Greener computing: newsletters

As a member of several small clubs and societies, I (like many of my readers, I am sure) receive several newsletters every month, and as a newsletter editor myself I notice the presentation as well as the content. I see a gradual but inexorable trend towards newsletters which are both posted in hard copy via snail mail and sent via email, or have even gone all the way to online-only distribution.

As a conservationist (like many of my readers, I am sure), some of the emailed newsletters disappoint me. I’m sure their editors – well-meaning, under-appreciated folk one and all (like many of my readers, I am sure) – don’t realise that computing has a significant environmental footprint. That means, of course, that reducing the electronic size (the file size) of an emailed newsletter is worthwhile, saving carbon emissions just as an emailed newsletter saves trees and postie-bike emissions (as well as postage costs) in the first place.

How can we do it? What makes a ‘big’ file?

Saving a few test documents on your computer shows that words alone aren’t a problem. Twelve pages of text might become a 100-200 KB file – not big at all. Drop a photo into it, however, and file size explodes to perhaps 3 MB (that’s 3000 KB). Think, “Oh, a smaller photo will be okay,” and down-size the photo in Word and it will still be 3MB.

Oops! Why?

In a word, Word. By default, it saves the photo with the document at its original size, even when it shows and prints a much smaller version. If you’re foolhardy or a Word expert, you could dig down into its dialogue boxes to change that setting (look for “Compress Pictures”). Alternatively, and more reliably, you can re-size the photo before inserting it into your document. Use any basic image-editing software (Picasa is fine) and “save as” a new name so that you haven’t over-written your best-quality original.

How big does the photo need to be?

In the monthly newsletter I edit for Reef HQ Aquarium, my column is 7.6cm wide so I can simply set width=7.6cm. For an extra benefit we must look at “resolution”, which is how many pixels (dots) per inch (dpi), and save at the right width and the correct resolution. Glossy-magazine resolution is 300dpi, newspapers are more like 120dpi and computers have improved from a blurry 72dpi to around 96. More dots means a bigger file, and there’s no sense in printing anything people can’t actually see, so I have settled on 150dpi, which is better than screen resolution and just as good as the photocopier can achieve for the hard copies.

composite image at different resolutions
Reducing resolution from 300dpi to 150, 72 and (an extreme) 36dpi reduces this small picture’s file size from 140KB to 40, 16 and 12KB. The first change saves the most memory and is the least visible.

The composite image above isn’t necessarily at the stated resolutions any more although it does accurately represent the amount of change from one resolution to the next. This pdf is the same sequence of images at their original sizes.

Sending your newsletter as a Word file (.doc or .docx) can turn it into alphabet soup if the recipient’s computer doesn’t have your favourite fonts, and may even make it unreadable to anyone who hasn’t got the latest version of Word, so we should normally turn it into a pdf. In Windows, there’s one last tweak here: go to the preferences for saving pdf files and choose the “save at minimum size” option. The saving is smaller but worthwhile.

Using these strategies results in a newsletter of twelve A4 pages becoming a pdf of about 1000 – 1200 KB (1 to 1.2 MB). It would be between two and ten times that size with the same number of photos just dropped into the Word file and edited there – slower to send, slower to open, and burning up between two and ten times as much CO2 at every step for no visible benefit. Incidentally, the advantages of re-sizing your photos apply just as much to web pages: shrinking them to the right size and resolution will speed up page loading and save CO2 without any noticeable impact on the readers’ enjoyment.

A slightly different version of this article is due to appear in Waves, newsletter of the Reef HQ Volunteers Association, very shortly. Click here to download an earlier issue and see what it looks like … you might enjoy some of the articles, too.