Design for a circular economy: reducing the impacts of the products we use

Methodology for determining the environmental impact of smartphone production and use
Design for a circular economy: reducing the impacts of the products we use


To understand whether new ecodesign measures to extend the lifespan of smartphones would have a significant impact, analysts at PwC, who are members of the Circular Economy Task Force, assessed the environmental impact of producing a phone relative to the impact of using a phone. In particular, we were keen to understand how the average annual impact would change if phones were kept for longer and so the production impact would be split over more years. The impacts covered by this analysis are: greenhouse gas emissions, water consumption and raw material use.

The production phase includes the extraction of raw materials like metals, the processing of raw materials, the manufacture of the smartphone and the transportation between production sites and to the point of sale. The use phase impacts of a smartphone are the electricity used whilst charging as well as network and data usage and the associated impacts of these. These steps are outlined below.


Overarching assumptions
  1. The analysis represents a generic phone: data for a generic phone was used where a credible source is available; where this was not available and there were better data for a brand of phone, such as an Apple iPhone, that was used instead. The analysts had no preference for any brand of phone, but there was more existing analysis and data available for iPhones than other types of smartphone.
  2. The smartphone is assumed to be used for two years, which is the standard lifetime a phone is kept in use in most smartphone studies, and specifically in the life cycle assessment chosen here to estimate the carbon footprint. [1]
Greenhouse gases
The data points and sources used to calculate the carbon footprint of the production and use of a phone are detailed below.
Phase Footprint (kg CO2e)
Production 60 [1]
Direct use (charging) 4.875 per year [1]
Indirect use (data and networks) 1.31 kg per year [2,3,4]

The indirect use impact was calculated using an average data use of 7.2GB/month [2] which equates to 86.4GB/year. The total energy use from data centres and data transmission is 0.065kwh/GB according to the IEA [3] and so the total energy use per year is 5.6kwh. This equates to 1.31kg CO2e each year using the UK BEIS emission factor of 0.23 kgCO2e/kwh [4].

Water consumption
PwC found that a total of 12,760 litres of water (1,460l blue, 3,720 green and 7,590l grey water) are required to produce the average smartphone [5]. It is assumed that no water is used within the use phase.

Raw materials
PwC took the proportion and weight of metal elements in a smartphone from Vice (2017) [6], who summarise the research included in the book The one device: a secret history of the iPhone by Brain Merchant. This analysis just looks at the production of metal elements for a smartphone, which contribute to 60 per cent of the phone’s weight.*
 
Metal element Proportion of iPhone Weight in iPhone (g) Weight of ore to get amount in iPhone (g)
Aluminium 0.2414 31.14 155.7 [7]
Arsenic 0 0.01 N/A
Gold 0.0001 0.014 2800 [8]
Bismuth 0.0002 0.02 N/A
Cobalt 0.0511 6.59 2196.67 [9]
Chromium 0.0383 4.94 13 [10]
Copper 0.0608 7.84 980 [11]
Iron 0.1444 18.63 38.81 [12]
Gallium 0.0001 0.01 N/A
Potassium 0.0025 0.33 N/A
Lithium 0.0067 0.87 21.75 [13]
Magnesium 0.0051 0.65 N/A
Manganese 0.0023 0.29 0.83 [14]
Molybdenum 0.0002 0.02 6.67 [15]
Nickel 0.021 2.72 247.271.00 [16]
Lead 0.0003 0.04 1.00 [17]
Tin 0.0051 0.66 6.28 [18]
Tantalum 0.0002 0.02 1.29 [19]
Titanium 0.0023 0.3 N/A
Tungsten 0.0002 0.02 2.67 [20]
Vanadium 0.0003 0.04 4 [21]
Zinc 0.0054 0.69 10.62 [22]

* Please note: weights and percentages of elements will vary by phone make and model. For example, some estimates for aluminium percentages are much lower (around 14 per cent). If the other metal weights were to remain constant, this would mean a change in ore required from 6.49kg to 6.55kg.
For each metal element, a source was found to estimate the weight of ore required to produce the weight of metal required for a smartphone. Where a range was provided, the average weight was taken. This was not possible to find for all metals, but 98 per cent of the weight of metals in a smartphone have been covered. The total weight of ore required for each metal component was added up to estimate 6.5kg of ore being required to be mined through to produce the metals in a smartphone.

Calculating the annual impact of extending the use phase
The analysts added up the production and use phase impacts (greenhouse gases and water consumption) to calculate the total environmental impact across the two year lifespan of a typical smartphone. They then calculated the total impact for three, four and five years of smartphone ownership by adding the equivalent number of years’ worth of use phase impact. This was then divided by the number of years of use to understand the greenhouse gas or water footprint per year of smartphone life.

Estimating the total number of phones sold in 2019
The number of smartphones sold in the UK in 2019 was estimated from taking the number of iPhones sold in the UK (7,100,000 [23]), which account for 50 per cent of the UK market share [24] of phone sales. This means that in total, 14,200,000 phones are estimated to have been sold in 2019.

Estimating the production environmental impact of all phones sold in 2019
The water, greenhouse gas and raw material production impact was multiplied by the estimate for all phones sold in 2019 to understand the total impact of producing those phones. A comparator was then created for each of these figures by comparing the volume or mass to that of common objects. The comparators and sources are given below:
Environmental impact Comparator Source
Water 72,477 Olympic sized swimming pools Volume of water in Olympic sized pool [25]
Greenhouse gases 664,132 cars driven for 1 year Average kgCO2e emitted per km travelled by an average car registered in 2015 in the UK [26]
Average miles travelled by a car in the UK per year [27]
Raw materials 7,081 London double decker buses Weight of London double decker bus [28]
 
Evaluating the impact of poor enforcement of existing standards
The calculations for the unnecessary UK emissions that result from products that do not comply with minimum standards are based on the assumption that the UK, like European member states, is missing out on 10 per cent of emission savings that should be expected. [29] The figure of 800,000 tonnes of unnecessary emissions was then converted the number of average cars on the road using the same comparators used for the analysis of phones’ impacts [26, 27] to reach the figure of the unnecessary emissions equalling those from 623,599 average cars.

Evaluating different products receiving the same energy efficiency rating
To analyse the differences in energy consumption between products under the same energy efficiency rating, Green Alliance staff researched appliances available to buy from the UK’s largest electricals retailer by market share. [30] We looked at washing machines, fridges and televisions, as examples of common household appliances.

Products from the highest available energy efficiency rating for each appliance were included in the analysis. For washing machines, the highest rating was A+++, for which there were 175 products available for purchase. The most energy efficient fridges, of which there were nine products on sale, were also rated A+++, whereas the highest energy efficiency rating for televisions was A+, with 123 products listed on the website. At the time of data collection, there was one A++ labelled television for sale, but given the comparative nature of our analysis, we chose to look at the A+ class, where the sample size was much greater.

For each product, information on energy efficiency rating, retail price, annual energy consumption (kWh) and size (load capacity (kg) for washing machines; storage capacity (litres) for fridges; and screen sizes (inches) for televisions), was collected. All product information was collected in September 2020, and for products where a discounted sale price was listed on the website, the original full price was recorded. Annual energy consumption was converted to annual running costs to present a more consumer-relevant value, based on a conversion using the average electricity cost of 14.37p/kWh. [31]

For our analysis in the main report, the products with the highest and lowest annual energy consumption (measured in kWh) within each appliance category were then selected for comparison. This was designed to illustrate the significant differences in annual energy consumption between appliances labelled with the same energy efficiency rating. We also carried out some additional analyses to assess whether such variation was observed even when controlling for size variation within energy efficiency ratings. For TVs and washing machines, where a higher sample number allowed such an exercise, we found that even within size groups, there was often large variation between the highest and lowest energy using products.
 
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