Problems caused by high energy consumption as well as issues regarding poor ventilation, inadequate climate control or a general lack of comfort can often be traced back to errors in initial design. Extremely complex relationships must be taken into consideration. This is particularly true when calculating thermal loads, the influence of seasonal fluctuations or the impact of solar radiation and building perfusion. intecplan was one of the first engineering firms to utilize computer generated simulations during planning phases in order to analyze these interactions. Using the applications which we have refined, we are able to make early, accurate statements concerning dynamic interactions relating to climate, solar radiation, temperature or humidity and energy consumption.