Passive House Windows Wooden and Aluclad Inward Opening DK88 Uw = 0.74 W/m2K

Click Preferred Method Below to Contact Us – We Offer Free Estimates & Expert Advice.


DK88 Inward Opening Window Triple Glazed Timber or Aluclad Passive House Window.

Uw = 0.74 W/m2K

The DK88 Inward Opening Window from Direct Line Timber Combines the Flexibility of an Inward Opening Tilt and Turn Window with Exceptional Energy Efficiency, making it Truly Hard to Beat. Certified as a Passive House Compliant Component by The Passive House Institute in Germany. Our DK88 Window is an Excellent Solution for Buildings Where a Near Zero Energy Rating is Desired.

Exceptional Energy Efficiency

Combining a Uniquely Nordic Design with Exceptional Energy Efficiency, the Tripled Glazed Viking DK88 Window achieves an Impressive U Value of 0.74 W/M²K. This Inward Opening Window Comprises Two Low-E Planitherm One Coated Panes and One Standard Pane, with Argon Gas Filled Cavities and a Warm Edge Spacer Bar, (SGG Swisspacer Ultimate). It Is 88 Mm Thick Overall without Alu Cladding or 121mm Thick including Aluclad.

Two Sash Gaskets Prevent the Internal Gap from Failure by Ensuring The Profile System is Highly Insulated, this also Minimises the Risk of Condensation Occurring Between the Window Frame and Casement.  

The High Performance DK88 Inward Opening Window has been recognised by the Passive House Institute in Germany as meeting the Stringent Requirements of the Passivhaus Standard.

Flexibility and Security

For those that have Travelled in Central and Southern European Countries such as Germany, France & Spain, the Inward Opening or ‘Tilt And Turn’ Window will be a Familiar Sight. In its Full Tilt & Turn Configuration, the Window Offers True Flexibility for a Wide Variety of Applications, it can be Swung Open Like a Door or Just Tilted at the Top for Ventilation with One Handle Controlling Both Operations.

When the DK88 Inward Opening Window is Tilted at the Top the Breeze is let in while Rain is Deflected Outwards. The Design Maximises Draft Free Ventilation, as Heat Escapes from the Top while Air Enters and Exits from the Sides. The DK88 Tilt & Turn Window has a Mechanism that Locks Into Place when Tilted, ensuring the Windows Security from any Potential Intrusions. All in All, an Excellent Choice for Situations where a Window Ideally Needs to be Left Open for Ventilation Purposes without the Worry of Security & Wet Weather Considerations.

When Fully Opened Inward, the Large Clear Opening can be used for Emergency Access and also Facilitates Easy Cleaning.

Clean, Scandinavian Inspired Design

The DK88 Inward Opening Window, gives a Clean and Elegant Appearance to the Exterior of a Property, as the Opening Sash can be Hidden Behind the Vertical and Horizontal Frame Sections. They also Allow the Use of External Features including Shutters, Fly Screens & Balustrades.

The Window is Available in either Timber or an AluClad Timber Finish, with the Minimalist Scandinavian Inspired Design Providing the Perfect Finishing Touch to a Project.

The Window’s Hardware comes from Leading German Manufacturer GU Uni-Jet, with the Hoppe Handles also being Engineered in Germany for the Best Performance. All Windows that can be Opened have a Handle in the Middle of the Jamb Relative to the Height of the Jamb. Tilt and Turn windows have a Handle on the Vertical Frame, while Tilt Only has a Handle on the Top Horizontal Frame.

Most of the time the Timber used is Nordic Edge Glued Laminated Pine Heartwood, from FSC Approved Sources which is used for Improved Durability and Dimensional Stability, we also offer in Meranti Hardwood or Oak Hardwood for an even more Durable & Beautiful Finished Window, The Engineered Timber is Impregnated with Teknos Wood Preservative Produced in Finland

Our Timber Window Range is available in any Opaque RAL Colour Imaginable, as well as Multiple Translucent Stain Colours. The Sash Gaskets are available in White, Grey, Beige, or Brown.

Optional extras

A Sun Protection Coating, Safety and Security Glass and Additional Sound Insulation can be Added if Desired. 

At a Glance 

Technical data of DK88 Window

Sound Insulation

Rw = 34 dB (-2;-5) – with standard glasses

Frame Depth

88 mm (121 mm with alucladding)

Material of Sash and Frame

Glue-lam pine; quality class A1-A3


50 mm 3-glazing, two Low-E glasses and argon filled


ROTO; Hoppe handle

Aluminium Cladding

Optional external alu cladding

Thermal transmittance

Uw = 0,74 W/m²K (1,23 x 1,48 m opening standard window)

Number of sash gaskets

2 sash gaskets (White, grey, beige, brown)


Installation Specifications

The Window can be Hung in Numerous Ways including Tilt and Turn, Tilt Only, Turn Only, Fixed Light and Shaped Frame Styles.

The Window can Open Inwards in Two Ways: Traditionally Side Hung (Turn), or with the Window Tilting Inwards from the Top of the Sash to Allow for Ventilation. Additionally, a Ventilation Restrictor Device can be Added to Fix the Sash Position after Tilting.  All our Inward Opening Windows are Available as a Double Sash French Casement (Flying Mullion). The Maximum Sash Weight is 100 kg.

It has a Frame Depth of 88mm (121mm Aluclad).


Sash Width

Sash Height

Tilt and turn opening:

394-1704 mm

500-2572 mm

Turn only

414-2054 mm

412-1322 mm

Tilt only

394-1704 mm

500-2572 mm

Tilt before turn opening

394-1704 mm

500-2572 mm


The DK88 Inward Opening Window is Suitable for use as a Fire Escape in all Configurations Except Tilt Only.

If you are looking to Increase Light Gain Into a Building, Structurally Dividing the Window with Mullions and Transoms Provides an Excellent Solution. Multi-Light Frames can be manufactured up to a Maximum of 2.5×3.2mtr in both Angular and Circular Openings, giving a Multitude of Possibilities for the Finished Design.

Nordic Quality as Standard

All Viking Windows are Produced in line with Vindus Industrien (Denmark) Technical Requirements, Considered the Gold Standard in the Window Industry, and come with a 5-year Manufacturers Warranty.

DK88 Triple Glazed wooden window:

Traditional, convenient, enduring, energy efficient, sustainable.

Drawings (PDF)

Drawings (DWG)

Passive House Windows Wooden and Aluclad Inward Opening DK88 Uw = 0.74 W/m2K


DK13 Aluminium Clad Window:

Modern, convenient, enduring, energy efficient, sustainable.

Drawings (PDF)

Drawings (DWG)

Passive House Windows Wooden and Aluclad Inward Opening DK88 Uw = 0.74 W/m2K


Opening types

Tilt and Turn Window

Tilt and turn

Our DK13 Tilt and Turn window opens inwards in two ways, traditional side hung (turn) and ventilation opening (tilt from top of the sash). Micro ventilation is also a possibility. A ventilation restrictor device can be added to hardware to fix the sash in position after tilting. Maximum sash weight is 100 kg. Also available as a double sash french window (flying mullion).

Side Hung Window


Our DK13 Turn only window opens inwards to one side (turn). Maximum sash weight is 100 kg. Also available as a double sash french window (flying mullion).

Tilt Window


Our DK13 Tilt only window tilts inwards from the top a little to allow ventilation. Maximum sash weight is 100 kg.


Fixed light



Multi light (with transoms and mullions



Our fixed lights and windows with mullions and transoms are a solution including a glass unit installed directly into the window frame, a good way to increase light gain to the inside of the building. Our product line also includes a wide variety of possibilities for structurally dividing frames with mullions and transoms. Single, multi-light window frames can be manufactured in sizes up to 2.5m x 3.2m

We also offer windows for angular and circular openings.


Teknos Aquatop and/or VRC

RAL; NCS and translusent systems:


Glazing Bar Options

COPY of SW11 aken 02 smallCOPY of SW11 puitaluaken 02 small


Links to Further Reading Below:

Product Data Sheet for DK88 Window

User Maintenance Manual

Additional information

Opening type


Hinge type

Glazing type

, , ,

Timber Type


U Value

Direct Line Timber Ltd. is a Limited Company Registered in Scotland and Trading for Over 25 Years

Company No: SC155945

VAT No: 693-8290-87

Contact Us

Feel free to contact us by Phone or Email

Login Your Account

Register Account

Registration disabled