夏热冬冷地区绿色建筑外墙节能特性的LBM模拟及效益分析

针对夏热冬冷地区绿色建筑中外墙的典型保温方式和常见保温材料,采用多松弛时间格子玻尔兹曼方法建立瞬态共轭传热数值模型,分析间歇耗能条件下墙体的瞬态热传导过程,进而得出不同类型保温外墙的节能特性。在此基础上,发展保温墙体增量综合效益的计算方法,分析绿色建筑外墙的增量成本及其增量效益,进而建立外墙增量综合效益评价模型,获取保温外墙最优设计方案。研究数据表明,采取内保温方式的外墙在该地区具有最佳的节能特性,尽管采用不同保温方式和保温材料的外墙均具有一定的节能特性,然而,在其全生命周期内,使用外保温方式以及增量成本较高的保温材料的墙体的增量综合效益出现负值,因此,不适宜在工程实践中应用。此外,研究结果显示,尽管增加保温层厚度可以在一定程度上强化外墙的保温性能,然而,增加保温层厚度会产生额外的增量成本,因此,绿色建筑项目实践中应综合考虑墙体节能特性及其增量成本进而选取适宜的保温层厚度,从而实现其全生命周期内增量综合效益的最大化。

Numerical Study of the Energy Saving Characteristic of Green Building's Insulated External Walls in Hot Summer and Cold Winter Areas Using LBM and the Benefit Analysis

To investigate the green buidling''s typical insulated external walls with common insulating materials in hot summer and cold winter areas, a multiple-relaxation-time lattice Boltzmann method (MRT-LBM) was developed for solving the conjugate heat transfer problem. The transient heat transfer process in the wall was analyzed under an intermittent energy consumption condition, and the energy saving characteristics of different insulated external walls were studied. Based on this, a computational approach for the incremental comprehensive benefit of the insulated wall was developed to analyze its incremental cost and incremental benefit. Under this circumstance, an evaluation model for the incremental comprehensive benefit was constructed to obtain the optimum design of insultated external walls. The results indicate that the walls with interior insulating layer have the best energy saving characteristic in this specific region. The whole lifetime incremental comprehensive benefit of the walls with exterior insulating layer or using expensive insulating materials is negative even though they could still save energy during the energy consumption period. Due to this reason, the walls with exterior insulating layer and expensive insulating materials should not be used in the real engineering applications. In addition, it is found that the energy saving amount of insulated external walls increases with the increment of the insulating layer thickness. However, the increased insulating layer could generate extra incremental cost. Hence, the optimum insulating layer thickness of external walls should be determined with fully considering their energy saving characteristic and incremental cost to achive a maximum incremental comprehensive benefit during the whole lifetime.