When it comes to replacing your windows, you’ll ideally want to be looking towards double and triple glazed units. They’re by far the most energy efficient options on the market and will help you cut heat loss and reduce expensive bills.
For properties in conservation areas this may not be possible and something known as secondary glazing could be your best option. This is where a second pane of glass is installed on the inside of your original window, rather than replacing the whole unit.
Replacing Windows with Double Glazing
Double glazing is by far the most popular replacement window option and this is evident with over 80% of British homes having this insulation measure in place.
Double glazing is manufactured from two panes of glass, separated by an inert gas spacer. The gap itself has changed over time, but today industry advice is around 16mm. The gas used is energy efficient and prevents heat passing through and exiting the home.
You’ll want to choose double glazing with the best energy rating possible. Not all double glazing is created equally and the efficiency will be measured by a number of factors including:
- How much heat passes through the unit
- The amount of sunlight allowed inside
- Air leakage around the frame.
The energy efficiency of your windows will be measured from A to G, with A the most efficient. The scheme is run by the British Fenestration Rating Council and covers the whole window unit, not just the pane.
The double glazing’s efficiency will be determined by the different components of the double glazing listed below.
Glass
Glass is one of the key contributing factors determining the efficiency of the double glazing unit as a whole. If you’re keen to have the most efficient glazing type you’ll want Low-E glass (low emissivity). This is uniquely manufactured with an invisible metal oxide coating, allowing light and heat inside, but preventing heat from escaping.
Gas spacer
Then there’s the gas spacer, sandwiched between the two panes of glass and responsible for preventing heat from passing through the unit. Efficient gases are motionless and there are three common choices; Argon, Xenon and Krypton. Argon is typically the most popular.
Standard Pane Spacers vs. Warm Edge
The pane spacers are located around the whole unit and hold the two panes apart. Warm Edge technology refers to the edge construction of a double glazed unit that conducts less heat or cold than traditional windows and standard construction double glazed units.
Standard units are constructed with an aluminium spacer to hold the glass apart. However, aluminium is highly conductive and also has an exceptionally high thermal energy loss.
Warm edge spacer bars are usually made from a fibreglass reinforced insulation material. An ultra-thin foil lining acts as a barrier to the gas or air trapped within the cavity. Warm edge spacers are available in an array of colours and can be used for Georgian or Victorian style double glazed sash windows.
Comparatively, double glazed windows fitted with warm edge spacers are up to 65% warmer on the inside. This helps to improve the thermal efficiency of the window and reduce the risk of condensation.
Frame material
The frame material is one of the key contributors to the efficiency of your windows and again, there are three choices; uPVC, timber and aluminium. Each has its benefits and for many it’s a popularity contest based on looks and costs. From an energy efficiency standpoint though, the clear winners are uPVC and timber frames as these retain more heat in the home.
When is Double Glazing Not Permitted?
We’ve already touched upon this earlier in the guide, as properties in conservation areas or listed buildings are restricted on what can and can’t be done. To preserve the special architecture or historic interest, you must comply with legal requirements governing the installation of double glazing.
Double glazing must therefore, complement the character of the building. Otherwise, it could be outright refused when you seek permission. This isn’t to say windows keeping the character of the building will be approved, but there’s a greater chance by proving your commitment to maintaining the traditional appeal.
If planning permission is refused for your double glazing, there are various options to consider for improving energy efficiency. This includes:
- Draught proofing
- Secondary glazing
- Heavy curtains
- Blinds
- Shutters
To check if your property is in a conservation area or in fact a listed building, see your property deeds or contact the local council. They’ll be able to advise you on this.
What are the Major Benefits of Double Glazing?
It’s not just from an energy standpoint double glazing holds favour among homeowners. There is a range of significant benefits to ensure an investment in replacement windows is worthwhile and includes the following:
• Reduced heating bills
Energy bills have been on the rise for years. In fact, since 2004 the average household bill has more than doubled and homeowners are now spending in excess of £1,300 each year on their dual fuel expenses. For that very reason, double glazing has become popular and will help to reduce your heating bill by up to £160 on an annual basis.
• A reduction in your carbon footprint
In light of the energy saved with double glazing, you’ll start to become more eco-friendly. The less heat lost in the home, the fewer carbon emissions will be produced because of a need to replace the heat. If your home is cold, you’ll turn up the thermostat. Double glazing locks heat inside the home, so there’s no need to increase the temperature, helping the environment by cutting CO2.
• Eliminate draughts and cold spots
Not only will double glazing help you reduce bills due to improved energy efficiency, but you’ll also create a more comfortable environment. The replacement units will eliminate any draughts and cold spots in the property and ensure you’re able to better relax in your home.
• Improve sound insulation
Do you live in a noisy neighbourhood? If so, you’ll love the sound insulation double glazing brings to the table. In the same way double glazing keeps heat inside, it also prevents sound from entering. This means you won’t be disturbed by school children walking home, dogs barking or car doors slamming shut.
• Limit condensation build-up
Condensation is a serious problem in many homes, but unfortunately it seems an issue people simply accept as standard. Condensation is caused from excessive moisture in the air settling on the cold panes of your windows. If your home isn’t ventilated sufficiently, it can cause mould and mildew, even damaging your walls or curtains. Moisture build-up could be from showers, clothes drying and even breathing.
Replacing Windows with Triple Glazing
In recent times there has been growing interest in triple glazing. Although it has not been picked up significantly around the UK thus far, the level of sales certainly warrants the continued production of these efficient window units.
Effectively, triple glazing takes the efficient qualities of double glazing and builds upon these. Rather than having just two panes of glass, triple glazing instead has three. An efficient gas spacer – again, usually Argon, separates each pane.
As we know, double glazing offers a vast improvement to single glazed units, and triple glazing works off the same principal. The more panes of glass the better. But is this the reality?
Calculating the U Value
The U Value of windows has been mentioned previously and it’s here you can discover if triple glazing holds the key to furthering energy efficiency in your home. The lower the U Value, the more efficient your glazing will be.
The estimated U Value of windows is given below:
- Single glazing: 5
- Old double glazing: 3
- Modern double glazing: 1.6
- Modern triple glazing: 0.8
Is Triple Glazing Worthwhile?
Triple glazing is already the standard window replacement for many countries around the world, notably Scandinavia. As you can see, the U Value is significantly better than double glazed windows, albeit a little more expensive. That’s exactly why it’s chosen in colder climates as a way to combat heat loss in the home.
The payback time for triple glazing is on the same levels of double glazing too, so if you can afford the upgraded windows, it may be worth the investment. As such, all other benefits will be heightened with triple glazing, including environmental benefits, sound insulation and condensation reduction.