Thermal and acoustical performance of building systems: study of tools that assist NBR15,575/2013 Brazilian building standard compliance assessment

ABSTRACT The Brazilian performance building code (NBR 15,575) addresses some requirements to assess the residential sector. However, setting a construction system option that meets this code has proven to be challenging. This study aims to evaluate the thermal and the acoustic performance of a social housing envelope, situated in Contagem-MG (Brazil), according to the minimal limits set by NBR 15,575. Structural masonry of ceramic blocks was selected for vertical sealing as well as concrete (floor-pavement) slab and ceramic tile, for horizontal closure. The NBR 15,575 simplified method was carried out for thermal analyzes whereas acoustic evaluation applied standard calculation and simulation method using Projetus software. Results indicated that the external walls need a thermal capacity improvement and the living room inner wall, which splits both unit apartments, need to increase its sound reduction index (Rw). Therefore, 2.5cm of plaster in both sides of wall should solve those problems. After this change proposition, the thermal and acoustic minimal performance standard were achieved. A small variation could be notice between calculation (Rw) and simulation sound insulation results (DnT,w and D2m,nT,w). Projetus is perfectly suitable for preliminary studies. As a conclusion, thermal and acoustic building system assessment in an early stage show to be relevant to foster its compliances adjustments as occurred e.g. in this study. Otherwise, major interventions may be necessary either at building site or after construction ends.

摘要 巴西建筑性能规范（NBR 15,575）针对住宅建筑领域提出了若干评估要求。然而，筛选符合该规范的建筑系统方案却颇具挑战。本研究旨在针对巴西米纳斯吉拉斯州孔塔任市（Contagem-MG）的一处社会住宅围护结构，依据NBR 15,575规定的最低限值，评估其热工与声学性能。研究选用陶瓷砌块承重砌体作为竖向围护结构，混凝土（楼面）板与陶瓷地砖作为水平围护构件。热工分析采用NBR 15,575简化计算方法，声学评估则借助Projetus软件，采用标准计算与仿真结合的方法开展。结果显示，外墙需提升热工蓄热性能，而分隔两套住宅单元的客厅内墙需提高其隔声量（Rw）。因此，在墙体两侧各涂抹2.5cm厚的抹灰层即可解决上述问题。该调整方案实施后，热工与声学性能均达到了最低标准限值。计算得到的隔声量（Rw）与仿真得到的隔声结果（DnT,w及D2m,nT,w）之间仅存在微小差异。Projetus软件完全适用于前期研究工作。综上，在项目早期阶段开展建筑系统热工与声学性能评估，有助于像本研究一样及时调整方案以满足规范要求；反之，则可能需要在施工现场或竣工后进行大规模整改。