Monday, September 13, 2010

How Much Embodied Energy is in Your House?

Basically Buildings Need Materials
When you factor in the full picture of all the processes of manufacture, like what was involved with where, how etc the materials arrived at the building site; such as how much energy did it take to process the materials, including the mining/harvesting of the raw materials, including the use of tools, fuel for transport, etc.  How much pollution did the whole process create and what was the cost to the environment and how much would it cost to completely rectify the environment to before the whole process started and what were the costs and impacts on human health. Then, also factor in the energy used on site during the construction. Then at the end of the buildings life cycle, the energy and costs for the disposal of the building material.  

So; Embodied energy is the energy used through all of the stages of the production of a building.
With embodied energy there is also embodied emissions; carbon emissions. It has been reported that for around every dollar spent, there’s one kilogram of carbon emissions.

The choice of materials, method of construction and some common sense, determines the amount of energy embodied in the structure of a building.
The design of a building should also then factor in the following:
Which Climate Zone is the building
What’s the transport distances involved
What’s the embodied energy content of the available local materials

Starting at the lower end of embodied energy we have local timber, local stone, local mud bricks and the best . . . local recycled materials. The embodied energy in sawn hardwood that is air dried, is about a quarter less than kiln dried and twenty times less than laminated veneer lumber or MDF. In the case of LVL’s [laminated] and MDF, this is due to the energy used in the heating process in the first instance and with the extra manufacturing and glue. Then at the high end of embodied energy are aluminium, copper and plastics. These materials have hundreds of times more embodied energy than the air dried sawn hardwood.

Design the building for a long life 
In some cases the choice of a high embodied material is necessary; For example, large amounts of thermal mass, high in embodied energy, such as concrete and brick, can significantly reduce heating and cooling needs in a well designed and insulated passive solar house.  Also the choice of a high embodied material, such as steel, may last longer, thus the building lasts longer. When the building lasts longer, the energy used for the building’s existence is spread over a larger time, thus in effect lessening the amount of energy.

>Avoid building a bigger house than you need.  This will save materials.

>Make use of materials from demolition of existing buildings. Where possible, recycle construction wastes.

>Use locally sourced materials. This reduces transport.

>Select materials that can be re-used or recycled easily at the end of their lives.

>Give preference to materials manufactured using renewable energy sources.

At the end of the day
If every building was considered with keeping the embodied energy to a minimum, not only would the price of the building be less but it would help the environment and thus everyone’s health.

Healthy Planet, Healthy People  

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