Designing Ecological Habitats - Gaia Education

84 Designing ecological Habitats
Earth-air cooling
at BCIL Collective
Bangalore.
shutter, frame, vertical and/ or horizontal shading
devices, louvers, light shelves, curtains and blinds.
The design of fenestrations and its integration
with the building form poses a huge challenge to
the designer. If optimally designed, they can provide
glare-free daylighting, natural ventilation and a
vital link to the external environment. If poorly
designed, they can cause visual and thermal discomfort
through glare and heat gain.
In their research paper on analyzing the effects
of design parameters on thermal performance of
buildings (in the context of composite climate),
Ar. Rajeev Garg and Ar. Rajesh Jain of the
Department of Architecture & Planning, Indian
Institute of Technology, Rourkee (JIIA, December
2007), have simulated the model of a single room
building. The base case is a building with four walls, no fenestrations and sunshades.
The solar heat gain in this model has been compared with other models
with similar dimensions but with additions of windows, sunshades, doors, etc.
Thermal simulations were carried out for composite climate on May
30 for all the models oriented North. As the indoor temperatures were
compared, it was found that the model with no fenestrations had the
minimum heat gain as compared to the other three models. Shading the walls
in addition to shading the openings considerably reduced heat gain, which
is directly proportional to the number of fenestrations. Thus, fenestrations
significantly contribute to solar heat gain and hence should be designed with
utmost discretion. Large openings on north and south facades are useful
as they can be shaded with horizontal devices, while smaller opening are
preferred on the east and west phases, since they require vertical shading.
Vernacular Architecture
Vernacular architecture provides the best examples of architectural elements
employed for thermal comfort. The use of thick walls in the Bungas of
Rajasthan provides a time-lag for heat transfer, their round form minimizing
heat gain per square meter of surface area. The different sizes and types of
courtyards throughout India – from Rajasthan, Gujarat and Maharashtra to
the Konkan belt up to Kerala – present a wide variation in courtyard design;
in addition to providing privacy and an open-to-sky space, they also let in
ample daylight and air circulation throughout the house. Hot and humid
zones from Kerala, Maharashtra and Sri Lanka witness the absence of walls
and the predominance of the roof as a design element. Different designs of
the belvedere can be witnessed as it makes use of the prevailing breeze and
the stack effect in coastal areas. In the hot arid regions, thick walls, compact,
usually round forms, and courtyards use principles of thermal storage, ideal
surface-to-volume ratio and radiative night cooling respectively.