It is important to understand that many factors affect the temperature climate in an apartment: the materials from which walls are made, ventilation, heating, the location of the building, its surface, convection, etc.
There is no single theoretical calculation of temperature changes in an apartment after the installation of new metal-plastic windows. But, based on experience, we can talk about an increase in the average temperature in the room at 5-7°C with the invariability of other parameters (heating, ventilation, etc.).
But pay attention to the fact that the installation of metal-plastic windows only contributes to reducing the loss of heat, but not its “production”. I.e. it will not be hot on a cold balcony after the glazing, unless a source of heat appears – air conditioner, heater, etc.