"Passive house" has become a sales pitch, so real numbers are worth having. Ours come from three houses we designed and followed for two years after the owners moved in.

The extra cost
Between 12% and 18% over a house built to minimum standards. The difference is in insulation thickness, triple glazing, heat-recovery ventilation and, most often underestimated, in careful workmanship at thermal bridges.

The payback
Heating bills dropped by 70-80%. At current energy prices, the extra investment is covered in nine to twelve years.

What the calculation misses
Steady thermal comfort, with no cold draughts by the windows. Filtered air, which matters a lot to allergy sufferers. And, on resale, an energy certificate that moves the price.

Where it goes wrong
The most frequent error is good insulation over careless work. A thermal bridge at the balcony slab cancels half the gain. This is why site supervision is not optional on these houses.