Athermic glass or plastic windows which is best ?

many thanks for all your valuable info.

I have also looked on the AS owners forum and most people seem very pleased with the athermic glass - except possibly in the coldest winter weather.

I'm not in a rush to buy so will look into this further.

Winter is the only uncertainity so I shall also look into if it's possible to find a hire an AutoSleeper in the winter to see how it performs.

many thanks all

If the claims made by Auto Sleepers are to be believed their so-called athermic glass must have different properties to what one normally understands to be athermic glass which never results in an improvement in interior comfort in cold weather conditions. It would therefore be interesting to know more about the construction of their design.

We're obviously talking about two different things here.

ps: It's difficult to know what to make of Auto Sleepers' claim because they don't say how much worse the plastic double glazing performs. They only say how good the athermic glass is. Therefore it's not possible to judge whether there is any actual improvement.

I think AS are saying they have improved van insulation generally and the glass is only part of the consideration. It would be more true to say that glass comes in all types of forms and newer types of glass provide a variety of properties in different situations including improved insulation. AS have used athermic glass to good effect, retaining or reflecting heat (it does work , we have experienced it) but one of the main advantages is the actual window design which also improves security.

As mentioned A/S have chosen to construct their base vehicle on a mini-bus chassis as opposed to a panel van. So the base vehicle comes with what I understand to be fixed tinted windows bonded into the sides of the vehicle. These its seems are described as "athermal" which I translate as "not thermal" but I don't understand what the "not" is. Does it mean that the windows do not conduct heat IN or  does it mean that they do not conduct heat OUT or does it mean that the windows have no thermal effect.  Since the windows are single glazed it may be that they have no more thermal efficiency than a windscreen (which is one of the big areas of heat loss in a van). A/S refer to Grade 3 insulation however in this context the standard in not a measure of insulation but a "classification for heating and thermal insulation i.e two things taken together " measured by performance. Essentially so long as the van can reach the prescribed temperature of +20 within four hours. It meets the standard. So in theory at least the insulation (of which the windows are a significant component) may be very poor but the heating system very good. Good enough at least to bring the van up to and keep it at 20c within four hours. This seems a very low standard and realistically who could wait for four hours for a van to get warm.

To put that in context in June we were at Kiruna in Northern Sweden where the daytime temperatures were around 0c and at night dropping to -10c. With no heating overnight our vans insulation was sufficient to sleep comfortingly without heating and a few minutes of diesel heating brought the interior up to a sufficient 16c which could be maintained by a 1kw fan heater intermittently. 

I have no direct experience of so called athermal windows and clearly some people like them. For some good thermal performance in unimportant and for some the external appearance is pleasing.

I suspect the choice of this window method is driven by cost saving as the cutting out (accurately) of window apertures and the fitting and trimming of fitted windows is skilled and time consuming.  

Personally I find the uniformity of appearance across a model range and the dark appearance aesthetically displeasing. I also question the degree of insulation which this type of windows provide. 

I doubt that the glass has much effect in reducing conductive heat transfer but radiated heat it will

Yes but presumably the main source of radiated heat would be the sun i.e. reducing heat coming in. This may be of significant value particularly for hot weather of sunny places but presumably there is little radiated heat going out . 

Of course I tend to think of heat insulation as being about heat retention but there is a role for the "non heating" affect as well or have I got this all wrong ??

All I know is that it suits us. What’s more the glass windows don’t leak and don’t rely on a caravan builder using the right sealant around them. 

I don’t much care what it looks like or the technicalities of the glass. It works and we're happy.

I have an Autotrail V line 600 of 2014 vintage, and we love it !

However, it is on its 4th set of Polyplastic double glazed tinted opening windows !  The previous ones have all gone seriously concave in the double glazed section after being in the sun for a few hours.Firstly the double glazed area goes 'foggy' then the exterior plastic seems to soften and draw inwards, At first i thought they would 'reform' as the cooled down....but they never did, leaving them badly deformed, the worst part was as the center was drawn in to a dish, the corners pulled out and flapped dangerously into the slipstream...threatening to rip the window out at any speed above 50mph.

The latest windows have untinted centers, and seem to be ok. But we have lost the privacy of tinted windows and has changed the look of the van badly. So much so we are considering replacing the opening windows with fixed solid glass windows as are fitted on Autosleeper PVCs.

Several other early V line owners have gone down this route, at their own expense, and are very happy with the results.

Autotrail stopped making the 'Classic' 6XX series of vans with double floors and raised fibreglass roofs in 2016. Saying they were too expensive to produce !  Probably the warranty costs of all those 'Wonky Windows' ?  

In answer to the op's original question : my advice would be to get an Autosleeper PVC,  our choice would be a Kemerton XL.

Good luck in your choice.