So windows have a dual purpose and dual settings too. And getting it right both inside and out and in terms of what works well and what looks right is an interesting challenge.

If you're considering changes to your windows then take time to assess what you'd like your window fitter to achieve. First it's important to recognise if the windows are a distinctive architectural feature or if they are anonymous, maybe even poor, badly chosen replacements. Take a look at the windows of neighbouring buildings - do your windows fit in with the style of the street? Are they made from appropriate materials? Is their size in proportion to the wall or would they look better if they were bigger or framed better?

Also their condition is important - get your window fitter to take a good look at them and tell you whether wooden window frames are suffering from rot or letting in more of a draft than necessary. Are they warped or well fitted? Is the glass cracked at all?

Then go inside and decide if any improvements are needed. Do the windows let in enough light? Do they need to be bigger, or does a plant outside need trimming to let in more light? Is there too much, glaring sunlight streaming in? Are the windows allowing you to enjoy a great view? Do you have enough privacy from the outside world? On the maintenance side is there condensation on the inside of the window? Can the windows be opened to let in fresh air? Is there too much noise from a road, aeroplanes or passers-by?

By answering all these questions you'll help define the positive and negative aspects of your windows and what work needs to be done by your window fitter.

You may just need a good decorator to strip off the paint from wooden frames and start again - if the windows are in good condition but just looking a bit scruffy then this will be the most cost effective option. It will also help prevent problems in the future by sealing the frames and keeping water out. If your windows are generally fine but a bit drafty a window fitter can fit better draft excluders around the windows - nowadays these can be very subtle, in fact virtually unseen. And if you have wooden sash windows that no longer function properly then a specialist window fitter can re-cord them, so they open and close smoothly.

If security is an issue then get your window fitter to fit window locks, especially on ground floor windows. Toughened glass and double glazing also help keep intruders out. And if you're really worried then metal bars could be installed - again these are most commonly found on lower ground and ground floor windows.

You may need to replace the existing windows because they are worn out or rotting. Depending on the style of your building you can opt for wooden frames (this is aesthetically the best option in a period home) or UPVC (requiring no ongoing maintenance). If lack of light is a problem then consider creating a new or bigger window opening, but look first whether there are obstacles such as a large tree or unnecessarily heavy curtains that could be replaced with something less bold. If you are getting too much light, think of ways to shade a room - light sheer curtains can cut out glare. Planting a tree or installing a canopy over a window can protect you from too much sun. Also look into frosting windows for both privacy and less direct light.

Finally on the inside don't forget that your window dressings have a big impact on the look and feel of your room. For a modern look replace thick curtains with blinds or wooden shutters. To create a sumptuous, luxurious feel go for beautifully patterned or textured curtains. For a bit of fun paint the window frames a bright colour or plant up window boxes to brighten up the view.

Windows are a vital part of defining the character and feel of a building. Small alterations or a complete change can really improve your home.