Month / September 2017

by admin

iPhone vs Refrigerator calculations solved

Some sources say that an iPhone consumes more energy than a refrigerator.

1. Question: However, an iPhone charger only charges 5W of power it is said to be less efficient than a refrigerator (source Time), is this true?

2. Final answer

An average iPhone user uses yearly about 143kWh including data (1GB per month), whereas even the best-case scenario refrigerator uses 217 kWh per year. As long as you do not exceed too many GB per month you are not using more than a refrigerator.

3. Procedure used to obtain your answer

Finding yearly charging energy for an iPhone (Apple site, see sources)
Assuming yearly data usage for an iPhone
Finding yearly refrigerator energy costs by visiting an online retailer and choosing the most energy-efficient, manufacturer given usages. In this way you find the best-case scenario consumption values of a refrigerator. I do not use real usage values, because real values would make the difference to an iPhone energy consumption even larger, making the comparison less nice.

4. Parameters used and describe for each parameter how it was found

  • iPhone charger power = 5W
  • iPhone charging time assumption = 3 hours
  • Charging an iPhone for one year = 5.5 kWh
  • A mid-priced model refrigerator uses yearly 217 kWh (Koelkaststore.nl)
  • It is assumed that an iPhone uses 1GB per month.
  • The article of Time assumes 19 kWh per GB, while other articles state a usage of 0.1 kWh per GB (http://thebreakthrough.org/index.php/programs/economic-growth/the-bottom-line-on-iphones-vs.-refrigerators). We can take the average of about 2 kWh, which lies between these values (logarithmically).
  • This leads to a yearly usage of 2*1*12 + 5.5 = 29.5 kWh.
  • To cross-check: A virtual private server with a capacity of 2000 GB has a current of 0.07A (source CloudVPS). P = 0.07*230 = 16 W. Per month 12 kWh. This gives a way lower energy rate than 2kWh per GB, but I can imagine that some internet request may cost high energy, while wireless technologies are not included yet in this calculations.
  • To include WiFi connections, the power of a wireless router is examined, which is maximum 22W (AVM). By taking an average of 10W while the iPhone is continuously connected to that router, an extra 88 kWh can be added. Since a WiFi connections is shared over several devices most of the time, we assume that on average about 3 devices (laptops, smart TVs, telephones, etc.) simultaneously use the WiFi connection, giving an extra 29 kWh to the usage of an iPhone. This leads to a total yearly usage of 143 kWh.
  • This summarizes the impact of data usage. Even the best-case scenario (very energy-efficient and manufacturer given-data) refrigerator uses still more energy than an average iPhone user per year.

5. Discussion, including results from other sources or other estimates

The power usage of a cellular network is not included, as well as the power usage of transferring data over fibers (transmitting data over long distances may require signal enhancers, which consume energy). Although energy assumptions made are already on the exaggerated scenarios, which may substantially compensate for not included data that were too hard to obtain. It also would be better including scientific sources of usage per GB and the average data usage of mobile phone users.

6. References and/or sources.

The statement about that an iPhone uses more energy than a refrigerator is made by an article in Time (see sources): As this article says: ‘The average iPhone, according to Mills’ calculations, uses about 361 kWh a year once the wireless connections, data usage and battery charging are tallied up.’. That seems like a very high number for a single GB of data. Used sources: