Architectural designer, Oliver Heath, has transformed a typical 1960s detached house into an energy efficient family home with the aim of reducing its carbon footprint from 10 tonnes per year to 2.5 tonnes.

Key to the improvements has been the replacement of the original UPVC windows with VELFAC 200 series double-glazed, argon-filled aluminium windows and sliding window doors.

At the front of the property three new windows have replaced the original UPVC windows while a fourth takes the place of the original garage door. At the rear, a more dramatic transformation has occureed with the two ground floor windows ripped out and exchanged for two sets of 2.57m wide, floor-to-ceiling glass sliding doors that lead from the living spaces into the garden. The only interuption is a load-bearing column that acts as a central divide.

"We've increased the area of glazing on the ground floor by 200% which has drastically increased the amount of natural light", says Oliver. "Not only does it make the house more enjoyable to live in, from an environmental point of view it means that we are much less dependent on artificial lighting". The house, which is orientated eastwards, also now benefits from increased but controlled levels of solar gain. "The sun enters in the mornings and afternoons achieving a very comfortable internal temperature", Oliver says.

Increased glass ratio

The primary goal was to enhance the amount of natural daylight entering the building, while minimising major structural changes to the existing opening in order to curtail costs. Although the outer dimensions of most windows have remained the same, the difference in the width of the combined VELFAC mullion and frame compared to a UPVC system has greatly increased daylight levels.

Air tightness

The entire building, including the windows and sliding doors, needed to be extremely air-tight to minimise heat loss and to maximise the effectivess of the heat recovery system. The seals on the sliding doors are more reliable than those on folding, sliding systems, while the sealing system and arrangement that is installed around VELFAC products further prevents leaks.

Low maintenance

VELFAC windows are of composite construction, meaning they are made from a combination of materials. While timber, a natural and sustainable insulation material, is used for the internal construction, the external aluminium sash enhances the window's performance and increases its service life. Whereas a timber window requires periodic repainting the external aluminium sash requires almost zero maintenance, needing only to be cleaned occasionally. Furthermore, aluminium is more durable than timber, inceasing the life expectancy of the window to in excess of 40 years.

By exploiting the beneficial properties of both materials in this way the composite design enhances the performance of the window whilst reducing its environmental impact as less resources and energy are used both in maintaining the window and in its replacement due to the extended service life.


The clean architectual lines and contemporary quality of the VELFAC designer windows suited the age and era of the house. They helped bring the building up to date without being too obtrusive or too stylised. "We've literally had people stopping outside and commenting on how great the windows look", says Oliver.

As the project was completed in 2010 the performance of the house is yet to be measured. "It's too early for calculations and statistics, but on a human and emotional level I am really pleased with the VELFAC products", says Oliver. "They look great and function exceptionally well, making this a very comfortable house to live in".

For further advice on VELFAC aluminium windows for your home contact VELFAC Direct - 01536 313552.