Energy Efficiency Benefits Of Double Glazing Upgrades

Back in 2016 the then Department for Energy and Climate Change (DECC) published a buyers guide to “choosing the best windows and glazing for your home”. In it they stated:

All properties lose heat through their windows. But energy efficient glazing, and other energy-saving measures, keeps your home warmer and quieter as well as reducing your energy bills.

They went on to state that:

18% of heat loss occurs through windows
Across the UK, around 7% of households have no double glazing
Heat is lost through single glazing around twice as fast as through double glazing

Back then the focus was on the remaining 7% of households that still had no double glazing and over the last few years things have improved somewhat. In 2022 it was officially reported in the English Housing Survey 2022-2023 that 88% of homes in England had full double glazing, up from 79% of homes in 2012.

We’re never going to get to 100% because there’s always going to be different regulations for Listed Buildings and other anomalies but it’s looking good right??? We, at Energy Efficiency Matters, would question that statement!

Double Glazing Regulations Through The Years

The building regulations was an act bought in 2002. This act states that any replacement windows put in after April 2002 must conform to certain energy efficiency ratings. Specifically, they must have a minimum energy performance rating of ‘E’.

Put in simplistic terms this meant that all new build homes (built after April 2002) must have double glazing installed to conform to EPC ratings given by the local authority.

It’s not illegal to have single glazing or windows that don’t meet the current regulations – it just means that if you are looking to replace your windows under the current building regulations, they must now have a window efficiency rating (WER) of a minimum of ‘B’ and a U-value ( term for the rate of heat transfers through the window – the lower the number, the better), of 1.4 W/m2K or lower.

In terms of new build homes the regulations are even tighter – new windows must have a U-value of no more than 1.2 W/m2K and a WER of B or better.

Where We Are Now

So, all homes built after 2002 should have double glazing installed and all homes that have had replacement windows since this date should also have double glazing installed. That said, technology has improved and regulations have tightened so there could still be a benefit in upgrading existing windows.

The big issue though is with homes built pre-2002. These houses may well still have double glazing and hence still appear as a positive number in Government figures but the glazing could be up to 50% less efficient and a long way off meeting any current regs.

Just How Big Is The Problem

The Glass and Glazing Federation (GGF) along with British Glass published a hard-hitting report towards the end of 2023, entitled ‘A Window of Opportunity’. It’s key findings:

80 Million Windows Need to be Replaced Across the UK
UK homes are the worst in Western Europe for heat loss
98% of windows do not meet current building regulations
New windows can save homeowners up to £395 per year off their energy bills
80 million home windows need to be replaced if the UK hopes to meet the government’s net zero targets.

Startling figures we think you’ll agree!

The report went on to say that, when it comes to heat loss in a home, the UK currently has the least efficient housing stock in Western Europe and has seen one of the worst carbon reductions of all sectors since 1990.

The report demonstrates that replacing older windows with a double glazing upgrade to new windows that meet current standards can reduce heat loss in an already insulated home by half, from 44% to 22%.

Other figures that are certain to shock millions of homeowners are:

80 million windows would benefit from being replaced now.
The UK’s housing stock is the worst performing country in Western Europe in terms of heat loss, and three times less energy efficient than Germany.
Double glazing installed pre-2002 is in approximately 23% of the UK’s current housing stock and is 50% less energy efficient than new windows to current standards.
22% heat saving could be achieved in properties that have already been insulated to best practice if pre-2002 windows are replaced.
Homes fitted with new windows to current standards could see a saving of up to £395 per year.
24% of the UK’s carbon emissions come from the residential sector.
Replacing pre-2002 double glazing with new double glazing to current standards is the equivalent of taking 1.88 million cars off the road.

We would recomend that you read the report – it’s not long and easy to understand:

Download the report: A Window of Opportunity >

The Government Approach To Double Glazing Upgrades

Double Glazing feels like a forgotten energy efficiency measure under the various government initiatives and incentives supporting the drive to net zero.

Indeed, within their flagship ECO funding, whilst double glazing does appear as a measure it’s hidden away under “Insulation Measures”.

To stand any chance of getting funding for double glazing whatsoever an owner occupier home must be in a starting SAP band of between D-G and adhere to the other required base eligibility criteria. Meet the requirements and ECO sections state:

5.46. Window glazing can be installed as either ‘single to double’ or ‘improved double glazing’.

5.47. ‘Single to double’ is the replacement of single glazed windows, to glazing which meets the current building regulations. This may be double or triple glazing.

5.48. ‘Improved double glazing’ is the replacement of double-glazed windows that do not meet current building regulations. Such windows can be replaced with double or triple glazing that does meet current building regulations.

However, they go on to state that:

“While a replacement window glazing measure is eligible under ECO4, we stress that it is up to the energy companies to determine which retrofit projects and measure packages they choose to fund.”

This means there’s no clear and obvious grant funding or incentive to upgrade double glazing to current regs – even if your windows were installed pre 2002 yet the benefits could be considerable.

What is good to see is a collaborative industry addressing the issue and taking action. The ‘A Window of Opportunity’ report provided easy to digest access to the facts and the message is being driven home to all who will listen – even behind the doors of Number 10 itself.

Chris Beedel, Head of Advocacy at the GGF, said:

“We are in continuous discussion with the government about net zero targets and the positive contribution that would be made if older double glazed windows were to be replaced. As the government looks to achieve net zero, it is clear homeowners and our industry have a vital role to play.”

“We are well aware of the current state of the economy, and as the government requires higher energy efficiencies from new windows, there needs to be real incentives for homeowners to make the necessary change to new windows.”

Chris continues:

“The residential sector currently contributes to almost a quarter of the entire country’s carbon emissions. This needs to change – reducing emissions from households, and therefore improving glazing, is crucial in helping reach net zero, which we are all committed to.”

Natalie Little, President of the GGF, said:

“This report may come as a surprise to homeowners, and the government. In the last two decades, replacement window and door technology has developed enormously through manufacturing and improvements in plastics, glass and metals”.

Natalie, who also acts as Commercial Director of truhouse., her family’s home improvement company based in Stroud, Gloucestershire, added:

“Today’s double and triple glazing is light years ahead of what was available 20 years ago with windows installed today performing 50% better than old double glazing and 70% better than single glazing. Almost a quarter of the UK’s homes have double glazing that is at least 20 years old and therefore doesn’t meet today’s standards and would benefit from immediate replacement. It’s like driving a 20-year-old car. It will get you from A to B but will not be as fuel and emissions efficient as a new car.

Standards are constantly under review and we await the government consultation on the Future Homes Standard for new build homes which could see a move to triple glazing and much more stringent energy efficiency requirements.”

Double Glazing Upgrade As An Energy Efficiency Measure

If you’re looking at improving the energy efficiency of your home then don’t ignore the double glazing. Just because your property may be one of the Governments quoted 88% of homes which have full double glazing installed doesn’t mean to say it can’t be improved significantly.

Remember the key findings of the report … 98% of windows do not meet current building regulations, new windows can save homeowners up to £395 per year off their energy bills and 80 million home windows need to be replaced if the UK hopes to meet the government’s net zero targets.

So, check what you’ve got, check when it was installed and call in an expert to give you an assessment of just what the impact of a double glazing upgrade in line with current regs could be … you may be incredibly surprised.