Worried who you can trust for your Home Improvements?
We have the solution so you can relax and get on with your life

Replacement Windows & Doors

The Double-Glazing Industry is a minefield!

Over the last few years stronger regulations have meant that the consumer is able to source more information, but in our opinion the way these products are marketed and sold still leaves a lot to be desired. False discounts, salesman’s promises and as a consumer, is the product really fit for my purpose? There are thousands of companies in the market place and all have different opinions use different products, install differently, pay their sales staff different commissions, say that their fitters only work for them, the list goes on.

The biggest issue the consumer has is getting price comparisons Like with Like as no two companies seem to be the same. Please, accept contrary to what any company tells you, windows and doors are not the same as there are many different grades of quality and many different glazing options hence why there is a vast difference in price.

FENSA (Part of the Glass and Glazing Federation) was established as a Competent Person Scheme (CPS) in response to Building Regulations for double glazing companies in England and Wales. As the market leader, FENSA is the largest and longest established Competent Person Scheme within the replacement window and door industry.

What does this mean for homeowners?

If you use a FENSA member, they can sign off their work without local authority involvement.

Benefits in Replacing Windows and Doors

Installing energy efficient glazing helps to reduce your energy bills and therefore reduce your carbon footprint. This will produce a warmer home and reduce heat loss therefore less draughts and cold spots. Installing energy efficient windows and doors keeps the heat in and insulates the property against external noise. This will also reduce condensation build up on the inside panes of glass.

How does energy efficient glazing work?

The Industry supplies normally two types of glazing. Double glazing which has two panes of glass with a gap in between of 16mm – 20mm. This gap creates an insulation barrier to keep the heat in. The gap is then filled with either argon, xenon or krypton gases to enhance the energy efficiency. Triple glazed windows have therefore 3 panes of glass and two gaps, however this does not mean the overall energy efficiency is better than double glazing. To evaluate efficiency, the industry is regulated by BFRC (British Fenestration Rating Company) ratings. The BFRC is the UK authority for independent verification of energy efficient windows and doors.  BFRC uses the well-known and well-respected ‘A++’ to ‘E’ energy efficient labels – like those found on fridges, freezers and washing machines.

What are energy efficient windows made from?

Energy efficient windows and doors come in a varied range of materials and a vast amount of styles. Performance levels of energy efficiency is based on three mail criteria areas. How well do the windows and doors stop heat passing through? How much sunlight travels through the glass area and how little air can leak in or out around the windows.


Low-E (low emissivity) is the most energy efficient glass. The panes have a coating of metal oxide on the internal pane which will let the heat and light in, but cuts down the amount of heat escaping.

Spacer Bars

To keep the two or three panes of glass apart spacer bars are used to create maximum energy efficiency. The most efficient spacer bars are ones with no metal in and within the industry these are known as warm edge. This eliminates the transfer of heat and cold reaction.

Frame Materials for Windows and Doors

Different frame materials have different energy efficient ratings.

The main 5 materials are:

PvCu know as uPVC window and door frames can last a long time and are suitable for recycling.

Wooden frames come in either hardwood or softwood and have low environmental impact. But they require regular maintenance. The main use for these frames materials is in either a listed building or conservation area, where local authorities will only allow replacement in like for like materials.

Aluminium or Steel window and door frames can last a long time. They are not so chunky as PvCu and can be recycled.

Composite frames are a hybrid. The have a wooden inner core and then are covered with either PvCu or aluminium to reduce the maintenance aspect.

Energy Efficient Doors

Building regulations state that installing a new door requires approval from the relevant buildings control body, and new external doors now generally contain integrated insulation to reduce heat loss and comply with the regulations.

Local Authorities

Before installing any forms of energy efficient glazing always check with your own local authority. They all have different takes on things and its important you conform to your local area. The three main issues to look at are: Do I live in a listed Building? Do I live in a conservation area? Are there any covenants on the deeds of my property removing the right of permitted development?

Listed Buildings

Listed buildings have tight controls on what you can change on the outside and sometimes the inside as well, depending on their grading. Old sash windows in historic properties can be protected not only for their appearance but also the materials and methods used to make them. But secondary glazing can be a non-intrusive way of insulated historic windows from the inside, and may be granted permission.

Conservation Areas

If you live in a conservation area or in a listed building, there may be restrictions on what you can do to your windows. These areas are of special architectural or historic interest, meaning that any work you carry out on your home must preserve or enhance the character of the area. This does not necessarily mean you cannot replace your windows, but might mean you will need to get windows that complement the character of the building and area. Double glazing can be made to look like your building’s original windows, but for any changes you do need to contact your local council’s conservation officer for guidance. There are many non-intrusive window insulation options available for historic homes such as heavy lined curtains, shutters, secondary glazing and sealed blinds. However, each historic building is considered individually so check with your local authority to see what options are available to you.

Building Regulations

Double glazing can be signed off by your local authority or by one of the competent person schemes. Once your installation is complete a certificate will be given confirming the installation has been fitted in compliance with the regulations by the individual or company who installed. Failing that you will require local authority approval and sign off.

The Glass and Glazing Federation (GGF) is a membership organisation whose members sign up to a consumer code, meaning you should receive excellent customer service. If you use one of their members to fit your windows but you are unhappy with the work, you will also be able to use their free reconciliation service.

Understanding energy ratings

Some window manufacturers show the energy efficiency of their products using an energy-rating scale from A++ to E. The whole window (the frame and the glass) is assessed on its efficiency at retaining heat. The scheme is run by the British Fenestration Rating Council (BFRC).


Windows that have an energy rating will have the u-value of the window displayed on the energy label. A u-value is a measure of how easily heat can pass through a material. Materials that let out more heat have higher u-values whereas materials that let less heat pass through them have lower u-values.

In some cases, windows with a higher energy performance rating might have a higher u-value than windows with a better energy efficiency rating. This might seem the wrong way around as lower u-values indicate better insulation levels. However, in these cases it will be that there are other aspects of the window that make them better overall such as coating used on the glass and the gap between the glass panes.


Replacement windows will be more airtight than your original frames, so condensation may build up in your house due to the reduced ventilation. If your house does not have much background ventilation, look for replacement windows with trickle vents incorporated into the frame to let in a controlled amount of ventilation.

If you start to see condensation building up around your windows, there may be a damp problem in your home. As a rule, damp occurs when there is inadequate ventilation, inadequate heating, inadequate insulation or a combination of these. If you’ve started to notice condensation in between the panes of glass in your double-glazing units then it is likely that the seal is broken, and the unit will need to be replaced.

Useful Sources of Information

There is a wide range of organisations out there that can provide further information on energy saving, reducing carbon emissions, and all aspects of the window industry from manufacturers to installers.

The government approved scheme that authorises installers to self-certify compliance for replacement windows and doors under the Building Regulations.

Glass and Glazing Federation
The trade association for the glazing, window and conservatory industry.

Helix Group
Includes a portfolio of leading brands brought together by a shared goal of continually improving standards which serve the home improvement, consumer protection, and industry standards sectors. Helix Group companies currently include: BFRC, FENSA, RISA, GGFi, Borough IT and Helix Training.

Offer independent and impartial Inspection and Auditing services to the Fenestration and Construction Industries in line with relevant legislation and standards. They are the sole provider of inspection services for FENSA Ltd.

British Plastics Federation
The trade association of the UK Plastics Industry and can help you to find a supplier of PVC-U framed windows.

British Woodworking Federation
The trade association for the woodworking and joinery manufacturing industry and can help you to find a supplier of timber framed windows.

Carbon Footprint
An online carbon footprint calculator.

Carbon Trust
An independent company set up by Government to accelerate the move to a low carbon economy.

Council for Aluminium in Building (CAB)
The Council for Aluminium in Building promotes the interests of the architectural aluminium industry and can help you to find a supplier of aluminium framed windows.

Energy Saving Trust
A non-profit organisation that provides free impartial advice on saving energy.

National Home Improvement Council
Provides ideas and advice on the range of improvement and maintenance activities that you could consider for your home.

Steel Window Association
Represents the great majority of UK steel window manufacturers and can help you to find a supplier of steel framed windows.

Register now and send us your requirements!

For 3 Fixed Price Quotations Free of Charge! Register your enquiry now!