ᐅ New Construction – Is Insulation Worthwhile? Experiences?

Good day, esteemed experts,

We are currently building our single-family house. It is being constructed using solid masonry (T9 unfilled 36.5), with a living area of approximately 290sqm (3120 sq ft) spread over three floors.
The roof will be insulated with about 24cm (9.5 inches) internally and 5cm (2 inches) externally.
We will heat the house using a geothermal heat pump (underfloor heating). Additionally, the house will be equipped with a controlled mechanical ventilation system. It should also be mentioned that we will have a fireplace (mainly for the ambiance). A photovoltaic system will be installed on the roof, potentially covering the entire surface area. The question now is whether it makes sense to additionally insulate the exterior walls (ETICS / external wall insulation system)?

We are not building to KfW standards…

Please do not be too harsh in your judgment ;-)

I could not find an answer to my question through the search function.

Our goal is to achieve good insulation in summer and, of course, to minimize heating costs.

Thank you for your kind exchange.

Best regards

Your masonry is designed as a monolithic wall, meaning the masonry itself also serves the purpose of thermal insulation. However, it would be pointless to apply an external thermal insulation composite system (ETICS) on top of it. If you want better insulation, use a higher quality or thicker insulating block, or change the wall construction entirely.

The house is already halfway built… Therefore, unfortunately, I cannot use thicker or insulated blocks. Is this sufficient to cover the "current" status or to meet the technical standards?

If you are still considering the wall construction, the building process hasn’t started yet. May I ask what budget you have planned for this massive structure?

Edit: Well, if the house is already built, it doesn’t really matter... You don’t change that in the middle of construction.
Still, I’m curious about the budget.

The house is already halfway built.
Therefore, the question arises afterward whether adding extra insulation on the outside would make sense...

For the budget, just the house is about 500,000