Choices in building material and construction methods for your house can vary widely as to their environmental cost. Energy use, pollution and habitat destruction are key considerations but the indoor environment created is also a consideration. The following is a comparison of common building materials.
Factors that are relevent to the envirocost (did I just coin a new word here) of materials are, transportation, raw material used, energy required in manufacture, longevity, carbon storage, recyclability, renewability, and sometimes the insulating value of the material. Recycled and reused material rates highly if it is locally available.
The use of locally available material can dramatically reduce environmental damage and usually reduces costs as well. Transportation is a major contributor to pollution, carbon emissions and costs. It follows that the less distance a product travels and the lower its weight, the less its cost, both financially and environmentally. The one caveat is that it must be commonly and easily available. Ideal are products that may normally be burned or land filled.
One of the best examples is earth that is available right at the building site. The soil in many areas is suitable for the construction of rammed earth walls. This method is well suited to warmer drier climates, but is also a possibility for much of Canada. For more detailed information,follow any one of the three following links. About rammed earth homes. Pictures of rammed earth construction. A more technical discussion of rammed earth construction in Canada.
In agricultural areas, straw is usually readily available and easily transportable. Straw bale construction is the most commonly known but straw is also sometimes used to manufacture panels that are commonly used as flooring underlay. Panels made from waste straw are also now being manufactured as an alternative to MDF, plasterboard and chipboard. Wheat straw is often used but many other types of straw could be utilized. Emphasis should be placed on waste straw. Straw in many areas needs to be incorporated into the soil to maintain or improve fertility. Proximity to manufacturers and cost would be considerations. Another alternative to straw bale construction is emerging. Straw formed into rope or cable is used to form columns or walls.
Paper can be recycled into building products such as panel board or papercrete. The practicality of the board would depend a lot on freight costs. Once again the environmental cost is probably closely related to the cost of the board delivered to you. In the case of papercrete it is possible to make your own. This link provides one papercrete recipe. Most papercrete recipes utilize a proportion of cement in the mix. Cement has a relatively high environmental cost but the proportion is usually small One persons method of making papercrete blocks. An intriguing building material but it may be better suited to farm outbuildings, sheds and garages than to homes. There is no shortage of information about it on the internet.
Much of North America and the Northern parts of Europe and Asia are in close proximity to sources of wood as a building material. Wood is a renewable resource and a versatile building material. The carbon storage in wood products is considerable. Virtually every part of a log is used and many species once considered weed are now used to manufacture building material. OSB (oriented strand board) can be manufactured using fire or insect killed wood. OSB and the Environment is a technical bulletin worth reading. Distribution networks for lumber and wood products are well established and efficient, reducing the impact of transportation somewhat. A well designed wood frame house has an excellent life expectancy.
Petroleum and natural gas provide the raw material for plastic. Cheap and light it is used in for the manufacture of many building products including flooring, siding, insulation, counter tops, plumbing and wiring, and in doors and windows. It is used extensively in appliances and to some degree in furniture.. Most of the environmental damage from plastic comes from single use packaging and recycling to date is not extensive. It’s lifespan in building materials is good. It’s use for piping in housing is such an improvement over metal that it has replaced metal almost entirely The environmental cost is probably less than the metals it largely replaces. It,s low-cost, low maintenance and light weight make it practical to replace wood in some cases such as siding. The use of plastic has made housing affordable for many more people. A disadvantage is that the smoke from plastics is very toxic in case of fire. The construction industry is the second largest user of plastics after packaging. Follow this link for more information on the use of plastic in building and construction.
Glass is a component of nearly every home. The energy requirements in manufacture are quite high but carbon emission would depend on the energy source. The raw material used is abundant. It is heavy and fragile which adds to transportation cost. It does have a low thermal resistance and requires special methods to improve the insulating value. Even the best windows are several times poorer than the surrounding walls at preventing energy transfer. Strategically placed, glass can be used for passive solar heat gain. This can offset much of its poor performance. Glass should be used carefully to prevent undue inefficiencies in the building envelope. An inert material, it is easily disposed of in land fills. Considerable amounts of glass can be recycled into new glass, but collection and transport can be a problem because of weight. For more information on glass production click here.
The short lifespan of asphalt shingles create an environmental cost. They are very heavy and recycling facilities are few. Most end up in landfills at the end of their lifespan. Newer types have life spans that are much longer without a significant increase in cost. Considering the cost of replacement alone should make you insist on the longer life choices. Lifetimes can vary considerably depending on location and roof styles.
Concrete is probably the most commonly used building material. The raw material for its production is usually available reasonably close. It is very heavy and transportation can add considerably to its cost. In my area concrete is usually delivered for about $150.00 per cubic metre. Some areas have prices of $250.00 and more. The production of cement is highly energy intensive and is responsible for considerable carbon emissions. Not a very environmentally friendly material choice, but a big winner in longevity. Some structures built with concrete by the Romans are still standing and even sometimes usable after more than 2000 years. Carbon cost of concrete manufacture has one estimate of carbon emissions. For a technical comparison of concrete and steel environmental cost follow this link.
Steel is another building material that is energy intensive in production. The thermal resistance of steel is very poor. It’s longevity, however, is very good. It is almost 100% recyclable and a high percentage of steel used today has been recycled. It is also quite heavy which adds to carbon footprint through transportation.
Other metals are similar to steel, but some are becoming very costly due to scarcity and increased mining costs..
Aluminium is highly energy intensive in production. The carbon foot print may not be very high, though, since much of the manufacturing is done where low-cost hydroelectric is available. It is also considerably lighter than other metals, lessening its carbon cost through transportation. To recycle aluminium requires less than 6% of the energy as producing new aluminium from bauxite. Recycled aluminium accounts for at least half of the product produced in North America. This article discusses the energy cost of aluminium production, and ways to reduce it.
Any building material has an environmental cost associated with it. The environment is best served by using the least material possible, It is worth considering the use of lower cost alternatives wherever possible.