer to keep weight down and maintain slimmer transoms. The provider offered psi‑install numbers and pre‑applied membranes. We used vapour‑closed tapes within, vapour‑open outside, and resolved the thermal bridge at the steel. Even small openings need complete documents if you desire efficiency when the wind is up.

Doors: thresholds, security, and thermal reality

Front doors and back doors London homes depend on must not be the thermal powerlessness. Composite doors can strike exceptional U-values, but air leak at the limit is the hidden enemy. Always request laboratory air permeability class and a cutaway of the limit, not simply an image. For French doors London clients like, define a continuous gasket at the meeting stile and an adjustable keep that holds tight year-round. If you're choosing aluminium doors London style, a rebated threshold with thermal break and correct drainage performs much better than a flush threshold that counts on silicone. Balance ease of access with toughness and thermal requirements by recessing thresholds into insulation and collaborating floor finishes early.

Sustainability and lifecycle

Sustainable glazing London conversations ought to include embodied carbon. Wood and alu‑clad wood generally outshine aluminium on embodied energy, though recycled content aluminium and long service life complicate that story. uPVC has enhanced solutions and recycling streams, but request paperwork. Durability is the greenest function: long lasting surfaces, replaceable gaskets, and IGUs from a double glazed units manufacturer London or UK based with stable supply lines decrease future waste. I like suppliers that can change blown units without tearing apart trims or harmful airtight tapes.

When double glazing suffices for a Passive House‑inspired project

There are cases, particularly with small, well-shaded openings, where double glazing from relied on glazing specialists London based can satisfy requirements. Think energy spaces, north-facing restrooms, or stairwell windows where the pane is modest and the frame is super-insulated. Use the very best double glazing suppliers you can discover to secure low‑E coverings, argon fill, warm‑edge spacers, and a robust frame. Keep g-values reasonable for daytime. Most importantly, model it honestly in PHPP or at least a reliable thermal tool, and make certain the perimeter detail does not undermine you.

Practical procurement tips for property owners and architects

• Demand full technical packs early: area illustrations, Uf, Ug, psi values, gasket details, and installation handbooks with tapes and membranes listed.
• Mock up a vital opening on website before committing the entire order, specifically for aluminium sliders and bifolds with tight tolerances.
• Cross check quotes for like‑for‑like glass: low‑E type, gas fill, spacer spec, and laminated panes for security. Numerous "low-cost" quotes conceal aluminium spacers or weaker seals.
• Coordinate sill and expose insulation before buying. A 20 mm change in plaster build can shift your frame position out of the insulation line.
• Use FENSA licensed window installers or CERTASS authorized double glazing teams for domestic work, and hold a pre‑start meeting to walk through airtightness sequencing.

Final thoughts from the site and the spreadsheet

The best double glazing providers are not specified by the shiniest display room in Shoreditch or the boldest A++ sticker. They are the ones who help you fix edge cases: the celebration wall reveal that pinches, the slender mullion that runs the risk of condensation, the veranda door whose limit requires to keep water out without freezing your toes in January. In London, with its patchwork of terraces, mansion blocks, and contemporary infills, no single brand name matches all. I change between uPVC doors and windows for budget-critical retrofits, alu‑clad lumber for high-performance Passive House builds, and thermally damaged aluminium windows for periods and very little sightlines. On doors, I guide clients towards lift‑slide systems over bifolds when airtightness matters, and I temper the love of floor‑to‑ceiling glass with a sober look at Part O and summer season comfort.

If you take one thing from this, let it be that efficiency is a chain. A BFRC rated glazing provider, PHI‑calibre frames, low‑E finishes, argon fills, warm-edge spacers, and careful installation tapes are all links. Miss one, and you'll see it on your energy expenses and feel it at the back of your neck on a cold, windy night. Choose suppliers who talk in numbers and information, not just adjectives. Your Passive Home aspirations will thank you in February, when London's wet wind is doing its best to discover a weak point, and your windows just shrug it off.

Doorwins Windows and Doors stand as one of the leading aluminium glazing companies in London. We design, fabricate and install modern double glazed units for modern homes and luxury developments.

Each project delivered by Doorwins reflects years of expertise and precision engineering. Need help choosing secure composite front doors, Doorwins will provide a tailored, supply-and-fit solution.

Being one of London’s number one windows and doors specialists, we maintain our reputation by delivering transparent service, competitive pricing and guaranteed aftercare.

Doorwins aluminium windows and doors
Address: Office 3, 186 Greenford Ave, London W7 3QT
Phone: 020 8629 1171

Products and Services Offered by Doorwins

Doorwins manufactures and supplies a wide range of premium glazing products and architectural aluminium systems across London and the UK. Our expert team handles every stage of the process — from design and fabrication to supply-only and full supply-and-fit installations.

• Aluminium Windows (Casement, Tilt & Turn, Slimline, Heritage Styles)
• Aluminium Doors (Front, French, Patio & Sliding)
• Bifold Doors – Contemporary Slim Profile Systems
• Roof Lanterns & Skylights
• uPVC Windows & Doors
• Double & Triple Glazed Units
• Commercial Shopfronts & Curtain Walling
• Energy-Efficient Glazing Solutions
• Hardware & Accessories (Handles, Locks, Thresholds)

Our services include:

• Manufacture Only – Tailor-made units built to your specification.
• Supply Only – Delivered ready for installation by your own team.
• Supply & Fit – Fully managed service from survey to installation and aftercare.

With decades of expertise and an unshakable reputation for quality, Doorwins remains a trusted name in aluminium and double glazing across Greater London.