The style and type of double-glazed windows you choose will have significant impact on the value and kerb appeal of your home. It's important to know what options you have, and which will work best with other design and functionality aspects of your home. Getting double-glazed windows for your entire home will require a considerable financial investment, and so you should research well to ensure you've made the best decisions. These are some things to think about as you shop around.

1. Cost

For many homeowners, cost is often at the top of their list, but this shouldn't be the case. It's always advisable to consider your functional requirements, and then plan ahead to ensure you have enough to give you the best windows. After all, it doesn't make sense to spend a little less for something that could last years, and then spend that time wishing you'd invested in the more-expensive option that would have made you comfortable.

Of course you know to get several quotes from different companies, both big-brand and local suppliers/installers. The former will likely offer cheaper prices and have more experience, but you can get faster and more personalised service from the latter. There are other factors that will impact the final price of your windows:

• Window material – aluminium frames are most costly in initial costs, while wood has higher maintenance costs. You can choose uPVC which is cheaper and commonly-used. Special finishes may also be more costly

• Labour – you can expect a smaller bill if you buy windows and install them yourself, but this means you have to be handy. Labour costs will include removal of old windows, site preparation and installation of new windows.

• Design elements – choosing non-standard colours, sizes or designs may also affect your final price, and so will non-standard add-ons which will be highlighted below in detail.

2. Non-standard add-ons

You should consider what exactly you need your windows to do for you, bearing in mind that most add-ons attract an extra charge. It's often better to discuss this beforehand and then send a specification list when searching for quotes. Below are some parameters you should consider:

• Glazing – double-glazing is most often used for residential homes. Triple-glazing may be great on paper, but it costs considerably more. You should only consider this if you live in extreme climatic regions, as you'll get actual value-for-money

• Safety glass – you can get tempered or laminated glass for additional cost. Tempered glass is treated to increase strength, and breaks into tiny granules that won't cause injury when stressed. Laminated glass holds together when it shatters. If you can't afford this for the whole house, start with children's rooms

• Energy efficiency – there are special coatings like "low-e" glass to improve heat transfer. In addition, the space between the glass panes can be filled with an inert gas like argon to further reduce heat transfer. You can also increase the gap between the two panes, with wider gaps costing more than smaller gaps.