For houses with low operational energy demand, the relative importance of the other life cycle phases is larger than in standard buildings. For such buildings the choice of material becomes more important. Studies have shown that buildings constructed with wood require less energy during the lifecycle, compared to other materials. We have compared the primary energy use for production and operation of a wood building and a concrete building, traditionally constructed, and a low-energy concrete building. We also evaluate the effects of energy efficiency measures applied to the wood building and of different energy supply systems. We show the importance of both material choice and energy supply systems when optimizing life-cycle energy use of buildings.