That doesn't sound correct... My understanding was that only quite recent appliances allow a mix of greater than about 30%, and networks can't be operated with a high mix without big upgrades (for 100% hydrogen I believe you need all the compressors to be about three times bigger than a natural gas network, so even getting over 50% H2 with the existing infrastructure doesn't sound right).
All in all I'm convinced it's just not worth doing for residential when you look at the challenges and the terrible efficiency. Since the majority of appliances aren't 'hydrogen ready', it's better to just electrify.
I tried looking for my primary source on this, it was an interview with someone involved with the gas infrastructure here. They mentioned specifically that it was newer than in the UK (and I assume some other EU countries) and that's why it could handle the higher admix. They also have good numbers on the appliances that are in use, there's been grants for a large scale upgrade, all the boilers that have been installed under these programs are rated to 80% H2.
I've no doubt you're right there would have to be significant upgrades done somewhere, but it might not be as big an issue for Ireland and I suppose it depends on how cheap that green hydrogen is for us, but we have to get there first. We'll use it for something.
All in all I'm convinced it's just not worth doing for residential when you look at the challenges and the terrible efficiency. Since the majority of appliances aren't 'hydrogen ready', it's better to just electrify.