Design: In a glass of their own

The world has moved on from the time when adding a conservatory to your property was thought to be the height of sophistication. While they are still an excellent way to increase your living space and add value, their designs have lamented in the past. Stylish types are looking for an alternative to sticking an ugly, poorly insulated aluminium frame onto the back of their houses; something contemporary and eco-friendly that will connect the main living space with the outside.

Most of these new conservatories are designed by architects with prices to match, but one company, Glassbox.co.uk, has come up a with a modular design that can be installed in around two weeks and costs from £18,000 – which, if you regard it as an extension to the house, makes it a good price. An extra room can add up to £30,000 to the asking price of a property, although be aware that you should never spend more than 10 per cent of the value of the entire house or you may not get it back when you sell.

Installing a frameless glass extension will bring the house and garden together, increasing the sense of space and light. By using proper glazing and conforming to building regulations, the traditional problem of the conservatory being too hot in the summer and it sucking all the heat from the house in the winter will become a relic of the past.

Zig Chowdry, the founder of Glassbox.co.uk, explains: "I come from a background of selling conservatories and I started to notice that while everything in life was starting to look really modern and space age, the conservatory hadn't moved on at all. Even my vacuum cleaner looks like something from Star Trek. But people were still putting up cheap Victorian and Edwardian pastiche conservatories. The cheaper they get the worse they look.

"These conservatories are too cold in winter and too hot in summer as well as being so bright that people spend even more money on blinds. It's completely stupid. They have bought a really cheap conservatory and then have to spend a fortune correcting its inherent design faults."

So Chowdry started hunting for alternatives that would be more eco-friendly but still fulfil a desire for something modern and stylish. He came up with the modular glass box. It has three glass walls and a solid roof with large windows to let the light flood in.

"These are completely efficient in terms of insulation, so they are very green. When I began my research I found these amazing architect-designed glass boxes or frameless conservatories but they cost £150,000, which most people can't afford. There had to be a way of creating an affordable, eco-friendly glass box that didn't cost the earth.

"Ours start at £18,000 (plus VAT) for one that measures 11ft by 11ft. It can go up in under two weeks including the groundwork and electrics and then the customer arranges their own flooring and decoration."

Rob Sterry, of Paul Archer Design, believes those in period properties shouldn't be afraid of a contemporary glass extension. "They work on any type of property, partly because they are frameless so it's as if it isn't there. People are really moving away from the mock Victorian style. It's partly to do with the desire for more open-plan living and creating a year-round room.

"The trend is towards a space that brings both the outside and inside together and advances in technology and insulation mean that they can be really efficient without losing out on style."

Starting costs for an architect-designed frameless extension are around £70,000, which will include the landscaping around the garden, for example using matching floor tiles in the extension and the outside to bring the two areas together.

For planning advice, visit www.planningportal.gov.uk; online help about building an extension: www.growyourhome.com; to find an architect: www.ribafind.org; Glass box designs: 01733 233 000, www.glassbox.co.uk; Paul Archer: 020-7251 6162, www.paularcherdesign.co.uk

Furnishings

*If you've shelled out on a fabulous glass extension, the last thing you want to do is fill it with old fashioned rattan furniture. Almost anything modern will go, but consider a Sedi tub chair or these ticking cushions (inset) from Toast to create a modern, more relaxed style. Supatra also make modern rattan furniture that won't drag your modernist extension backwards.

*You could also use reversible material to upholster a sofa or chair, which will give you the benefit of a different look for summer and winter.

*Remember it will be the main point of entry from the garden so the floor needs to be hard-wearing and not show the dirt – slate is a good, contemporary and affordable choice.

*It may not be an original orangery, but a good selection of large plants will always help unite the space with the garden outside and add to the feeling of relaxation. Choose large, lush plants with a jungly feel and arrange them in big pots.