How to get windows U-value certified

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sibsssidor

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Hi - I'm thinking of fitting a heat pump and just got my BER rating re-done since it was done in 2019 and did not report the HLI, so trying to find out if I'm eligible for grants or not. The BER guys apparently put a default (and pretty bad) U-value on my windows, since I have no written certification of the type of glass and window (double glazed fitted in 2007). They told me I have to get some sort of document from the company that fitted the windows. Luckily the company is still there, but after two emails and a couple of phone calls I did not get any help.
Is there somebody around who can certify the window U-value and write it on a piece of paper for the BER crew (possibly without costing me an arm and a leg)? Any help/advice appreciated.
 
sibsssidor said:
They told me I have to get some sort of document from the company that fitted the windows. Luckily the company is still there, but after two emails and a couple of phone calls I did not get any help.
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For my BER cert the certifier insisted on original quotes and invoices from the company with the U-value specified. Luckily I'd saved them.

I've no idea if anyone can retro-certify a U-value if the manufacturer or supplier won't.
 
@NoRegretsCoyote tx! what kinda bothers me is that the make and model of the window is stamped inside the window itself (Vistatherm, EN 1279 Insulating Glass Units), together with the manufacturing date. The BER guys completely ignored that. I'll try with the manufacturer... :-(
 
I tried to get U value for rationel windows installed in 2007, but at that time there was no requirement to quote them, so on invoices and windows has descriptions but nothing stating the U value.
I spoke to them but as they were never rated then couldn't provide. The U value could vary window by window,
 
IIRC, it depends on glass and frame. Did the marking on window cover complete unit or just the glass?
 
sibsssidor said:
what kinda bothers me is that the make and model of the window is stamped inside the window itself (Vistatherm, EN 1279 Insulating Glass Units), together with the manufacturing date.
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As above, that's not a 'make and model' of the full construction, it's a manufacturer name and a reference to the European standard that all insulated glass panels had to meet. All glass units from the best to the worst available had to meet that standard. The frames those units were put into varied significantly in energy performance too, and it is the performance of the package that counts.

The only sure way to know the ratings is to have the manufacturer or supplier reference their records of what was produced and see if they have energy specifications that meet today's requirements. There's no requirement for them to retain such records for so long, so it is unlikely you will get them. After 13 years, the performance of the windows will have degraded.

What BER level did you achieve in the recent assessment?

Possibly more important questions, what makes you want to go with a heat pump? What's your current heat source, and how much energy are you using to heat the home?
 
Leo said:
As above, that's not a 'make and model' of the full construction, it's a manufacturer name and a reference to the European standard that all insulated glass panels had to meet. All glass units from the best to the worst available had to meet that standard. The frames those units were put into varied significantly in energy performance too, and it is the performance of the package that counts.

The only sure way to know the ratings is to have the manufacturer or supplier reference their records of what was produced and see if they have energy specifications that meet today's requirements. There's no requirement for them to retain such records for so long, so it is unlikely you will get them. After 13 years, the performance of the windows will have degraded.

What BER level did you achieve in the recent assessment?

Possibly more important questions, what makes you want to go with a heat pump? What's your current heat source, and how much energy are you using to heat the home?
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@Leo tx Leo! I thought Vistatherm was the producer of the glass, but maybe they don't make the frames? I see the story is way more complicated than I thought. Don't see a way out of this without the supplier stepping in, I agree after 13 years they may not be able to help me. The house is rated B3 and has oil heating. I burn more or less 600 liters of oil per year. I've done external insulation, attic, fitted solar panels and heat recycling vents. The reason for looking at a heat pump is simply decarbonizing.
 
sibsssidor said:
The house is rated B3 and has oil heating. I burn more or less 600 liters of oil per year. I've done external insulation, attic, fitted solar panels and heat recycling vents. The reason for looking at a heat pump is simply decarbonizing.
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What's the approx floor area of the house?
 
sibsssidor said:
@Leo tx Leo! I thought Vistatherm was the producer of the glass, but maybe they don't make the frames? I see the story is way more complicated than I thought.
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Yeah, they produce a range of glass units with different performance levels, someone else adds a frame and frames also have different performance ratings, and both components factor into the overall efficiency score. So without the supplier confirming, you're unlikely to get anything better than the guided estimate.

sibsssidor said:
The house is rated B3 and has oil heating.
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So I think you shouldn't need to prove better performance to qualify for the heat pump grant, isn't that available for C1 and above?
 
sibsssidor said:
No idea. They must have some default value for double glazed windows? :-|
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Yes there's default values for everything they can't verify with invoices. For example, there's different default values for single glazed, double, triple etc, along with different defaults for the u value of the house walls based on the year it was built and the type of construction (different building regs depending on the year).

Up until recently you could download the DEAP software from the SEAI that the assessors use to generate the BER. When I got a BER 3 or 4 years ago I asked the assessor to send on the xml file exported from that, then I was able to see exactly what values he had set for everything using the DEAP program. It was eye opening to see the amount of things he got wrong that negatively affected the final BER rating.

It looks like there's a new online version of DEAP now - https://www.seai.ie/home-energy/building-energy-rating-ber/support-for-ber-assessors/software/deap/ Looks like it's open for anyone to use, though I haven't tried it, so you may still be able to get some similar file from the assessor to upload onto that.
 
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If the heat pump makes sense (not saying it does) with the assumptions the BER assesor has made, and you think your U-value would be over and above the BER assessor's estimate / assessment - then don't worry about, the heat pump will still make sense
 
Happy ending - the supplier (probably out of exhaustion... :) ) came back to me and provided the data. Got the grants, heat pump is up and running one year, and after an initial phase of tuning works very well. Thanks everybody for the help on this thread!
 
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