Some Considerations of Sustainability...

 

... in Steel Frame 

Construction

Manufacture

• The raw materials for steel are iron ore, coal, limestone, air, and water. The ore, coal, and limestone are minerals whose mining and quarrying cause disruption of land and loss of wildlife habitat, often coupled with pollution of streams and rivers. Coal, limestone, and low-grade iron ore are plentiful, but high-grade iron ore has been depleted in many areas of the earth.
• Supplies of some alloying metals, such as manganese, chromium, and nickel, are becoming depleted.
• The manufacture of a ton of steel from iron ore by the basic oxygen process consumes 3170 pounds of ore, 300 pounds of limestone, 900 pounds of coke (made from coal), 80 pounds of oxygen, and 2575 pounds of air. In the process, 4550 pounds of gaseous emissions are given off, and 600 pounds of slag and 50 pounds of dust are generated. Further emissions emanate from the process of converting coal to coke.
• The steel industry has worked hard to reduce pollution of air, water, and soil, but much work remains to be done.
• The embodied energy of steel produced from ore is about 19,200 BTU/pound.
• Most structural steel in North America is made from recycled scrap; its embodied energy is only about 39 percent of that of steel made from ore.
• Sixty-six percent of all steel in eventually recycled, which is a very high rate. In a recent 10-year period, 1.2 trillion tons of steel were recycled worldwide. 

 Construction

• Steel fabrication and erection are relatively clean, efficient processes, although the paints and oils used on steel members can cause air pollution.
• Steel frames are light in weight as compared to concrete and masonry frames that would do the same job. This means that a steel building generally has smaller foundations and requires less excavation work.
• Some spray-on fireproofing materials can pollute the air with stray fibers.

  In Service

• Steel framing, if protected from water and fire, will last for many generations with little or no maintenance.
• Steel exposed to weather needs to be repainted periodically unless it is galvanized or given a long-lasting polymer coating.
• Steel framing members in building walls and roofs should be thermally broken or insulated in such a way that they do not conduct heat between indoors and outdoors.
• When a steel building frame is demolished, its material is almost always recycled.
• Steel seldom causes indoor air quality problems, although surface oils and protective coating sometimes outgas and cause occupant discomfort.

 

Some Considerations of Sustainability ...

... in Brick Masonry Construction

• Clay and shale, the raw materials for bricks, are plentiful. They are usually obtained from open pits, with the attendant disruption of drainage, vegetation, and wildlife habitat.
• Because of the energy used in its firing, brick is a relatively energy-extensive product. The energy embodied in an average brick is 14,300 BTU. The usual energy sources for brick kilns are oil, gas, or coal. Air pollution can result from improperly regulated kilns.
• Clay and shale are found almost everywhere. The majority of bricks come from regional plants, which reduces the energy needed to ship them.
• Bricks last a very long time and usually an be recycled when a building is demolished.
• Brick masonry is not associated with indoor air quality problems.
• The thermal mass effect of brick masonry can be a useful component of fuel-saving natural heating and cooling strategies such as solar heating and nighttime cooling.
• Mortar is made of minerals that are generally abundant in the earth. Portland cement and lime are energy-intensive products.
• Relatively small amounts of waste are generated on a construction site during the construction of a brick building, including partial bricks, unsatisfactory bricks, and unused mortar. These wastes generally go into landfills or are buried on the site.
• When a brick building is demolished, the bricks may be cleaned of mortar and reused. However, the more usual practice is to dump the bricks and mortar in a landfill or to use them as fill on a construction site.

 What is sustainability?

Some Considerations of Sustainability...

... in Site Work, Excavations, and Foundations

Site Selection 

• Buying and renovating an existing building rather than building a new one saves a great deal of building material. If the existing building has been scheduled for demolition, it also avoids dumping an enormous quantity of material into a landfill.
• Building on a  damaged site, and designing the building so that it helps to restore it, benefits the environment rather than degrading it.
• Building on agricultural land takes that land out of production forever.
• Building in forests and on wetlands and prairies destroys wildlife habitat.
• A building that is well connected to existing networks of public transportation , and to pedestrian and bicycle paths, pays environmental dividends every day for the life of the building by saving fuel, reducing air pollution from automobiles, and minimizing commute times.

What is Sustainability?

          Sustainability may be defined as meeting the needs of the present generation without compromising the ability of future generations to meet their needs. By consuming fossil fuels and other nonrenewable resources, by building in sprawling urban patterns that cover extensive areas of prime agricultural land, by using wood from forests that are not replanted, by allowing topsoil to be eroded by wind and water, and by generating substances that pollute water, soil, and air, we have been building in a manner that will make it increasingly difficult for our children and grandchildren to meet their needs for buildings and healthy lives.

          On the other hand, if we reduce building energy usage and utilize sunlight and wind as energy sources for our buildings, we avoid depletion of fossil fuels. If we reuse existing buildings imaginatively and arrange our new buildings in compact patterns on land of marginal value, we minimize the waste of valuable land. If we harvest wood from forests that are managed in such a way that they can supply wood at a sustained level for the foreseeable future, we maintain wood construction as a viable option for centuries to come. If we protect soil and water through sound design and construction practices, we retain these irreplaceable resources for our successors. If we systematically reduce or eliminate the various forms of pollution emitted in the processes of producing and operating buildings, we keep the environment clean in perpetuity. It is often possible to do these things without increasing the monetary costs of constructing and operating buildings, and in some cases actually to reduce these costs.

          Realization to these goals is dependent on our awareness of the environmental problems created by building activities, knowledge of how to avoid these problems, and skill in designing and constructing buildings that harness this knowledge. Sustainable design and construction, also called "green" building, is steadily becoming the goal of more and more building owners, architectural and engineering firms, contractors, and building operators, among them some of the largest organizations in each field.

          Sustainability must be addressed on a life-cycle basis, from the origins of the materials for a building, through the manufacture and installation of these materials and their useful lifetime in the building, to their eventual disposal when the building's life is ended.

Considerations of sustainability:
       in Site Work, Excavations, and Foundations
       in Brick Masonry Construction