The iPhone 4s, with its iconic 'boxy' design, influenced the recent iPhone 12 and marked the end of Steve Jobs' leadership. An energy analysis revealed significant production and transport energy, 230 MJ and 26 MJ respectively, largely driven by components like the Logic board. Energy from phone usage over itrs lifetime varied, with light users consuming 23 MJ and heavy users 62 MJ, while data and WiFi usage unexpectedly contributed 1093 MJ over the product's lifetime. These findings emphasize the importance of sustainability in smartphone design and usage.

Production Energy Consumption

The production phase of the iPhone 4S involves a significant amount of embodied energy. The logic board, battery, and casing are the primary contributors to this energy, with values of 200 MJ, 22 MJ, and 4 MJ respectively. These values are derived from data sources including Granta Edupack and other industry-specific databases.

In addition to the materials, the transport of the iPhone 4S also contributes to its embodied energy. Given the global distribution of Apple’s suppliers and factories, the transport energy was estimated to be 26 MJ considering the energy consumed during the transportation of raw materials and finished products, highlighting the environmental impact of global supply chains. Moreover, the iPhone 4S was assembled by Taiwan-based contract manufacturers Pegatron and Hon Hai Precision Industry, also known under the Western moniker Foxconn and would have used novel advanced manufacturing techniques that would likely not have been optimized for energy efficiency in their infancy.

Energy during Phone Usage

The energy consumption of the iPhone 4S during its use phase is highly dependent on the usage patterns, charging habits, and data usage of the user. Three scenarios are considered: light use, heavy use, and one charge a day. It was calculated that where light usage would contribute 22MJ to the phones overall embodied energy, heavy usage would contribute almost triple this at 62MJ. The iPhone 4S battery has a capacity of 1432mAh. The energy consumption can vary significantly depending on not only screen time, but how the phone is used. For example, streaming video can consume a lot of energy, while simply sending text messages will use much less.

The Hidden Impact of Data

Data usage is the largest factor in the energy consumption during the use phase of the iPhone 4S. Over the product lifetime, data usage can contribute up to 1093 MJ of energy which is far greater than the energy from production or from changing the device. This highlights the hidden impact of data on the energy footprint of smartphones. In fact, transferring data via 3G mobile networks was found to consume more energy than with WiFi networks. Per transferred gigabyte (Gb), the energy consumption in a WiFi network was 0.06kWh and for 3G networks around 2.9kWh.

The combined embodied energy in MJ can be broken down in Table 1, showing the sizeable impact of data consumption on smartphones.

Importance of Recycling

The end-of-life phase of the iPhone 4S presents an opportunity for energy saving through recycling, especially for the lithium-ion battery, which has a high ecological footprint. Recycling the battery can save 36.1% of its embodied energy. Recycling old smartphones reduces the need to produce new ones, helps conserve energy, and mitigates greenhouse gas emissions. Moreover, it also plays a crucial role in handling toxic materials and creating employment opportunities in the recycling industry.