Sustainable Development

A  number  of  solutions  have  been  suggested  and  some  successfully  implemented  in  the past in several countries to produce clean energy and to maintain sustainability.  These  solutions  include  building  more  nuclear  power  plants,  geothermal  power  and  heat, solar heating and cooling, wind power, modern forms of bioenergy, solar photovoltaics, advanced biomass gasification, biorefinery technologies, solar thermal power  stations,  hot-dry-rock  geothermal  power,  and  ocean  energy.  Development  of  alternative fuels such as biodiesel, bioalcohol (ethanol, butanol), chemically stored electricity  (batteries and fuel cells), hydrogen, nonfossil methane, nonfossil natural gas, vegetable  oil, and other biomass sources has also been attempted. Each one has its advantages  and drawbacks. In the following we shall discuss only a few of these suggestions and  will confine the discussion to sustainable construction and the role of concrete.

The building and construction sector generates substantial social and economic  benefits,  employing  over  111  million  people  worldwide  and  contributing  approximately 10% to the global gross domestic product.At the same time, the built environment contributes significantly to global raw materials use, energy use, solid waste  generation, and greenhouse gas emissions (Figure 1).

More  than  any  other  human  endeavor,  the  built  environment  has  direct,  complex, and long lasting impacts on the biosphere. Some 10% of the global economy is  devoted to construction and about one-half of world’s major resources are consumed  by construction and related industries. It is estimated that, in the United States, the  building  industry  involves  the  extraction  and  movement  of  6  billion  tons  of  basic  materials  annually  (representing  8%  of  US  GDP  and  40%  of  extracted  material2);  residential and commercial buildings together use one-third of all energy and two- thirds of all electricity consumed in the country. They also account for 47% of sulfur  dioxide emissions, 22% of nitrogen oxide emissions, and 10% of particulate emissions, all of which damage air quality.8 Further, as mentioned earlier, buildings produce 35% of the country’s carbon dioxide  emissions—the chief pollutant blamed for  climate change. Indoor air quality is inadequate in 30% of the buildings around the  world. These statistics underline the importance of changing construction practices.

To address these challenges, there is a need to develop effective approaches for  life cycle design and management of construction that will ensure their sustainability  in terms of improved physical performance, cost effectiveness, and environmental  compatibility.  Life  cycle  design  is  discussed  elsewhere.  Sustainable  design  has  to  consider three major aspects of sustainability: social, economic, and environmental  (see Figure 2).

The following are considerations for a sustainable building design:

• Resources should be used only at the speed at which they naturally regenerate  and discarded only at the speed at which local ecosystems can absorb them.
• Site planning should incorporate resources naturally available on the site,  such as solar and wind energy, natural shading, and drainage.
• Resource-efficient materials should be used in the construction of buildings  and in furnishings to lessen local and global impact.
• Energy and material waste should be minimized throughout a building’s  life cycle, from design through reuse or demolition.
• The building shell should be designed for energy ef ciency, considering  factors such as day lighting, passive ventilation, building envelope, internal  load, local climate, etc.
• Material and design strategies should produce excellent indoor environ- mental quality.
• The design should maximize occupant health and productivity. Operation and maintenance systems should support waste reduction and  recycling.
• Water should be managed as a limited resource.
• Location and systems should optimize employee commuting and customer  transportation options and minimize the use of single-occupancy vehicles.  These  include  using  alternative  work  modes  such  as  telecommuting  and  teleconferencing.

The  preceding  design  considerations  show  that  there  should  be  effective  inter- action  among  all  the  persons  involved  in  the  project  (client,  architect,  structural  engineer,  electrical  and  mechanical  engineers,  landscape  architect,  and  others)  at  all stages of the project. For concrete structures to be really sustainable, one should  adopt the holistic approach to the design based on the principle of strength through durability rather than durability through strength.