This paper addresses the problem of modeling complex behaviors, especially social human behaviors, in multi-agent based simulations. Incremental approaches, - a first and simple model that is enhanced step by step - are a common way to deal with complexity. We argue that incremental modeling is a valuable methodology, but needs to be assisted both to quicken the modeling iterations and to enable a smooth and intuitive increase in complexity. Our proposal is based on a software environment that enables easy evaluation, comparison and manipulation of simulations, and situated modeling. Situated modeling is a procedure that allows the modeler to adjust the behavior of an agent in a specific context from a simulation. Those adjustments enrich little by little the agent decision mechanism with new situations. Our incremental modeling environment and preliminary results in situated modeling are presented in the context of the SMACH platform. This research project aims to study the use of electrical appliances by the inhabitants of an intelligent house.