Impact Category Definitions

What are all these new impact categories eTool can now measure?  Below are some definitions:

Climate Change impacts result in a warming effect of the earth’s surface due to the release of greenhouse gases into the atmosphere, measured in mass of carbon dioxide equivalents.

Stratospheric Ozone Depletion is caused by the release of gaseous chemicals that react with and destroy stratospheric ozone. Although the Montreal treaty has significantly reduced the use of the most damaging substances and there is evidence that the abundance of ozone depleting gases is reducing in the atmosphere, some releases of ozone depleting chemicals still occur.

Acidification Potential provides a measure of the decrease in the pH-value of rainwater and fog, which has the effect of ecosystem damage due to, for example, nutrients being washed out of soils and increased solubility of metals into soils. Acidification potential is generally a regional impact and is measured in mass of sulphur dioxide equivalents. The mechanism dominating the acidification impacts is the combustion of fossil fuels, release of sulphur dioxide and nitrogen oxide which dissolves with condensed water in the atmosphere and falls as rain. The term acid rain describes severe incidents of this mechanism.

In general terms, Eutrophication Potential provides a measure of nutrient enrichment in aquatic or terrestrial environments, which leads to ecosystem damage to those locations from over enrichment and is measured in mass of phosphate equivalents.

Tropospheric Ozone Formation Potential is the creation of lower atmospheric ozone (commonly known as smog) due to the mechanism of VOCs reacting with sunlight. In particular, the release of carbon monoxide from steel production is predominant; however other releases such as nitrogen oxide, sulphur dioxide and methane also contribute significantly to POCP.

Mineral & Fossil Fuel Depletion (Abiotic Depletion) provides an indication of the potential depletion (or scarcity) of non-energetic natural resources (or elements) in the earth’s crust, such as iron ores, aluminium or precious metals, and it accounts for the ultimate geological reserves (not the economically feasible reserves) and the anticipated depletion rates. It is measured in mass of antimony equivalents.

Human Toxicity, in general terms, refers to the impact on humans, as a result of emissions of toxic substances to air, water and soil, and is expressed in terms of damage to human health by the index mDALY (1/1000th of a disability adjusted life year). The latest LCI dataset is now also reporting Human Toxicity with the USEtox Characterisation Method which is a well established method and readily available.

In eToolLCD, we now have three indicators for Human Toxicity – Human Toxicity Potential (DALY), Human Toxicity Cancer and Non-Cancer (CTUh).

Human Toxicity Potential (DALY) – Human results from persistent chemicals reaching undesirable concentrations in each of the three elements of the environment (air soil and water). This leads to damage to humans, animals and eco-systems. The modelling of toxicity in LCA is complicated by the complex chemicals involved and their potential interactions. Human Toxicity Potential (HTP) takes account of releases of materials toxic to humans in three distinct media being air, water and soil. The toxicological factors are calculated using scientific estimates for the acceptable daily intake or tolerable daily intake of the toxic substances. The toxicological factors are still at an early stage of development so that HTP can only be taken as an indication and not as an absolute measure of the toxicity potential. In this case the indicator is measured in Disability Adjusted Life Years (DALY).

Human Toxicity Cancer/Non-Cancer (CTUh)– Life cycle impact assessment of toxicity takes into account the fate, route of exposure and toxicity impact of toxic substances when released to air, water or land. Categories of chemical substances commonly accounted for are pesticides, heavy metals, hormones and organic chemicals. Human toxicity, cancer measures the potential for toxic releases or exposure to cause cancer in humans.

If you have any questions regarding how it should be reported for Green Star v1.2, please refer to this discussion topic.

Land Use is measured in years of use of arable land (m2.year). This describes the area and time land is occupied by production systems both natural and industrial for the production of the building materials but not the occupation of the building itself. While not strictly an impact category it is linked to general land use pressure and is therefore a proxy for biodiversity and other land competition impacts.

Water Footprint provides an indication of the total net input of water used throughout the life cycle of the building. Fresh water can be derived from renewable sources (rain water) and somewhat non-renewable resources (aquifers). The Water Footprint indicator distinguishes from these sources and provides an understanding of the depletion of fresh water sources, in particular from non-renewable resources.

The Water Scarcity indicator (H2O S) expands on the Water Footprint indicator by not only distinguishing from these sources and providing an understanding of the depletion of fresh water sources but also relating this depletion to scarcity in the freshwater supply in the local region.

Ionising Radiation covers the impacts arising from the release of radioactive substances as well as direct exposure to radiation. The impact is expressed in terms of damage to human health by the index uDALY (1/1,000,000th) of a disability adjusted life year.

Ecotoxicity refers to effects of chemical outputs on nonhuman living organisms. Expressed in comparative toxic units (CTUe) it provides an estimate of the potentially affected fraction of species integrated over time and volume per unit mass of a chemical emitted.

Particulate Matter is defined as a mixture of solid and liquid particles of organic and inorganic substances resulting from human activities and suspended in the atmosphere. Several studies show that PM causes serious adverse health effects, including reduced life expectancy, heart disease, lung cancer, asthma, low birth weight, and premature birth. Precursors involved in PM formation include sulfur dioxide (SO2), nitrogen oxides (NOx), ammonia (NH3), and volatile and semivolatile organic compounds. Measured as either PM2.5 (particulate matter smaller than 2.5 micrometers) or PM10 (particulate matter between 2.5 to 10 micrometers). Finer particles can travel deeper into the lungs and are usually made up of materials that are more toxic therefore PM2.5 can have worse health effects than the coarser PM10.

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