极端干热气候乡土建筑防热模型构建和遮阳设计优化

A Thermal Shielding Model and Shading Optimization Design for Vernacular Buildings in Extreme Arid Climate Areas

我国干热气候主要分布在新疆南部,甘肃、青海和内蒙古西北部等边疆地带,在建筑热工设计分区中被划分为严寒、寒冷地区,城镇建筑节能主要强调冬季保温,亟须夏季防热设计指导。不同的是,当地乡土建筑采用遮阳策略综合调节室内外热环境,形成独特的建筑防热模式,亟待继承与发扬。为此以极端干热气候为例,首先,通过乡土建筑现状调查,归纳了街巷、庭院,以及建筑屋顶、墙体、窗口等遮阳对象,总结了葡萄晾房、阿以旺、高架棚、棚盖、檐廊、葡萄藤架、透空墙、花格窗等遮阳方式;其次,通过现场测试与数值模拟相结合的方法,采用EnergyPlus软件,建立典型乡土建筑防热模型并验证其有效性;再次,在此基础上运用正交试验法,以建筑室内外环境全年综合热舒适百分比为评价指标,提出四类遮阳对象的防热节能作用由大至小的排序:庭院遮阳、屋顶遮阳、墙体遮阳、窗口遮阳,给出其遮阳面积水平的最佳组合,即屋顶遮阳100%、墙体遮阳100%、窗口遮阳25%、地面遮阳100%;最后,结合现有可行的遮阳方式,建议重点选用屋顶葡萄晾房、高棚架两类综合遮阳方式,形成屋顶、庭院、墙体、窗口的全面遮阳,在条件允许的情况下,考虑到不同季节遮阳需求的差异,高架棚宜采用轻质构造或葡萄藤种植方式,便于在冬季拆除。

The arid climate of China is mainly distributed in the southern part of Xinjiang,Gansu,Qinghai and northwestern Inner Mongolia and other frontier areas.These areas are classified as severe cold and cold regions in building thermal design zoning,and the energy efficiency of urban buildings mainly emphasizes thermal isolation in winter,while the guidance of passive cooling design in summer is urgently needed.Differently,the local vernacular buildings show climate adaptability,and the shading strategies were used to adjust indoor and outdoor thermal environments,the formed unique passive cooling mode needs to be inherited and developed urgently.For the reason,the Turpan vernacular buildings in extreme arid climate were taken as an example,based on field investigation,the shading objects such as streets,courtyards,roofs,walls and windows,and the shading methods such as grape drying rooms,Ayiwang,elevated trellis,canopies,gable porches,grapevine shelves,permeable walls,and lattice windows were summarized.In addition,through the method of field tests and thermal simulations,a thermal shiledling model for Turpan vernacular buildings was established based on EnergyPlus and its effectiveness was verified.On the basis,the orthogonal test method was applied to evaluate the thermal energy-saving effects of four types of shading objects.The order of thermal shielding effect from large to small was courtyard shading,roof shading,wall shading and window shading,and the best combination of their shading area levels was obtained,i.e.,roof shading 100%,wall shading 100%,window shading 25%.Furthermore,according to the existing feasible shading types,the roof grape-drying room and software elevated trellis were recommended as the comprehensive shading for the roof,courtyard,wall and window.Taking the differences in shading needs in different seasons into account,the elevated trellis should apply light-weight construction or grapevine planting method,which was easy to remove in winter.