Preservation of architectural heritage and modern window technology don't have to incompatible!

Timber or plastic windows?

Selecting the most suitable windows for buildings on the historical register can often pose a dilemma. On the one hand, modern requirements for thermal and noise insulation need to met, while, on the other hand, the original appearance of the building needs to be preserved.

Economy is the highest priority

In current times, where public coffers are empty, the most important factors are longevity and ease of maintenance. These criteria are considered when deciding to install windows. The pros and cons of wooden frames and plastic profiles should be directly compared, the purchasing costs and maintenance costs over a period of several years considered, all without losing sight of the architectural demands. 

Structural and financial concerns

The structural stress placed on the window is often extremely important. The wind load to which the window is subject plays a decisive role in this respect. It is often only possible to achieve the specified values through the use of additional structural reinforcing. The heating costs on preserved historical buildings such as schools is another important cost factor. That is why thermal insulation is especially important when renovating such buildings.
  

Safety first

Public buildings - especially schools - are subject to high safety standards, and these must also be met by the windows. The windows must also often serve as escape exits in an emergency. This requires selection of windows without a fixed mullion to achieve the required escape exit width.

Conclusion

Use of plastic windows is, in part, negatively evaluated by the Office for the Preservation of Monuments and Listed Buildings (Landesamt fr Denkmalschutz). Nevertheless, plastic windows are used with increased frequency in listed buildings, due to their positive characteristics.