variavel0=Nathan Mendes - nmendes@ccet.pucpr.br Pontifícia Universidade Católica do Paraná Gerson Henrique Santos - ghsantos@ig.com.br Pontifícia Universidade Católica do Paraná Abstract. In this work, it was analyzed and compared, in terms of room air temperature and relative humidity, different numerical methods for integration of the air-domain governing equations in time once non-steady building simulations are carried out for periods as long as one year. A lumped approach to predict the room air temperature and relative humidity is used and a one-dimensional multi-layer model in finite differences for the ground and building envelope is employed. The external weather was simplified by the use of sine functions for temperature, relative humidity and solar radiation. To evaluate the building performance with thermal parameters, we have written a code which includes air infiltration, conduction loads, internal gains of people, lights and equipment and short and long wave radiation. Keywords. building simulation, numerical methods.