The Environmental Impact Comparison of Conventionel Shoes vs Sustainable Shoes

Comparing the data on conventional shoes and how they compare to sustainable/recycled shoes.

FACTS AND DATA

Greenly World

3/11/202411 min read

The earliest known pair of shoes is actually unclear, some state it's around 9000 years ago and others may indicate as much as 30.000 years ago more or less. In any case, they've been around for a very long time and for good reason, shoes have made outdoor activities much easier, especially more intense exercise such running or cycling/biking. It's definetely throughout the years become a thing in the fashion industry, and the production of shoes is still growing.
The question becomes, is this a trend that is good for the environment and is the alternative of shoes labelled as 'sustainable' actually sustainable when the data is presented?
Well, we've looked into this, made data analysis on both conventional and sustainable shoes to give a rough estimate on their environmental impact, and a conclusion based on it.

Table of Contents:

Current state of Shoe Production
The CO2 Emission of Conventional Shoes in Comparison to Sustainable Shoes
Energy Consumption (Conventional Vs Sustainable)
Water Consumption (Conventional Vs Sustainable)
Real Case Example on The Emissions of a Sustainable Shoe

Conclusions

Current State Of Shoe Production

It would be seem as an exaggeration to say this but the amount of shoes produced is much higher than we think most people would guess. According to recent numbers, it's estimated that there are 24 billion shoes produced globally each year, which is an enormous number. From that only 5 % of these shoes are actually recycled, and the rest; they end up in landfills.

The impact of this, is that the shoes can release toxic chemicals that is emitted to the soil and groundwater, which in other words is environmental pollution. Further, the incineration (burning) of shoes isn't a good idea either since it releases harmful chemicals to the atmosphere which leads to air pollution. Recycling rates as we can imagine would definetely reduce these types of environmental impacts.

However, that doesn't necessarily solve the root of the problem. Almost half of all shoes are made from synthetics, such as virgin plastics, and another portion is made from leather. The problem lays in these shoes take a very long time to degreade in nature; shoes made from leather takes around 25 - 40 years, meanwhile synthetic shoes can take 100 years before they biodegrade and some can even take up to 1000 years.

The actual CO2 emissions emitted from a production of a pair of shoes is estimated to be 14 kg (30 pounds). There are definetely some who would argue it's a bit higher for the leather shoes, but this average of 14 kg (30 pounds) per shoe is the standard that most based it upon due to a study made from MIT in recent years.

From that we want to compare this with the CO2 emission of a pair of sustainable shoes. It is important to note what defines a sustainable shoe, for simplicity we've defined it to be a 100 % recycled shoe. This makes calculations a bit easier, however shoes made from other materials that are non plastics will be introduced later as a mini case with few data.

The CO2 Emission of Conventional Shoes in Comparison to Sustainable Shoes

As stated earlier, 24 billion shoes are produced globally each year and with an average CO2 emission of 14 kg (30 pounds) per pair of shoes. As seen from below, it's a simple equation because it only requires to multiply the amount of CO2 per pair of shoe with the actual production of 24 billion shoes. As seen below from table 1, this would result in a total CO2 production of 336 million tons, that's the equivalent of 1.4% of the total CO2 emission globally by all industries.

From what we could find the CO2 emission of a recycled shoe is no suprising smaller. However the exact amount is fluctuating but the trends seems to be around 10 kg per of shoe. As seen from the following Graph 1 this gives an overall picture.

As seen from the Graph 1 the conventional shoe emits 336 mio. tons of CO2e in comparison to the sustainable shoe which in total would emit 240 mio. tons of CO2e. This is only a scenario since not all shoes are made from recycled materials for clarification, however hypothetically that would result in a CO2 reduction of 28 % on global scale.

Energy Consumption (Conventional Vs Sustainable)

Looking beyond CO2 emissions which is a very popular and normal metric, it can be very beneficial to compare both the energy consumption as well as the water consumption to give a more complete picture of the environmental impact. These are just some indicators, there are others as well that could be considered but for simplicity we went with these.

In terms of the energy consumption pr pair of shoe it is estimated that is it equivalent to 3.5 MJ. For leather shoes it's estimated to be around 107.25 MJ. With this known and the amount of shoes produced it's a simple multiplication, and this results in an energy consumption of 84 mio. GJ/Year as seen from Table 2 and Graph 2 below.

Clearly the difference is very significant as the energy that is saved (as seen from the table) is around 522.410 GJ/Year. To give some perspective some rough estimates on what would look like:

  • Homes (Iceland):
    Enough energy to power approximately 52000 average Icelandic homes for one year.

  • Mobility (Nigeria):
    Fuel energy equal to operating 13.8 million Nigerian motorcycles annually.

  • Electricity (Indonesia):
    Annual electricity needed for 145000 average Indonesian households.

  • Industry (India):
    25% of energy required by India's annual plastic products manufacturing.

  • Renewables (China):
    Matches energy from 52000 average Chinese solar rooftop systems.

  • Heating/Cooling (South Africa):
    Meet demand of 52000 low-income South African households annually.

  • Shipping (Japan):
    Fuel for over 5100 annual cargo ship voyages between Japan/Australia.

  • Homes (US):
    Power 52,000 average US homes for a year.

    Note: These are just rough estimates, they may be a bit off.

Producing new plastic from recycled material uses only 2/3 the energy of raw materials. With this information it made it possible to give an estimate on how much energy it would require globally to produce the recycled shoes. This gives an estimate of 1.53 milion GJ/Year. To give a illustrative represantation of this, graph 2 below shows this.

Water Consumption (Conventional Vs Sustainable)

Looking at the water usage of shoes is the next interesting data look at. There are more leather shoes produced than synthetic shoes, and the amount of water consumption it takes just to make a pair of leather is roughly 8000 liters or 2113 gallons of water, which is a lot.
In comparison with synthetic shoes it was a bit more difficult to search so we might a rough estimate. The average shoe weight is around 1.35 lbs (612 grams) on average. Since it takes around 22 gallons (83 liters) to produce 1 pound (0.45 kg) of plastic, it make the estimate easier to calculate. By multyplying the amount of shoe made from plastic with the weight of a pair of shoes, and lastly multiplying the amount of water it takes for one pair of shoes made from plastic it gives a total water consumption of 1.120.500.000. 000 liters.

This number has to be added with the number of shoes made from leather (14 billion) and the remaining from synthetics (10 billion)

Adding these two together gives a total water consumption of 113.120.500.000.000 liters also known as 113 trillion liters of water. This can be seen from Graph 3.

The recycled/sustainable shoe was estimated according to EPA that has concluded that recycling plastic saves 60% of resource extraction activities. Therefore since water is a resource applied in the production, we can simply determine 60 % out of the total water consumption from the conventional shoes and get around 67.8 trillion liters of water. Making a simple substraction results in a saving of roughly 45 trillion liters of water. To give an idea on how much that is in examples it's the following:

  • Municipal Supply:
    Equal to over 1.5 times the annual household water usage of Tokyo (population 37 million).

  • Agriculture:
    Could irrigate an area more than 2.5 times the size of rice paddies in Vietnam, a major producer.

  • Households:
    Equivalent to the daily water needs of over 600 million people, greater than the populations of Indonesia or Brazil.

  • Freshwater:
    Enough to fill over 45 Lake Victories, the largest reservoir serving Cairo, Egypt (170 billion liter capacity).

  • Drinking Water:
    Could meet over 45 years of piped water needs for Karachi, Pakistan (population 15 million).

  • Industry:
    Exceeds the annual process water demand for all of India's automotive manufacturing industries.


Nb: These are just estimates, take with with a grain of (himalayan) salt. But does examples put things into perspective

Real Case Example on The Emissions of a Sustainable Shoe

We've looked at rough estimates based on if recycled shoes from synthetics (also in the category of sustainable shoes) and how it compare with conventional shoes made from virgin plastics and leather.

To give a more concrete example of how much CO2 a pair of sustainable shoes are actually emitting, we've looked at a shoe that's made from mostly natural sustainable resources with very few recycled elements. This pair of shoes has a calculated number on the amount of CO2 it's producing.

The example within this theme will be Case 1.

The shoe they have produced is actually a lot lower than most of the recycled shoes in the market, including big brands. It actually only emits 4 kg (8.8 pounds) of CO2 per pair of shoe, perhaps the shoe that emits the least. In addition, the weight of the pair is only 240 grams (0.5 pounds), basically half the weight of the average pair of shoes. It's mostly made from plants, for example the sole (bottom of the shoe) is made from algae. One of the reasons is to reduce eutrophication which is exessive growth of algae in water, that can be harmful for fish species.

CO2 Savings
With only 4kg of CO2 emissions per pair (Case 1), it means a drastic reduction in emissions; percentage wise it's an incredible reduction of 71.5 %.
If all new shoes could reduce their CO2 emissions with that much it would results in the following:


As seem from the graph 4 that would result in a massive CO2 reduction of 240 million tons of CO2 anually. It's important to note the future is uncertain, however we would atleast assume that with law and legislations made locally, regionally and globally the production would probably be reduced and the CO2 savings/reduction would probably be even lower. To put into perspective how much 240 million tons of CO2 really is, it's the equivalent of the global CO2 emission increase from 2016 - 2019. Therefore it's significant to be able to reduce the amount of CO2 emitted just purely from a pair of shoes. Besides, the plants applied in the pair of shoes is able to absorb a smaller percentage of the CO2 resulting in an ever further CO2 reduction.

Water and Energy Savings

In terms of the water reduction, it's more than 50 % of the recycled shoe we used as an example, and of the reasons is simply because of the weight of the shoes. The weight of Case 1 Shoes is around 50 % lighter than conventional shoes, so therefore there is atleast a reduction of 56.5 trillion liters of water, which is more than the example we presented earlier of 45.2 trillion liters of water.
In terms of energy savings, it would probably be around atleast 50 % and most likely up to 70 %. That's because the amount of energy it requires to produce a pair of synthetic shoes and leather shoes are so high (synthetic shoes: 3.5 MJ, leather shoes: 107 Mj). The amount it would require from the actual sustainable shoe is much less, since it doesn't require high temperatures to make especially when compared to virgin plastic.

Biodegrability And Other Forms of Pollution
Since the pair of shoes is nearly 100 % plantbased it further reduces the time it would to biodegrade them. This is big pro since it would lead to major reduction in harmful chemicals being released into the soil and groundwater, as well as incineration (burning of the shoes), if we imagine that the variables and behaviours do not even change. In other words even if the 5 % recycling rate didn't change (which it hopefully will) it would still lead to a much more positive impact on the environment with a degradation of only a decade or two in comparison to conventional shoes which could take up to 1000 years as mentioned previously. Moreover, there are no harmful chemicals applied since it's organically produced meaning no harm on crops, surrounding ecosystems near agriculture, no pollution of water and thereby also less for humans too.

Overall, when comparing to an actual sustainable shoe the environmental impacts reduce even further since it's nearly all from natural sustainable resources with very little recycled elemements from non-plantbased materials.

Summary

The environmental impact of the current global shoe production is very polluting in many areas such as air pollution, excessive water and energy consumption, soil and groundwater pollution, pollution of ecosystems etc. This is due to the material used to make most shoes and the fact that the recycling rate is only 5 % globally causing much harm when ending in landfills. When comparing to a pair of recycled shoes from synthetics, also in the category of 'sustainable shoes' there was a drastic reduction (50% or more) on all categories in terms of environmental impact indicators applied in this short case study.
Even further using an actual shoe from Case 1, that is nearly all made from natural sustainable ressources there was even further reduction on environmental impacts and the case for applying more shoes from natural sustainable ressources is, in our opinion based on the data, a more sustainable option. It is thought that the recycling rate will eventually increase within the next 10 years, and the production will more and more be made from recycled materials, and best case scenario from natural sustainable resources.

Sources:

EPA
Standord.edu
Assessment_of_the_Carbon_Footprint_and_VOCs_Emissions_Caused_by_the_Manufacturing_Process_of_the_Footwear_Industry
Assessing the environmental footprint of recycled plastic pellets: A life-cycle assessment perspective - Volume: 32, Environmental Technology and Innovation
Outsideonline
Onegreenplanet.org
MIT news
Unsustainable Magazine
Asparagus Magazine
Circular Online
Run Repeat

FAQs (Conventional & Sustainable Shoes)

How long have shoes been around?
Shoes have been worn for thousands of years. The oldest known shoes were found in a cave in Armenia and dated to around 5500 BC.

How long does it take for synthetic shoes to biodegrade?
Synthetic shoes containing plastics like polyester and polyurethane can take hundreds of years to biodegrade in landfills. Some estimates indicate it can be over 200-1000 years.

How long does it take for sustainable shoes made from natural materials to biodegrade?
Shoes made primarily from natural and biodegradable materials can break down much faster, often within 5 -10 years when composted.

Are sustainable shoes more durable than conventional shoes?
Sustainable shoes tend to be on par or more durable than conventional shoes. Natural materials like leather can withstand repeated use and last many seasons with proper care. Modern sustainable designs also focus on quality craftsmanship.

What is a heel lock?
A heel lock is a design feature that helps secure the heel during walking/running to prevent shoes from slipping off. It provides stability and support.

Table 1: CO2 Production Of Conventional Shoes Pr Year

Graph 1: Comparison of CO2 Production Pr Year (Conventional vs Sustainable Shoes)

Table 2: Comparison of Energy Consumption in GJ/Year (Conventional vs Sustainable Shoes)

Graph 2: Ilustrative comparison of Energy Consumption in GJ/Year (Conventional vs Sustainable Shoes)

Graph 3: Comparison of Water Consumption (Conventional vs Sustainable Shoes) Per Year

Graph 4: CO2 savings pr year when substituting all shoes with recycled (sustainable) shoes