The Facts
Fact 1. How It Works
Basically to get rid of the moisture from the inside of a double glazed units or to prevent the unit from fogging the unit needs to be re-engineered, the transformation from a hermetically sealed unit into a pressure equalised unit is not that difficult.
We refer to the unit as hermetically sealed (gas tight) however if you are reading this it is likely that you have moisture in your units, this means the seal has failed and the unit is no longer air tight, we call these units "Blown" and most people will simply replace the unit with another, the replacement solves the problem of moisture ingress that's for sure however it is only a short term fix and the problem will return when the new unit seal fails.
Re-engineering the failed unit solves the problem, is cheaper than replacing the unit, last longer than replacements and what's more is the most environmentally friendly option (most failed sealed units go straight to landfill).
The re-engineered unit has the same thermal performance as a standard air filled unit, air will escape from the unit when the temperature rises and air will be allowed to re-enter the unit when the temperature drops.
The additional features added to the original (Vent, Anti-Fog Coating & Sealer) unit work simultaneously to prevent any further damage to the unit, to prevent any further ingress of water into the vault and finally prevent the moisture in the air fogging on the glass.
The real question we should be asking is why do they not make units like this in the first place?
Fact 2. Affects on the units thermal performance.
Basically if the unit is air filled the re-engineering has no affect on the thermal performance of the unit, tests carried out and independently verified by a leading University in the UK compared a brand new unit with an identical pressure equalised unit and the thermal performance were the same.
If you replace the failed unit with a gas filled, warm edge, low thermal emissivity glass unit (A Rated) it will slightly outperform the re-engineered unit, however the saving made on lower heat loss over the next 5 - 10 years will never pay for the cost of upgrading the unit and what's more the unit will most likely need replacing again and again and again.
Fact 3. Safety Glass.
All units can be re-engineered and safety glass is no exception, there are basically two types of safety glass toughened and laminate.
Laminate Glass:
Laminate glass is basically two thin pieces of standard annealed glass with a safety film sandwiched between them, the re-engineering process is carried out in the same way as standard window annealed glass.
Toughened Glass:
Toughened glass is heat treated annealed glass, toughened glass can not be drilled therefore the re-engineering process is carried out through the side of the unit (spacer bar), different tools and equipment is needed to work on toughened units (included in advanced kit) and the unit will need to be removed from the frame to gain access to the units spacer bars.
Save Your Windows, Save Your Money, Save the Environment.