buyer's guide
Aluminium
Aluminium frames are slim, allowing for more glass (and light) and less frame as aluminium is strong and quite rigid. Aluminium windows can support the weight of insulated glass without sagging and therefore bigger windows and window openings can be manufactured in this material.
Aluminium windows will last for a long time; quality windows lasting as long as fifty or more years and require very little maintenance making them competitively priced over the lifetime of the window. Metal frames also resist expansion so they are suitable for situations with strong sunlight or very damp weather where u-PVC and timber respectively would not perform as well. Aluminium frames will stay weatherproof long after windows made of other materials will have begun to leak.
Aluminium is the most abundant metal in the World and the third most abundant element. It is indefinitely recyclable and these facts along with the longevity of aluminium windows means it is a sustainable product.
Aluminium frames can be powder-coated with almost any colour both inside and out. The main disadvantage of these windows that they can conduct cold right through the frames although this has been minimised by manufacturers installing a polymer thermal break within the frame. Combining aluminium frames with very thermally efficient sealed units can mean aluminium windows still achieve high WER ratings.
Aluminium frames are slim, allowing for more glass (and light) and less frame as aluminium is strong and quite rigid. Aluminium windows can support the weight of insulated glass without sagging and therefore bigger windows and window openings can be manufactured in this material.
Aluminium windows will last for a long time; quality windows lasting as long as fifty or more years and require very little maintenance making them competitively priced over the lifetime of the window. Metal frames also resist expansion so they are suitable for situations with strong sunlight or very damp weather where u-PVC and timber respectively would not perform as well. Aluminium frames will stay weatherproof long after windows made of other materials will have begun to leak.
Aluminium is the most abundant metal in the World and the third most abundant element. It is indefinitely recyclable and these facts along with the longevity of aluminium windows means it is a sustainable product.
Aluminium frames can be powder-coated with almost any colour both inside and out. The main disadvantage of these windows that they can conduct cold right through the frames although this has been minimised by manufacturers installing a polymer thermal break within the frame. Combining aluminium frames with very thermally efficient sealed units can mean aluminium windows still achieve high WER ratings.
Composite
Composite frames have an inner timber frame covered with aluminium or plastic. This reduces the need for maintenance and keeps the frame weatherproof.
The introduction of more stringent energy efficiency standards in recent years has led to manufacturers developing advanced window systems. Different frame materials possess different strengths and weaknesses; metal windows are renowned for their durability but not for their energy efficiency, whereas for wooden windows the opposite is true. Very high levels of performance are being achieved by combining the relative strengths of different materials in one product, such as aluminium-clad softwood cores. Although still relatively new on the window market, aluminium-clad timber frames are expected to have lifetimes of in excess of 40 years.
Composite frames have an inner timber frame covered with aluminium or plastic. This reduces the need for maintenance and keeps the frame weatherproof.
The introduction of more stringent energy efficiency standards in recent years has led to manufacturers developing advanced window systems. Different frame materials possess different strengths and weaknesses; metal windows are renowned for their durability but not for their energy efficiency, whereas for wooden windows the opposite is true. Very high levels of performance are being achieved by combining the relative strengths of different materials in one product, such as aluminium-clad softwood cores. Although still relatively new on the window market, aluminium-clad timber frames are expected to have lifetimes of in excess of 40 years.
|
Energy Ratings (WER’s)
We are all familiar with household appliances such as fridges, freezers, washing machines and tumble dryers having an Energy Efficiency Rating and windows and doors are now similarly rated. Under a voluntary scheme, Window Energy Ratings are assessed by the British Fenestration Rating Council (BFRC), which is a wholly owned subsidiary of the glazing industry’s trade association, the Glass and Glazing Federation (GGF). The whole window (the window frame and the glass) is assessed on its efficiency at retaining heat. New windows should also keep out the wind, resist condensation and improve sound insulation. Window Energy Ratings (WER’s) use a traffic-light style A-E ratings label with those rated A to C also carrying the Energy Saving Recommended logo issued by the Energy Saving Trust. Ratings label can be useful to make an informed choice about the energy efficiency of windows you may be considering to install. (Windows installed in dwellings, under Building Regulations generally cannot be rated below a C rating but the ratings extend to cover windows used in buildings restricted by conservation legislation). Fenestra Glazing will give you WER ratings on all our products. |
|
Frames
There are various materials that can make up the window frames, each with different properties and styles and available in a range of energy ratings. Sometimes it will be purely personal choice that determines which you choose, matching an existing feature in the property, the size and shape of the aperture you are filling, your budget or the particular look that you are trying to achieve. Sometimes conservation will determine the material used. Before making any changes to your windows, please check with your local council or conservation officer for any restrictions.
There are various materials that can make up the window frames, each with different properties and styles and available in a range of energy ratings. Sometimes it will be purely personal choice that determines which you choose, matching an existing feature in the property, the size and shape of the aperture you are filling, your budget or the particular look that you are trying to achieve. Sometimes conservation will determine the material used. Before making any changes to your windows, please check with your local council or conservation officer for any restrictions.
PVCu
Un-plasticised Polyvinyl Chloride also known a uPVC – Frames made of u-PVC tend to last between 10-35 years depending on the quality of manufacture and the environment it is located in. PVCu is usually the cheapest material to make windows from and surpasses other materials as an good heat and sound insulator.
PVCu never rots, flakes, warps or rusts and apart from a wipe over with a damp cloth to keep it clean, requires virtually no maintenance making it very convenient and time-saving. However, if the frames aren’t cleaned regularly dust and dirt can become ingrained in the surface.
PVCu frames come in a variety of colours; it is possible to have one colour on the inside of the window frame and another colour on the outside.
The main complaint about PVCu aesthetically is that is not as versatile as timber and can look plain. If it becomes damaged it is not repairable and will require replacement of the entire frame. PVCu tends to have a higher carbon footprint than naturally occurring materials. It is a petroleum based product and therefore not sustainable and the manufacturing process requires stabilising with chemicals requiring intensive acquisition processes and create toxic by-products. Modern manufacturing methods and processes means it can be recycled but the process can be environmentally damaging so much ends up as landfill.
Un-plasticised Polyvinyl Chloride also known a uPVC – Frames made of u-PVC tend to last between 10-35 years depending on the quality of manufacture and the environment it is located in. PVCu is usually the cheapest material to make windows from and surpasses other materials as an good heat and sound insulator.
PVCu never rots, flakes, warps or rusts and apart from a wipe over with a damp cloth to keep it clean, requires virtually no maintenance making it very convenient and time-saving. However, if the frames aren’t cleaned regularly dust and dirt can become ingrained in the surface.
PVCu frames come in a variety of colours; it is possible to have one colour on the inside of the window frame and another colour on the outside.
The main complaint about PVCu aesthetically is that is not as versatile as timber and can look plain. If it becomes damaged it is not repairable and will require replacement of the entire frame. PVCu tends to have a higher carbon footprint than naturally occurring materials. It is a petroleum based product and therefore not sustainable and the manufacturing process requires stabilising with chemicals requiring intensive acquisition processes and create toxic by-products. Modern manufacturing methods and processes means it can be recycled but the process can be environmentally damaging so much ends up as landfill.
Secondary Glazing
Secondary glazing is generally made of slim, single glazed aluminium frames that slide or are hinged within an aluminium frame or tracks within a timber outer frame. The hardwood frame sits on the inside an existing installed window, attached to or close to the inner face of that window or a little inside so there is a gap between the two windows. The aluminium frames holding the glass are usually divided to the same proportions as the main window and either slide vertically or horizontally or are hinged to allow access to the main outer window.
Secondary glazing can be used to increase energy efficiency in a situation where replacement windows that would give greater energy efficiency may not be installed for conservation reasons (If secondary glazing is being considered for use in a listed building or within a conservation area, it is vital to seek advice from the local council or conservation office as secondary glazing is subject to restrictions.) In conservation situations, new windows can usually only replace like for like and therefore remain thermally inefficient. It may be that an existing original window is aesthetically pleasing or irreplaceable (such as original leaded light windows or stained glass Church windows) but may be very draughty and provide little security.
Secondary glazing may also be useful where windows are in good condition but not thermally efficient. Secondary glazing is often considered when householders cannot afford the cost of replacement windows but want to create a more thermally efficient environment.
Perfectly good windows may not be sufficiently soundproof. If this is the reason for considering secondary glazing, the type and thicknesses of the glass used can give improved noise reduction bearing in mind different thicknesses cut out different wave lengths. Laminated glass also improves sound reduction and there is now a new generation of acoustic laminated glasses. For additional reduction of noise pollution, leave a 4" (104mm) gap between the two windows and line the reveals (the walls and ceiling still visible between them) with acoustic tiles leaving a 3mm gap between the tiles and the outer main window.
Installing secondary glazing will help with thermal efficiency as the gap formed between the two windows is an effective thermal insulator however if the cavity is more than 4" (104mm) thermal currents within the cavity will decrease the insulation value. Where possible always try to draught proofing the existing outer window to feel the full benefit of secondary glazing.
Secondary glazing is generally made of slim, single glazed aluminium frames that slide or are hinged within an aluminium frame or tracks within a timber outer frame. The hardwood frame sits on the inside an existing installed window, attached to or close to the inner face of that window or a little inside so there is a gap between the two windows. The aluminium frames holding the glass are usually divided to the same proportions as the main window and either slide vertically or horizontally or are hinged to allow access to the main outer window.
Secondary glazing can be used to increase energy efficiency in a situation where replacement windows that would give greater energy efficiency may not be installed for conservation reasons (If secondary glazing is being considered for use in a listed building or within a conservation area, it is vital to seek advice from the local council or conservation office as secondary glazing is subject to restrictions.) In conservation situations, new windows can usually only replace like for like and therefore remain thermally inefficient. It may be that an existing original window is aesthetically pleasing or irreplaceable (such as original leaded light windows or stained glass Church windows) but may be very draughty and provide little security.
Secondary glazing may also be useful where windows are in good condition but not thermally efficient. Secondary glazing is often considered when householders cannot afford the cost of replacement windows but want to create a more thermally efficient environment.
Perfectly good windows may not be sufficiently soundproof. If this is the reason for considering secondary glazing, the type and thicknesses of the glass used can give improved noise reduction bearing in mind different thicknesses cut out different wave lengths. Laminated glass also improves sound reduction and there is now a new generation of acoustic laminated glasses. For additional reduction of noise pollution, leave a 4" (104mm) gap between the two windows and line the reveals (the walls and ceiling still visible between them) with acoustic tiles leaving a 3mm gap between the tiles and the outer main window.
Installing secondary glazing will help with thermal efficiency as the gap formed between the two windows is an effective thermal insulator however if the cavity is more than 4" (104mm) thermal currents within the cavity will decrease the insulation value. Where possible always try to draught proofing the existing outer window to feel the full benefit of secondary glazing.
|
Timber
Wooden frames have a lower environmental impact than u-PVC, especially those sourced responsibly. There are two schemes that can give peace of mind. One is the Forestry Stewardship Council (FSC) – their scheme enables wood to be tracked back to its source to ensure it comes from a responsibly managed forests. The Programme for the Endorsement of Forest Certification (PEFC) scheme identifies products made from forests managed in a way that helps maintain them, reduces environmental damage and ensures the product doesn’t contain any illegally logged wood. The PEFC also encourages manufacturers to use recycled materials in products. Being a natural product, wooden frames will require maintenance but developments in timber window design and finishing products mean that modern, high performance timber windows need minimal maintenance and potentially have a significantly longer life than PVC-u. As long as care is also taken in the choice of preservatives, paints and stains, timber windows are by far the best environmental choice. Many hardwood windows carry a guarantee of up to 30 years but with good maintenance and a sheltered position can last much longer with 50 years not being unusual, therefore the cost of the window over its lifetime makes it competitive with other materials. Wooden windows are often used in conservation areas where the original windows were timber framed. Good quality hardwood windows are made from the dense heart of a slow-growing timber species where the grain is closer. This minimises the wood moving as the atmospheric conditions change. Timber windows technology means that they can now be fitted with the latest security features. |
|
