Window frames are made using three main materials: wood, uPVC (a material called unplasticized polyvinyl chloride) and metal. You can also get composite frames, which usually feature a wooden core, covered by plastic or aluminium.
Wooden windows look great and are often the best choice for period properties, but they do require the most upkeep. You’ll have to keep on top of wood rot as well as chipped and flaking - completely repainting the frames from time to time is always a good idea.
Metal, uPVC and composite windows require little maintenance in comparison, so yes, they’re an easier option, but sadly, they don’t last forever. Past-their-best uPVC and metal windows aren’t pretty (although both can be painted) and the seals on double glazing can deteriorate, allowing moisture to get between the panes.
Swapping single glazing for double - or even triple - glazing will make your home warmer, quieter and more energy efficient. The older the windows are, the less energy efficient they’re likely to be. Original sash windows, for example, are notoriously draughty, but it’s possible to get double-glazed uPVC or wooden sashes, giving you a traditional look without being cold. You can also draught proof original sash windows with weather-stripping tape, or have them professionally draught proofed.
If you live in a listed building, changing the windows won’t be straightforward. You’ll need listed building consent from your local council’s conservation department, and they usually want the windows replaced like-for-like so the appearance of the building remains unchanged. Councils are also concerned about the appearance of buildings on ‘designated land’, which includes conservation areas and Areas of Outstanding Natural Beauty, and may place restrictions on replacement windows. Permitted development rights are often removed or curtailed for houses on designated land (flats and maisonettes don’t have permitted development rights), so you may need planning permission to replace the windows, or even to paint them a different colour.
All new windows must comply with building regulations, and you’ll need a certificate to prove this, especially when you come to sell. Your local council’s building control department can check and sign off the windows, or you can use an approved inspector, who does the same job but for a company. The easiest option is often to get the windows fitted by an installer registered with a competent-person scheme, such as FENSA. This means they can self-certify that the fitted windows comply with building regs - most window manufacturers offer a fitting service, which may be more expensive than using a builder, but is less hassle.