A research was carried out to identify the hierarchical importance of key issues for passivhaus buildings in the tropical wet and dry climate of Bangalore, India. It discusses low-energy building concepts to meet the substantial need for high levels of comfort in this region. The threatening rise of temperature due to climate change has led to rising concerns in the past few years. The exploration of passivhaus principles is carried out to ensure comfortable stay indoors for people through passive alternatives rather than their complete dependency on artificial cooling.
The behaviour of the case study building is optimized through PHPP calculations to measure the changes of various key issues based on the climate data of 2015. The U-values of all elements of the building is improved by introducing insulation and air tightness layer externally to the existing structure. It is observed that shading, double-glazed windows and elimination of thermal bridges play a vital role to promote passive cooling techniques and reduce overheating, thus lowering the space cooling demand.
A crucial aspect for passivhaus buildings in tropical climates is to control humidity along with a balanced ventilation system. Supply of fresh air is introduced to by-pass pre-programmed temperature and humidity cut-off limits. When it exceeds this threshold, additional dehumidification and cooling units will be switched on automatically during certain months of the year. The efficiency of passivhaus design process for the tropical climate is enhanced by following the hierarchical order of key principles analyzed through this case study.
Some of the usual assumptions and standard design strategies used for decades in this region prove to be invalid with changing climatic conditions. Opening of windows for cross ventilation based on old beliefs increase the internal load due to high humidity and rising temperatures. Passivhaus reduces this load by using balanced ventilation system with minimum dependency on mechanical cooling.
Human experiences of thermal comfort depend on their most recent experience amongst other factors including clothing and activity at the time. Bangloreans among other Indians are acclimatized to feeling comfortable in temperatures higher than 27°C while adapting to temperatures in high thirties and forties in the past decade. Setting an increased threshold for overheating in accordance to the levels of acclimatization for the region is considered to design comfortable indoor environments for the tropical climates.
Essential requirements for human comfort, design recommendations for passivhaus buildings and the hierarchical importance of the key passivhaus principles will be presented for typical buildings in the tropical climate zone based on the case study.
This paper can be accessed here. We are seeking further research opportunities and funding for the extension of the concept into Indian soil.
Presented on 29th April, 2017