Construction Material Selection

There are three types of materials used in the construction of buildings. Those that are harmful to the environment in their production or use , those that are harmless and those that we aren’t sure about. There are  a number of methodologies for assessing materials and their use and many sources of information. I thought that it would be useful to summarise these in one place.

My view on this topic generally is that we have put it into the ‘too difficult to think about now’ box because there are no compelling reason’s to do so. There are no regulations to direct us in this matter, and there is no link to the market to tell us what the end users of our buildings want from us. I am convinced that a normal occupant of any building would be concerned to hear that there are materials used in the construction of their building that can be damaging to their health in any circumstances, but we make little or no effort to ensure that our buildings are as benign as possible for the occupant, and make no effort to communicate about it to the market. It is a specific area of market failure. If we compare the construction market to the food market, there are substantial efforts in the latter to explain to consumers what goes into their food, where it comes from, and concerns about health of consumers and farmers has largely led to the growth of the organic food market with no external regulation.

For BREEAM and Code for Sustainable Homes projects, there are guidelines to follow in the form of credits for Materials, which will point us towards the BRE Green Guide to Specification for Materials, which provide us with an A-E rating for the material in question. However it is not immediately obvious to any observer how or why the rating is given. There was a lot of concern in the industry when UPVC windows and timber windows were both found to be capable of scoring the highest rating. This is despite the fact that UPVC windows produce a lot of dangerous chemicals when burned. This demonstrates the benefits and problems of such simplified rating systems. If the analysis is sufficiently broad, almost any material can be found to have some advantage over another.

At the other end of the spectrum there is the Cradle-to-Cradle methodology which is really only interested in where the material came from, and where it goes after it has been used, it doesn’t concern itself with the operational phase at all. The Cradle-to-Cradle philosophy tests materials for either being sources of biological nutrients, in which case they can be composted, rotted, or otherwise consumed after use, or they are technical nutrients in which case they can be reused. In the case of composite materials the process for separating the two materials needs to be considered.

Both of these methodologies rely on a technique called LifeCycle Analysis (LCA). This aims to assess the impact of the material on the environment during its production, operation and recycling or reuse. LCA tools help to smooth the process of analysis by providing databases of material properties and impacts for the analysist to use, and lowers the costs of carrying out analysis. There is an ISO standard approach to LCA described in ISO 14044.

When selecting a material for use, you should ask yourself the following questions:

– is the material obviously harmful to the environment, to its producers, constructors or end users? The REACH database will help you to identify if it is a banned or harmful substance.

– How do I compare two similar materials? When comparing two similar materials check whether either one has an Environmental Product Declaration (EPD) which is a report on its LCA. If both have one, then you should be able to compare the two materials.

– How do I compare one construction system to another? If the construction system you are using the material in has a Green Guide rating, then that will enable you to compare it to other similar systems using the same material.

– Am I worrying too much about small stuff? You can use a tool like eTool to test the overall impact of using one material in the building compared to another material, which will help you to assess the total impact. Otherwise there is a danger of spending a lot of time worrying about the wiring, when the main impact will come from the construction materials.

The field of material impacts is growing rapidly as we learn more and more about the harmful impacts materials have on us and on the environment around us. There is an increasing number of tools and protocols to help designers, contractors and clients to understand the materials that they work with every day. We shouldn’t wait for regulators to tell us things that we can already find out for ourselves, and our end users will be grateful that we took the trouble to make their buildings safer and more environmentally friendly.



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