Comparative Life Cycle Assessment Examples

Introduction

What is a comparative life cycle assessment?? A comparative L.C.A is used to compare the environmental impact of two or more products used in the same situation.

LCA comes into play when your mission is to choose a product with the lowest possible environmental impact for marketing “green” construction or wanting to understand the environmental impact of that product for use.

An example of this this would be in selling passive homes or NZEB (nearly zero energy buildings)

This assessment will focus on steel and timber studs in residential use both 100mm wide by 2.4 meters long. We will go through four stages for each product, extraction, manufacturing, use and end of life.

All comparative life cycle assessments fall under ISO

This involves the cutting of grown trees to be sent for manufacturing at a later stage. The extraction of timber usually happens during clear-felling or thinning.

Thinning is removing the trees that won’t make the grade for use in construction. Eliminating the weaker trees helps the others grow and improves the quality of the forest. This can happen up to 5 times over a forest rotation.

Clear-felling is the harvesting of all trees deemed well enough for use in manufacturing for construction proposes. Usually in conifer forests the age of the trees is up to 50 years of age.

Manufacturing Manufacturing of timber happens at the saw mill. When the unprocessed logs arrive they are sorted and stored, by, size, species and diameter. They will stock pile enough timber to ensure continues use to avoid down time due to weather. Which also makes the energy consumption of the saw mill more cost effective.

The manufacturing process starts with the debarking of the trees, this is a mechanical process where the logs are feed through a debarker at the mill, and this will help the mill in the long term as there is less wear and tear on the blades and machinery. It also allows the workers at the mill to sort and arrange the best logs for

This is the cutting o all log to the straightest lengths.

This helps when cutting into standard lengths for use in construction. (FAO. corporate document repository , n.d.)

Use / recycling

When using timber studs for non-load barring construction, you set them out at 400 centres and 1200 centres. This is for the plaster board to fit perfect and for the there to less waste, and better buildability. When it comes to reuse it’s not too easy to recycle as steel. The process for recycling timber studs popular in the 90s (wikipedia, n.d.) Gaining more momentum as the treat of climate change became ever stronger. With the focus of consumers wanting a more sustainable product, manufacturers had to change the way they thought about how and what type of product they got to market.

Conclusion

While both are readily available as a natural resource, both products have been mastered in the art of manufacturing to market. Steel studs are easier to fit, easier to recycle and this recyclability is a prominent part of the primary process for steel manufacturing, timber can also be very