How can I build the contents seperated because too big memory consumption?

Hi, Friends,
I am building a house with static lights and static meshes. For better quality I set the content’s light map to 1024 and the building’s to 2048 resolution. But it seems the engine is crazy and consumes about 16GB memory. In that case it is not possible to build better quality with small memory. How should I do? Is it possible to build the content seperated? What’s the good solution to lower memory consumption?

Thanks,
Fei