Impact: why, what and how are we measuring it
Do you ever feel too small to make a difference, or overwhelmed by the news about the environment? Are you worried about the future? Do you easily give up on sustainable behaviour because you don't see the effect it has?
We decided to show the impact of our clothes mainly for two reason. First one is so that you see that no matter how small it seems at first, what you buy, wear and wash has a substantial impact on both your health and the environment. Then, we also want to motivate you to continuously make more sustainable choices in your life.
In the following paragraphs we will explain:
- what kind of impact we decided to measure,
- which academic literature we used to get the data from, and
- formulas we generated to calculate our impact.
In addition, we will clarify the limitations of our formulas by indicating the data gaps in the current academic literature.
Impact which we measure
For now, we are measuring our impact in 4 areas:
A) Kilograms of CO2 absorbed
B) Kilograms of emissions (greenhouse gasses) avoided (prevented from being emitted)
C) Litres of water saved
D) Pieces of microplastic not released
We will be calculating all of these four measures for each piece of clothes that we make (which is equal to pieces of clothing that we sell), and we will be presenting the total amount.
A) Kilograms of carbon dioxide (CO2) absorbed
We excel in this area because we are using hemp as our main fabric, which is known to be one of the fastest CO2-to-biomass conversion plants available.
Classified as C4 plant, hemp is 400% more efficient in CO2 absorption than any forest or commercial crop.
According to the document: "The Future for Hemp, International perspective on the rapid rise of hemp cultivation", which is published by European Industrial Hemp Association, one hectare of industrial hemp can absorb 15 tonnes of CO2 per hectare. In addition, it is possible to grow two crops per year, so CO2 absorption can be doubled, reaching 30 tonnes per hectare.
However, for our formula, we are using a report issued by Good Earth Resources "The Role of Industrial Hemp in Carbon Farming". According to this report one hectare of Hemp absorbs 22 metric tonnes of CO2. This reports also states that absorption is doubled if two crops per year are grown. For our formula, we haven't taken into account this double effect.
As we are displaying our impact in kilograms, for us this means that one hectare of industrial hemp absorbs 22 000 kg of CO2.
According to the study "The Potential for Hemp: Locally Produced Organic Textiles", published by The Ecology Centre, Carshalton, UK, one tonne of hemp could comfortably be grown on 0.2 hectares, and, a tonne of hemp would produce, at conservative yields, 150 kg of line or high quality fibre. That means that one hectare will give 750 kg of fibre. As one hectare absorbs 22 000 kg of CO2, one kilogram absorbs 29.33 kg of CO2.
The final formula calculated for each garment is:
Kg of CO2 absorbed = weight of the garment in kg * % of hemp fibre in the fabric * 29.33
This model doesn't take into account that not all of the hemp plant is used to make a yarn, even though all of it is used to absorb CO2. Also, it doesn't take into account losses of fibre that happen during the production of fabric.
Both of these two points don't change the fact that CO2 was absorbed, so we have decided not to take them into account until there is more data available.
B) Kilograms of greenhouse gasses avoided
While the first measurement was about CO2, the second is about all greenhouse gasses.
According to the study: "Accounting for greenhouse gas emissions of materials at the urban scale-relating existing process life cycle assessment studies to urban material and waste composition", done by Kissinger, Moore et al., textile industry is identified as one of the largest producers of greenhouse gasses: together with aluminium, textile generates the highest greenhouse gasses emission per unit of material.
Carbon dioxide, Methane and Nitrous oxide are naturally present in the atmosphere, and human activity is increasing their concentration above the balance. The other types of gases, such as chlorofluorocarbons and hydrofluorocarbons, are not naturally present in the atmosphere and are created only due to human activities.
Each of these gasses trap different amounts of heat and have different global warming potential, which is presented as CO2 equivalent.
In our formula we will also present all greenhouse gasses in terms of CO2 equivalents.
To generate the formula we are comparing emissions generated by production of fabric which we use (Hemp and Tencel) with emissions generated by production of fabric which we don't use (like polyester).
We are using a study "Life cycle assessment of hemp cultivation and use of hemp-based thermal insulator materials in buildings", published in Environmental Science & Technology, as it was the only peer-reviewed study we found on a topic. According to this study, producing Hemp fibre generates 0.1 to 0.2 kg of CO2 equivalents, per kg of fibre. This number does not include CO2 already sequestered in fibre during the growth of a plant. In this way, we are separating our second impact from the first, and we are not counting double the CO2 already presented in the first formula.
Worth noting are two additional studies which we decided not to use in our formula, as they are not peer reviewed:
- Barth and Carus in their study from 2017: "Carbon footprint and sustainability of different natural fibres for biocomposites and insulation material" calculated that 1 kg of hemp fibre contributes to 0.76 kg of CO2 equivalents if mineral fertilisers are used and 0.6 kg if organic fertilisers are used.
- Study published by Stockholm Environmental Institute: "Ecological Footprint and Water Analysis of Cotton, Hemp and Polyester" done by Cherrett et al., presents much higher CO2 equivalents emissions from producing hemp, ranging from 3.5 to 6 kg of CO2 per kg of fibre. In addition to not being peer reviewed, this study seem to contain an error: the carbon footprints are in the range from 2 to 10 kg of CO2 per tonne of fibre, while similar numbers are usually per kg.
Shen et al. in their study from 2010: "Environmental impact assessment of man-made cellulose fibres" calculated that 1 kg of Lyocell fibres contributes to 0.05 to 2.3 kg CO2 equivalents, excluding CO2 already sequestered in the fibre.
There are other studies about contribution of Tencel Lyocell, but again, as not peer reviewed, we have decided not to use them.
The last piece of information needed for our formula are the emissions from Polyester fibre. For this, we went again to the researchers we already know: Shen at al in their other study from 2010: "Open-loop recycling: a LCA case study of PET bottle-to-fiber recycling" stated that 1 kg of polyester fibre produced in Europe contributes to 4.1 kg of CO2 equivalents. Worth noting is that recycled polyester fibres contribute 1.7 kg, which is still higher than Hemp and Tencel.
To calculate how many kg of greenhouse gasses we have avoided, we compare Polyester emissions with Hemp and Tencel emissions:
For our formula we need three numbers:
X = Weight of the garment in kg * Emissions from 1 kg of Polyester
Y = Weight of the garment in kg * % of the hemp fibre in the fabric * emissions from 1 kg of Hemp
Z = Weight of the garment in kg * % of the Tencel fibre in the fabric * emissions from 1 kg of Tencel
The final formula is calculated for each item as:
Kg of emissions from greenhouse gasses avoided = X-Y-Z
C) Litters of water saved
Fashion industry usage of water can be divided in two general areas:
- agronomic cultivation (water used for crop growth, cultivation, pesticide and fertiliser application and harvesting);
- manufacturing (water used in ginning, baling, spinning, weaving, finishing, dying and printing).
In the study: "Ecological Footprint and Water Analysis of Cotton, Hemp and Polyester", published by Stockholm Environment Institute, for the production of 1 kg cotton lint (fibre got from the cotton seed that still needs to go through the process of cleansing, carding, combing, roving and spinning), between 9 799 litres and 9958 litres of water are required (without taking into account the rainfall, groundwater reserves and soil moisture capacity, which can be as much as 35% of the delivered water) (Cherrett, Barrett, Clemett, Chadwick, & Chadwick, 2005).
To measure our impact, however, we will use findings from World Wildlife Fund (WWF) which seems to be more complete. According to WWF, 20 000 litres of water are needed to produce 1 kg of cotton fibre.
To generate our formula we will use the data from already mentioned study: "Ecological Footprint and Water Analysis of Cotton, Hemp and Polyester" done by Cherrett, Barrett, Clemett, Chadwick, & Chadwick, and published by Stockholm Environmental Institute, according to which traditional hemp processing requires 343 litres of water per kg of useful hemp fibre. (This study also examined experimental method of hemp fibre production, which uses 2123 litres of water to produce 1 kg of usable hemp fibre, but as this method is proven to be costly and unlikely used, we will not use its numbers in our formula).
When comparing water needed for 1 kg of cotton with water needed to produce 1 kg of hemp, we can conclude that each kg of hemp saves 19657 litres of water.
To calculate our impact, we are applying the following formula on each garment:
Litres of water saved = Weight of the garment in kg * % of hemp fibre in the fabric * 19657
D) Pieces of microplastic not released
Washing clothes made from synthetic materials has been identified as a huge source of microscopic fibres released to the environment. According to the AISE reports from 2013, a massive amount of 12 709 tonnes of microfibres (both natural and microplastic) are being released each year into rivers, the sea and the ocean, in Europe alone.
According to the study "Microfiber Release from Real Soiled Consumer Laundry and Impact of Fabric Care Products and Washing Conditions", published by the scientific journal Plos One, each kg of fabric is releasing an average of 114 mg of microfibres during a standard washing cycle (which means that 6 kg are releasing 684 mg). According to this study, 96% of the fibres released were natural and 4% were synthetic (nylon. polyester and acrylic).
In the study "Release of synthetic microplastic plastic fibres from domestic washing machines: Effects of fabric type and washing conditions", Napper and Thompson estimated that an average 6 kg wash load could result in releasing:
- 137 951 polyester-cotton fibres (machine was loaded with clothes made of polyester and cotton blend);
- 496 030 polyester fibres (machine was loaded with clothes 100% made of polyester);
- 782 789 acrylic fibres (machine was loaded with clothes 100% made of acrylic).
For our formula we will use the study: "Microfiber release from clothes after washing: Hard facts, figures and promising solutions" published by Plastic Soup Foundation, according to which a moderate load of laundry releases 20 million fibres of micro plastic. If we estimate that moderate load of laundry is 6 kg, that leaves us with a bit more that 3 million micro plastic fibres per kg of laundry.
To calculate our impact, we will use the following formula:
Pieces of microplastic not released to water flows = weight of the garment * 3 000 000
This formula is limited because it only takes into account single washing cycle. In reality, the impact is much higher.
Our plans for the future
As new research on these for topics is being published, we will continue to improve our current formulas. At the same time, we are looking forward to measure our impact in other areas, such as: energy savings, contributions to local economies, and other.