Double glazing cost comparisons with single glazing are pointless. You need double glazing, even if it does cost more. If you are replacing a window the only sensible choice is to install double glazing.

Double glazing costs are higher than for single glazed windows, but you are getting a better window for your money. Even if you install a double glazed panel in a softwood frame it will be more energy efficient than a plain, ordinary sheet of glass.

Double glazing installers recommend that you do not install double glazed panels into softwood frames. It makes little sense to do this because you are putting a more expensive twenty years life window into a frame that will need replacing again in another ten years.

Choosing Your Double Glazed Windows

You have a choice of materials for the frames between aluminium hardwood and UPVC frames.

Aluminium Double Glazing

This first came onto the market in the 1970s. Shiny aluminium window frames look great, but aluminium does corrode and become dull over time. If you buy aluminium windows today they will not stay shiny.

Aluminium is a metal, so it is a good conductor of heat. It conducts the heat from your rooms to the outside world, no matter how much insulation is inside the frame. The frame will always feel cold and will be covered in condensation that will drip down and spoil your decoration.

Hardwood Double Glazing

Mahogany windows look great, if they are oiled every few years, inside and out. This is easier than painting, but probably still means you need to climb a ladder to reach upstairs windows.

Most hardwoods come from trees felled in rain forests, so buying window frames made from these woods means you are contributing to deforestation and global warming.

UPVC Double Glazing

Unplasticised PVC, UPVC and PVC are used interchangeably in the double glazing industry. UPVC has taken the lion's share of the new and replacement window market. Consumers love its clean, bright look.

UPVC window frames will still look just as good in ninety years time. The white will still be just as bright. They never need any painting or treatment. This is the main attraction they have to most homeowners and goes a long way to explain why more than 90% of windows have UPVC double glazed frames.

You can buy brown UPVC as well as white. This is useful if you live in an old property and need to fit replacement UPVC windows, but want to preserve the old, established look that your home has.

Double Glazing Benefits

Double glazing has many benefits. It reduces heat losses from your home, it eliminates cold spots near windows, reduces noise from outside and reduces condensation.

All of these benefits are increased if triple glazing is used. If you live in a very cold region then triple glazing will pay for itself. It is not generally considered worthwhile in most areas. It will make an extra improvement in every aspect, but will take longer to pay for itself through fuel savings than double glazing would.

Double Glazing Costs

The cost of double glazing windows is just part of the cost of maintaining your home. Yes, double glazing windows cost a bit more, but if you use UPVC window frames you will never need to do it again.

You can replace one or two windows at a time and pay for them out of savings rather than getting a loan. You will find that prices vary a lot more for this kind of small installation, so shop around more than you would for a whole house contract.

Double glazing costs per window vary according to size, window specifications and degree of local competition between different double glazing installers. UK prices for a standard four foot square window range from £200-£900 (GB pounds). Some double glazing installers spend massive amounts on advertising their product and salesmen's commissions. You pay for these costs in the price of double glazed windows from these companies.

You need to cost double glazing for yourself so you know what mark up your contractors are proposing. Contact a builders' merchant or builders' supplier and ask the price of a four foot square UPVC window, with double glazing. This is the cost a small, local double glazing installer will pay for the windows they fit. The cost of double glazing fitted is a lot more than the cost of the bare-bones window; how much higher will vary from one contractor to the next, depending on how much the contractor pays himself.

Ordering Double Glazing

If you ring any nationwide double glazed window company they will send a high-pressure salesman around. He will want to make an evening appointment, so you are tired and more likely to be bamboozled by his sales talk. He will be extremely reluctant to leave without you signing an order form.

This is why most people only have one double glazing salesman call, ever.

You can avoid high pressure sales tactics by dealing with a local double glazing installer, which makes sales through reputation, rather than using high pressure tactics.

If you want to buy from one of the large nationwide double glazing companies there are a few tricks you can use to manage the salesman:

· Avoid evening meetings by telling him you work nights

· Make sure that you are both present and that one person's sole task is to prevent the other from signing anything

· The salesman will want an open-ended meeting and will have made sure you are not rushing off anywhere after one or two, or three hours. Make sure you have somewhere you must go to after a certain time, but do not tell the salesman this at the start, or he will rearrange the meeting

· Walk out at the time you have said and drive away

· Arrange for a neighbour to come in as you leave to see the salesman out

These tactics might seem extreme until you have been on the receiving end of a double-glazing sales spiel.