Do you live on a main road? If not, sound insulation is not that dramatic. It gets more interesting with the interior walls. We are still building with sand-lime brick (175 sand-lime brick, 160 mineral wool, 115 clinker), but more because we also want interior walls made of sand-lime brick and imagine that the higher storage capacity of sand-lime brick brings something ;) The theoretical insulation advantage of aerated concrete amounts to about 700 kWh per year for us - so about €35 (brine-water heat pump with an annual performance factor of about 4.5) - with gas that would be about €50 (if the m³ still costs 70 cents)