We see that under the economic alternative, the investment on constructing a low standard building is significantly smaller, involving an additional cost of 0.11% (large building,medium standard) to 1.33% (small building, medium standard).Furthermore, the difference in cost stems mostly from the lower investment on energy saving, which required no extra cost under economic optimization. These data show that energy efficient design has a major effect on construction costs. The economic optimization of other chapters only had minor effects.