As good as new!
Your old windows may still look good from the outside. However, they often lead a lot to be desired when it comes to insulation, meaning that you are literally throwing money out of the window. Rising energy costs are doing their utmost to make sure your heating bills go up and up, year in, year out. Replacing your old windows will be a decision you won't regret as the investment only takes a few years to pay off.
Are your old windows secure enough? Will they withstand any attempted break-ins? The majority of break-ins have been proven to start at a window. What more reason do you need to start thinking about break-in-proof windows – before this problem affects you, too. The best safety components available for windows are the safetec inside and bonding inside systems by aluplast.
EnEV: If you are planning to make major structural changes (facade, windows, roof) during a renovation project in Germany, then you need to consider the requirements of the German EnEV (Energy Conservation Regulation). To be precise, the current EnEV must be applied if over 10% of a building (based on the surface area of the entire building) is being changed. In this case, the maximum energy consumption for a house/flat must be observed. This corresponds to a maximum U-value of 1.3 W/m²K for windows.
KfW: The funding programmes offered by KfW (a German bank specialising in development) set out a minimum target for energy efficiency. The values specified in the German EnEV (Energy Conservation Regulation) act as a reference though more funding is available for more significant improvements to a building's energy efficiency. If you are receiving funding from KfW, it is important to note that a maximum U-value of 0.95 W/m²K applies for windows. In general, walls have to be better at retaining heat than windows so that condensation collects on windows instead of the walls, where it can lead to mould (see www.kfw.de).
Passive house: Relatively speaking, not many old buildings are renovated to passive house standard at the moment, though the German government are hoping that this will become standard over the medium to long-term. In the window industry, aluplast is the only system provider to offer a narrow construction depth of just 70 mm, which is certified according to the ift (German Institute for Window Technology) passive house standard.