A Rated French doors & A Rated obscure glass

[DHFrames]

Guys

Need your views on an energy rating issue I have.
As far a I'm aware obscure glass can't reach an 'A Rating' due to the iron coating, the maximum is a 'B Rating'. Correct ????!!!!!
Also the overall u value (not the center pane u value) on upvc French or patio doors also can't reach 'A Rating'. Trying to explain WER, u values etc to a customer is not easy and another company are claiming all their windows and doors with or without obscure glass is 'A Rated' which I think is ballsheet!!
Views please

Dan

 

[Gazman16]

Not sure about only B rated with obscure glass, When I buy obscure windows they still come with an A rated sticker and Ive never entered a B rated code for them while putting them through Fensa.
I'm fairly confident that fitting trickle vents in a window strip away any rating they would get though.

As for doors I believe you are correct although I cant find any documentation to link for you. I just had a quick flip through the Doorstop trade website and only one of their unglazed doors reach an A rating.

When A rated first came out I kept getting complaints about the external condensation so now I tend to recommend B rated windows to my customers down here in Somerset. I print this out with my quotes and let the customer decide (think I got most of it from either Pilkington or Planitherm website):

A,B or C rated windows?
What is the average saving to householder between A, B & C rated windows in terms of energy and cost savings?
A, B and C rated windows are all much more energy efficient than standard windows. That said, there are differences in performance of energy efficient windows with A B and C ratings;
• Changing existing single-glazed, timber windows to Band C windows in a semi detached, gas fuelled house would be expected to save £4350 in heating costs and 11 tonnes CO2 over 20 years.
• If the new windows are instead B-rated then the savings increase to £4650 and 11.5 tonnes CO2 .
• And, if the new windows are instead A-rated then the savings increase to nearly £5000 and over 12 tonnes CO2 .
The above shows that achievement of the level C displays significant savings over existing windows with higher ratings of B and A delivering further smaller incremental savings above C.

The only physical difference between our A & B rated windows is the spacer bar (the bar that separates the 2 pieces of glass in a double glazed unit).
B rated units have a metal spacer bar.
A rated units have a foam/plastic spacer bar.
Using the above example fitting A rated rather than B rated would save about £350 on heating bills over 20 years which is a £17.50 saving per year.
We recommend B rated windows due to the increased risk of external condensation that we have noticed locally with A rated windows. Although it is possible to get it on both B and C rated windows too it seems to be much more likely to happen with A rated. When it does happen it will clear faster on B rated windows as a little more heat escapes to the outer pane.
It is not a major problem but if you Google external condensation you will find many people complaining that they are unable to see out of their new windows mainly in the mornings during cold weather.

 

[DHFrames]

I don't get how companies can say they sell/install A Rated windows??!! It's not the window that makes up the energy rating it's the glass. Yes there's helping options regarding small outer frame, thermal inserts etc but if you got a 1200x1200 fix pane window with no glass there's no efficiency, as soon as you put the glass in a u value is then established. If my customer wants that fix pane window to be A Rated the window gets put through the computer it then tells you what glass is required to get that overall window rating up to the required u value!
Obscure glass can only achieve a B Rating... I'm sure!! I think I'm sure??!!
Glass companies fail to mention this, probably has minimal effect on efficiency but still!! As you agree doors can only reach a B Rating yet finding info online regarding this is hard to find as companies don't want to weaken their sales potential!!

Totally agree on the trickle vents along with the doorstop a rated slab, I'm sure there's a couple of A Rated Ali doors out there as well??!!

Anyway, confirmed clarification awaits!!

 

[Gazman16]

Im not convinced on the obscure units, They still have the coating on the clear pane (side 2) and warm edge spacers and argon fill.
Just to confuse matters I always fit the clear pane to the outside lol.

I think the main reason for not having ratings on doors is the number of possible combinations and the cost of testing them all. Think of all the door panel styles on the market and combine that with the different foil, reinforcement and thickness options, Then you have things like door frame threshold options. If they had to test every possible combination to give them all ratings it would cost a fortune.

I think most of the sales guys just gloss over the facts or just bare faced lie due to lack of knowledge and also not wanting to confuse the customers.