Nothing is forever.
I was reminded of this when I watched Mel Gibson’s Apocalypto recently. The film is about the decay and collapse of the Mayan civilisation in Central America. This collapse was caused by overpopulation coupled with the overuse of resources that led to internal political conflict and subsequent demise.
Closer to home we have the Khmer civilisation whose decline occurred for similar reasons. In each case, foreign invasions hastened the end of these civilisations and now all we have to remember them are beautiful abandoned ruins.
I would hate for anything like this to happen here, but we live in an age of climate change and the resources needed to sustain us are finite. In addition, we have a growing population wanting to consume more and more of these resources.
What We Build
Buildings play an enormous role in the use of our resources.
By providing us with shelter, buildings allow us to operate in a climate by protecting us against extremes of cold and heat. Before air-conditioning was invented, we used the building envelope to ameliorate extremes of climate. Once a luxury, air conditioning is now affordable and we have become used to living in buildings at a constant temperature. But we should not take this for granted. Even though the purchase price may be low, air-conditioning should still be regarded as a luxury.
There is a large environmental cost in supplying the energy to operate air-conditioning and that cost is borne by the country not just the community. Cooling a building’s internal air requires removing the heat and that heat is exhausted outside the building. The million or so air-conditioning condensers (these do the work of removing the heat) in Ho Chi Minh City pump heat into an already hot environment, making the outside air even hotter, which in turn drives a need for more air-conditioning.
This ever-increasing burden of supplying that energy may be relieved by simply requiring the building envelope to be a “first responder” in dealing with the climate and thus reducing the amount of energy required for air conditioning. By doing so, energy requirements are greatly reduced and the savings, when multiplied across the city, are enormous.
The materials that make up a building also play a large role in energy use in two ways. First, science tells us the ideal solution for humid tropical climates is to build lightweight but highly insulated buildings elevated from the ground to allow air to circulate underneath and through them. Heavy masonry structures retain heat making them harder to cool. As we don’t have a high diurnal temperature range(the difference between night and day temperatures), heat cannot be removed at night. The buildings stay hot.
Second, building materials may cause indirect damage to the environment through their composition. Some building materials contain toxic substances, such as joinery elements containing formaldehyde, epoxy resins, chlorides including PVC. The use of primary rainforest timber also poses environmental risks.
The lessons we have learnt from those failed civilisations is that the common thread was overpopulation and the overuse of natural resources leading to environmental degradation — hastening the process of decline.
Conserving our resources is critical for our survival. As buildings consume nearly 30% of our resources, they are a good place to start. Requiring buildings to include strategies and systems to minimise energy, and to use materials responsibly is important for the future of Ho Chi Minh City.