Apple has said that it expects so-called first owners of £500 iPhones, iPads and Apple Watches to replace them after only three years of use, and Mac computers only four.

As part of the company’s new environmental push, which includes its new Apps for Earth campaign with the WWF, Apple has listed how long it expects its products to last for their “first owners” and therefore how much they contribute to the greenhouse gas lifecycle.

Within a new question and answer section Apple said: “Years of use, which are based on first owners, are assumed to be four years for OS X and tvOS devices and three years for iOS and watchOS devices.”

That assessment doesn’t take into account the recycling of devices, their reconditioning and their resale, of course, but when you buy a new iPhone 6S for £539, Apple expects it to last three years, something many suspected. Apple has been accused of intentionally slowing down iPhones every time a new one is released, although there is little evidence to support the theory.

Until recently the company only provided software support for an iPhone or iPad for around three years, typically providing two major iOS version updates from the moment they were released. The launch of iOS 8 and then iOS 9, which still supports the iPhone 4S released in October 2011, changed that.

Mac computers, however, have much longer software support lives. The latest version of Apple’s computer software OS X 10.11 El Capitan still supports computers from 2007, despite Apple expecting Mac computers to last four years.

Apple also slipped up, indicating that it could rebrand its computer operating system OS X as MacOS. The clause talking about the life expectancy of Apple computers originally said it was “assumed to be four years for MacOS and tvOS devices”, but was later changed back into line with current branding to “assumed to be four years for OS X and tvOS devices”.

The MacOS brand ceased to be used after version 9.2 in 2001, replaced by OS X 10.0 Cheetah later that year. Whether the slip up and correction indicates that Apple will switch back to its MacOS branding is unknown. The company could be running into issues with its naming, as OS X – pronounced OS 10 – is currently at version 10.11. Will it continue to use decimal places to describe its new OS versions, or will it revert back to MacOS and release an eleventh version? And will anyone care what it’s called beyond technology enthusiasts?