Discussion of the limits of the thermal properties of building envelopes according to Brazilian thermal performance standards

Abstract One of the purposes of thermal performance standards for buildings is to evaluate the building envelope, identifying those building that are appropriate and can guarantee a minimum performance and hence the thermal comfort of users. In Brazil, there are currently two standards that regulate the thermal performance of residential buildings: NBR 15220 (2005) and NBR 15575 (2013). Some studies point out inconsistencies in these standards, especially with regard to the limit values for the thermo-physical characteristics of walls and roofs. The aim of this paper is to evaluate the thermal comfort of a multifamily residential building, adopting Mahoney's limit values, comparing these results with those obtained through the normative values for each of Brazil's bioclimatic zones. The analysis was performed through simulations using EnergyPlus© during one year in 24 Brazilian cities. The results point to the need to review especially the values adopted for the thermal capacity of walls and the thermal transmittance and solar absorptance of envelopes in NBR 15220 (2005), as well as the need to establish values for the thermal capacity of walls and the thermal capacity and solar absorptance of envelopes in the case of NBR 15575.

摘要 建筑热性能标准的核心目标之一是对建筑围护结构（building envelope）开展性能评估，甄别出符合最低热性能要求、可保障使用者热舒适的建筑。当前巴西共有两部规范住宅建筑热性能的标准：NBR 15220（2005）与NBR 15575（2013）。已有多项研究指出这两部标准存在不一致之处，尤其针对墙体与屋面的热物理特性限值条款。本研究以马奥尼限值为基准，针对某一多户住宅建筑的热舒适性能展开评估，并将所得结果与基于巴西各生物气候区规范限值计算得到的结果进行对比。本次分析采用EnergyPlus©能耗模拟软件，对巴西24座城市开展了为期一年的模拟计算。研究结果显示，亟需修订NBR 15220（2005）中墙体热容量、围护结构传热系数与太阳吸收率的取值标准；同时也需为NBR 15575（2013）补充墙体热容量、围护结构热容量与太阳吸收率的相关限值规定。