Window between past and future

Denkstil, the next generation

Next generation double sash box window for the renovation of heritage and listed buildings. With the development of DENKSTIL windows our aim was to create a double sash box window which not only fits into the heritage environment but also fulfills state-of-the-art practical and thermal insulation requirements. With the aggravation of thermal insulation requirements many historic windows, which are mainly double sash box windows, fall a victim to renovation, and one of the main reasons of this is that until recently there wasn’t available a solution which both corresponds to todays requirements, thermal performance characteristics and aesthetic aspects. Unfortunately the result of this very often is that problems like mould, urban landscape and aesthetic problems, and also legal dispute between co-owners because of the decrease in the value of the building.

Our products mean a down-to-earth and quality controlled alternative for the changing of the windows during renovation of heritage and listed historic buildings both for private person and institutions.

About us

Our passion is architecture
and renovation of historic buildings. Our mission is to create and preserve value.

DENKSTIL windows are developed with the joint work MG Építész Kft., an engineering company with R & D activities and a three-generations family business, T-Bútor Kft. in Olaszfalu, Hungary.

MG Építész Kft. (MG Architects) was founded in 2003. The company offers a wide range of services, including complex construction services, building energetics and court expert services from advisement to construction. Among the activities of the company planning and R&D has an increasing proportion, and also is the main contractor of a growing number of innovative, large-scale and individual buildings.

The company is market leading in the field of court expert services in Hungary, and thus has an expansive experience related to the problems occurring in the construction process. MG Építész is dealing with the question of the improvement of building structures since its foundation, concentrating on the question of energy- and environmental efficient planning and construction.

renovated buildings

windows changed

years of professional experience

finished plans

Why to choose Denkstil?

Historic buildings make up a significant percentage of total building stock in many European countries, either in Hungary, or in Austria, Germany etc. These in Hungary were mostly built between 1850 and WW1. Windows and doors are among the most characteristic elements of these buldings, and these have a basic role not only in the operation of the buildings, but also determine their appearance. However, these historic windows, which are mainly double sash box windows, often fall a victim to renovation, and one of the main reasons of this is that until recently there wasn’t available a solution which both corresponds to todays requirements, thermal performance characteristics and aesthetic aspects. Building stock potentially involved is huge, as not only in the area of historic Hungary but also in all small towns and bigger cities of the former Austro-Hungarian Monarchy many downtown buildings, public institutions and schools might be affected. 

This is the challenge to which Budapest-based MG Építész KFt. responded, and, based on their three decades of experience in engineering, architecture and professional expertise of architecture, developed Denkstil window system. The production of the windows is based on a scientific research and innovation process and several tests of the prototypes.


Historic design, up-to-date materials

Our double sash windows not only preserve the looks of historic buildings but also fulfill both the practical and thermal insulation requirements of our era.

State-of-the-art insulated windows

Our windows fulfill all todays requirements of thermal insulation.

Preserving the historic scene

Double sash box windows are inseparable elements of the facade of historic buildings. During the changing of them we preserve the original historic street view.

Historic looks, state-of-the-art technology

In the last few years changing windows of heritage buildings has become a mass demand. Renovation of these windows, which are mainly double sash box windows, is realised usually so that carpenters make the new windows similar size as the original ones, however new glazing is heavy thermal insulating glazing instead of the original, lighter 2 mm version. Because of this wrong sizing structures may warp, and it often happens that a year after installation they can not be opened and windows sag. This leads to guarantee disputes stressful for both parties. These custom-made windows are expensive, however they still fail to exploitate technical possibilities and they can not serve users’ needs.  

Contrarily however, our Denkstil technology fulfills optimum points of technical, economical and conservation of heritage requirements, while observing also legal and environmentaly requirements.



Windows with long life expectancy

All of the wood processed by us comes from sustainably managed forests. Wooden surfaces are treated exclusively with environment friendly products or bio-oils. Because of the excellent quality thermal insulated windows energy consumption can be lowered, while window fittings and parts are reusable. Rubber and caulk systems are free of formaldehyde.

New innovative solutions

Our third generation carpenter workshop is responsible for the technical implementation. Here also stat-of-the-art CNC technology is used besides traditional methods.

State-of-the-art materials, in the spirit of the past

The product created is ideal from the technical and economical point of view according to the highest existing standards of today. DENKSTIL windows eliminate completely the regularly occurring technical problems of the double sash box windows used during the renovation of heritage buildings.

THE TECHNOLOGICAL DEVELOPMENT REALISED means that the traditional appearance is recreated not by using traditional materials and technologies, but by adapting all accessible technological and engineering possibilities. As the result of DENKSTIL project double sash box windows, with both sashes opening inward, are developed. These fulfill the requirements of the building authorities related to the replacement of windows of heritage buildings.

Certified window

By the product placed on the market all interested parties (clients, building contractors) obtain certified double sash box windows with both sashes opening inwards.

Thermal insulation standards

Furthermore, the windows developed not only fulfill thermal insulation standards but also eliminate problems which are prevalent today: thermal bridge, moulding, and the loss of the original appearance.

Free of thermal bridges

In the cases of traditional homgenous (brick) wall buidlings, after replacing the original windows with single sash new windows, thermal bridge forms in the wall structure, which means that during winter the temperature of the inner wall surface around the window will be often below dew point. It is guaranteed thet Uw value of our double sash Denkstil windows reaches the required 1.1-1.3 W/m2K and thus this problem will not occur.


Our Denkstil windows are developed according to standards of heritage conservation and long-term reliability is guaranteed.

Elimination of warping

Thanks to our Denkstil windows warping and distortion of the structure, caused by the gauging mistakes (building in too heavy thermal insulating glass into the structure) can be eliminated.

Fulfilling today’s requirements

Furthermore, new windows will be able to fulfill today’s user needs. They are produced with environmentally consciuos coating on the inner surface, and UV resistant coating on the outer surface. They are also windproof and there is also a possibility to choose hopper window design or sunguard coating.


Our next generation DENKSTIL double sash box windows were built in Újfalusy Márton Guesthouse at Zirc, and thus historic appearance of the building was preserved. Also Denkstil-style windows realised according to the plans of our architecture office were built in and fulfill their roles entirelly the headquarters of Hungarian National Bank in Budapest and Bagolyvár Inn at Zirc. Changing of the windows of the inner facades of Nyugati Railway Station in Budapest is in the process, here also double sash box windows produced according to the plans of our company are being built in.


Nyugati Railway Station

Complete renovation of the roof, changing of windows and doors



Hungarian National Bank

Changing of the windows and of the outer facade



Bagolyvár Inn, Zirc

Real-estate development, complete renovation



Újfalusy Márton Guesthouse

Real-estate development, complete renovation


Let’s renovate our built heritage together!

In case you need any further information or we have raised your interest, please contact us via the following contact details or using the form.
+36 20 8230795
+36 30 7468127


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