Impact of Buildings on the Environment and the Way Forward
One of the principal needs essential for the human race to survive is subsistence, which relies on an unconditional availability of food and shelter. The services involved in the operation of ‘modern shelters’, i. e., residential and commercial buildings — lighting, heating in the winter, cooling in the summer, water heating, electronic entertainment, computing, refrigeration, and cooking — require a staggering amount of energy. The energy required for the operation of buildings in the U. S.   alone corresponds to 42 EJ (1 Exa- joule = 1018 Joule) or about 1 Giga-ton-oil-equivalent (1 toe = 41.87 GJ). This accounts for almost 40 percent of the total U. S. energy use. This amount is equivalent to the energy released by about 670,000 atomic bombs of the ‘Little Boy’ type dropped over Hiroshima on August 6, 1945, a bomb that exploded with an energy of about 15 kilotons of TNT (63 TJ).
In addition to the operational energy employed during use, buildings embody the energy used in the mining, extraction, harvesting, processing, manufacturing and transport of building materials as well as the energy used in the construction and decommissioning of buildings. This embodied energy, along with a building’s operational energy, constitutes the building’s life-cycle energy and carbon dioxide (CO2) emissions footprint.
Energy efficiency of buildings has been on the agenda of many governments during the past 20 years. However, in order to effectively shrink the ecological footprint of our buildings, we must seek ways to ‘decarbonize’ our energy sources, i. e., we have to shift from the burning of fossil fuels to energy sources that do not release additional CO2 to the atmosphere. Renewable energy sources, such as wind, hydro, tide and wave, geothermal, photovoltaic and thermal solar, biomass fuels, as well as synthetic fuels produced, for instance, by genetically modified algae or bacteria or by the Fischer-Tropsch process from existing atmospheric CO2 are likely to play an increasingly important role in the future energy mix6,7. However, this shift towards more benign and renewable energies does not imply that energy efficiency is off the agenda. On the contrary, we have to strengthen our efforts directed at making our buildings more energy efficient. Finally, we have to consider ways of de – materializing as well as rematerializing our buildings. Dematerialization is a
reduction in the bulk (mass) of hardware and the associated embodied energy used in the construction of buildings (“doing more with less”), while rematerialization is the reuse or recycling of building materials at the demolition stage. Both dematerialization and rematerialization recognize that there are finite limits to the amount of materials we can extract from our planet.
The amount of carbon dioxide emissions that construction can influence is substantial. A British report, published in autumn 2010, estimates that construction-related CO2 emissions account for almost 47 percent of total carbon dioxide emissions of the United Kingdom. The previously cited U. S. EPA report estimates that buildings in the United States contribute 38.9 percent of the nation’s total carbon dioxide emissions. Due to the energy inefficiency of the existing housing stock, CO2 emissions generated during use of buildings in the U. K. account for over 80 percent of total CO2 emissions. Previous life-cycle energy analyses have repeatedly found that the energy used in the operation and maintenance of buildings dwarf the energy embodied in building materials. For example, Cole and Kernan, in 1996, as well as Reepe and Blanchard , in 1998, found that the energy of operation was between 83 to 94 percent of the 50-year life cycle energy use. Even for new, highly efficient office buildings located in China, where currently considerably less energy is being consumed by the operation of buildings when compared to the U. S.A. or Western Europe, operational energy accounts for 56 percent of the total life cycle energy11.
Building construction and demolition are major contributors to the waste we generate. In a report issued in April 2009, the U. S. EPA estimates that 160 million tons of building-related construction and demolition (C&D) debris is generated in the U. S.A. annually, of which 8 percent is generated during new construction, 48 percent is demolition debris, and 44 percent is
renovation waste. An estimated 20 to 30 percent of building-related C&D debris is recovered for processing and recycling. The materials most frequently recovered and recycled were concrete, asphalt, metals, and wood.
Regardless of one’s personal opinion about the consequences of the above facts and statistics for the future of humanity, any rational thinker among us must appreciate the serious cost overhead associated with all this waste. In monetary terms, can the waste laden expenditures of the past continue to be expanded and sustained by humankind in the 21st Century?