ᐅ Replacement of Ytong Lambda 0.09 with Ytong Lambda 0.08

Hello,
we are building a KFW55 house. The standard includes a Ytong block with a thermal conductivity (lambda) of 0.09.
For an additional cost of about 1400€ we could get a block with a better thermal conductivity of 0.08.
Is it worth upgrading?

Regards
body

No. Additional cost of 1400,-. Heating cost savings of 10,- per year, maybe 15,-. Don't do it.

Thank you. We will leave it as is.

Regards
body

Nordlys schrieb:
No. Additional cost is 1,400. Heating cost savings are 10 per year or maybe 15. Forget it.

Wait a moment. The response is a bit rushed.
How confident are you, @body123, in achieving a Lambda value of 0.09 with the KfW55 brick?

I myself cannot reach KfW55 without a Lambda of 0.08. Is your 9 (0.09) brick sufficient? What did the energy consultant's calculation say?

It can be worthwhile if the wall stone can be made thinner. This creates additional living space, which can be factored into the cost. A slimmer wall construction might also be preferred for aesthetic reasons. However, purely in terms of heating costs, this wouldn't make sense.

Visually, thicker masonry always looks better in my opinion. Ideally with angled reveals 🙂 Monastery style, yeah!