Almost everyone having new windows fitted is asked the same question: HR++ or triple glazing? The answer depends on your home, your plans and your budget. Here is a level-headed comparison.
The difference in short
HR++ glazing consists of two panes with an argon-filled cavity between them, plus an invisible metal coating that reflects heat back. The U-value, how much heat leaks through per square metre, is around 1.1 W/m²K. The lower, the better.
Triple glazing has three panes and two cavities. That brings you to 0.7 W/m²K or lower. So it is roughly a third better insulated, but also considerably heavier: reckon on about 30 kg per m² against 20 kg for HR++.
When do you choose HR++?
For most homes HR++ is the sensible choice. If you are coming from single or old double glazing, the jump to HR++ is by far the biggest. The step after that to triple delivers relatively much less. HR++ is also cheaper and fits any profile.
- Your home is otherwise normally insulated (cavity wall, roof)
- You want good value for money
- You are replacing single or dated double glazing
When is triple worth it?
Triple pays off when the rest of your home is well insulated too. In a draughty house with an uninsulated roof you will barely notice the difference, the heat simply escapes somewhere else. Beyond that, triple is interesting if:
- you live on a busy road or under a flight path; three panes damp sound noticeably better
- you are aiming for a high energy label or something close to net-zero
- you have a heat pump or are considering one, those work best at low temperatures and therefore with good insulation
- you have large areas of glass; that is where the difference in U-value weighs heaviest
The subsidy argument
There is another reason to take triple seriously: the subsidy difference is substantial. For HR++ you get € 25 per m² back, for triple in new frames € 111 per m²: and double that with a second insulation measure. On 20 m² of glass that quickly comes to € 1,700, which covers a good part of the extra cost.
Note the condition: that higher amount only applies if the frames are replaced as well. Triple in your old timber frames earns the HR++ rate. And is often a poor idea structurally anyway, because old frames were not built for that weight.
What else to consider
Triple glazing is heavier, so the profile and hardware have to be made for it. Our Ideal 7000 profile (85 mm, six chambers) is prepared for it as standard; in the Ideal 4000 profile (70 mm) triple fits within more limited sizes. For large opening sections we always advise looking at what makes sense together.
One more point: with triple glazing on a north elevation, condensation can form on the outside in the morning. That is not a fault but a sign that the glass insulates well, so little heat escapes that the outer pane cools below the dew point.
Curious what it would come to for you?
Request a no-obligation quote or book a free measuring visit. Our own surveyor comes round, takes the measurements and advises you on the spot, you are under no obligation.