Steps and challenges to design a sustainable building in tropical environment

One of the projects of our foundation is to share information on sustainable construction in the Tropics and to build a model house that can inspire all builders in Bali and elsewhere in the world under the same latitude.

The first point, totally cultural, is to get rid of this symbol of modernity that is air conditioning. Air conditioners not only represent 10% of global electricity consumption but they release refrigerants which are powerful greenhouse gases. We build without thinking about the orientation of the building, its envelope, its openings because we know that with air conditioning, we will maintain thermal comfort in the building. But in doing so, we all know that our ecological footprint condemns future generations, we now speak of temporal colonization because we steal the resources of our descendants.

In 2023, we continue in Bali to build concrete bunkers painted in black with large windows exposed to the sun that run the air conditioners. And yet, concrete not only stores heat but has a high carbon footprint during its manufacture. Black paint on a tropical building is an environmental aberration because it traps heat. And finally large unshaded bays also contribute to the storage of heat and do not allow air to circulate. And in Indonesia, where more than 60% of electricity is produced with coal, the more electricity we use, the more greenhouse gases we emit and the more we contribute to social and environmental problems.

The new credo is porosity, an old principle that urgently needs to be brought up to date, the circulation of air in buildings.

The second point to keep in mind is the word bioclimatic. Take into account sun exposure (in Bali, orient buildings east-west and completely reduce openings to the north) and wind orientation (in particular the wind) and assess the air flows in the building (calculation of the air flows linked to the climate motors, calculations on some air speed zones).

The third point is the Negawatt approach. Applied to a various energy-consuming equipment, this strategy provides a rigorous methodology to recover as much as possible:

Passive or active recovery of climatic elements to meet energy needs.
Sobriety in the operation of the installations or in the appropriation of the operation by the users.
The efficiency and optimization of the envelope components and the necessary equipment for the operation of the building.

The fourth point is the overall cost. The initial investment, decisive criterion for the client, must be put into perspective and put into perspective on the life of the building by integrating the costs related to operation, maintenance, upkeep and exploitation. This approach can value some over-investment by saving building lifetime.

The fifth point is the carbon footprint the energy content of the building (embodied energy) for its construction represents the equivalent of the energy consumption of several decades of operation of the establishment. Similarly, the choice of location for a project can be decisive if the environmental cost of transporting people is considered.

The analysis of the site naturally includes different criteria:

The physical environment topography, soil type, hydrology, natural disasters (landslides, earthquakes, etc.) and soil pollution
The climate: exposure to the sun and shade (neighboring buildings or existing vegetation), prevailing winds
The shipyard: riparian, waste recovery
Biodiversity: existing fauna and flora
Proximity nuisances: acoustic, visual, odor, electromagnetic field – relay antenna or high voltage line)
Local resources: sustainable energy, local materials, local facilities and services

Once this site analysis has been carried out, the two main guidelines for drawing the construction plan of the building are the thermal and aerolic zoning consistency, in other words how to protect yourself well from the sun and how to best circulate the air to cool the building either with the prevailing winds or by pressure difference.

Here are the general principles of bioclimatic architecture adapted to Bali (8 Degrees South):

Natural ventilation (separated building mass, porous opening, high ceiling)
Solar shading (movable shading, building self-shading, double roof)
Day light (light tube, light shelf, sky light)
Micro climate adjustment (pond, landscape)
Roof insulation (white roof)
Heat capacity (high mass in day time, lightweight in night time)
Nocturnal radiation (high emissivity material)
Stack ventilation (chimney effect)
Evaporative cooling (with caution)
Orientation (East-West, blind on the North)
Stilt construction to promote air circulation.

Concerning the building envelope, here are the main points to consider:

Limitation of the direct light
Optimize natural ventilation
Controlling air permeability
Thermal insulation on the exposed wall and the roof

Finally, of course, a bio-climatic house takes into account the rainwater harvest and also produces its own energy:

Collect rainwater and store it in tanks. Big problem of water resources in Bali, contamination of groundwater.
Install solar panels because it gives us a guaranteed price for electricity for 20 years (their lifespan)

Science without conscience is only ruin of the soul and the immoderate use of concrete and air conditioners in the Tropics is an ecological aberration. It is time to look for viable alternatives for construction, to draw on the past while adapting low-tech techniques with contemporary designs, that’s the responsibility of every architect, every builder and every client and it is the fight of the Greengreat Program and the Ocean Gardener Foundation.

Eloy LARCENA
Construction Engineer

Sources :

International Shading design strategies within the Tropical Modernist Nigeria: Lessons for Nigerian Designers, in ijird.com, June 2015

Manuel de bonnes pratiques architecturales. Eco-construction et efficience énergétique dans les Bâtiments, CTB Sénégal, June 2017

Conception Architecturale Durable en Milieu Tropical, ONU Habitat, Institut de la Francophonie pour le Développement Durable, 2015

Tropical Sustainable Architecture, Social & Environmental Dimensions, Joo_Haw Bay & Boon-Lay Ong, Architectural Press, 2006