建筑墙体表面的太阳直射辐射投影及辐射强度随时间发生很大变化，该变化在已有的动态热过程算法框架内很难直接计算。根据建筑传热模型特点和计算机图形学原理，构建了动态热过程的建筑几何模型，该模型将建筑空间抽象为由矢量平面围成的空间区域的集合；提出了建筑几何模型的核心计算方法，即三维空间内直线与表面的矢量运算。该建筑几何模型能解决建筑动态热过程中直接计算建筑墙体表面之间的太阳直射辐射换热和太阳直射辐射投影等问题，并对空气流通、楼房之间的相互遮阳和光污染等问题的研究也具有实际意义。

The projection of sun direct radiation and the solar radiation intensity gained on wall vary with time; the variation can't be calculated directly in present algorithmic framework of dynamic thermal process in buildings. According to the feature of building thermal process model and the theory of computer graphics, a new geometrical model for analysis of building thermal process is advanced in the thesis. Building in the model is simplified into an aggregation of space regions, which are composed of vector planes. Core arithmetic method for the geometric model is presented, which is vector calculation for straight-lines and planes in three-dimensional space. The geometric model can help to realize the direct calculations of solar direct radiant heat exchanges between walls, and the projection of solar direct radiation; it also has practical value on air flow, mutually shading between buildings, light pollution problems and so on.