Updated Wed 30 Dec 2020


Reduce total energy use by myself and clients

My largest energy use is the web servers that run client websites 24 hours a day. I:

I work from home, so that removes the environmental impact of having a separate office and reduces travel.

Use renewable energy, carbon offset any that isn't

Office/Domestic electricity

100% renewable electricity since 2011 – supplier Ecotricity

14% renewable gas as of May 2019, the rest offset (2018: 12%, March 2017: 5%): Ecotricity have an anaerobic digester site approved, but they still haven't built it

Web servers and cloud services

Only part of this is green energy and it's very complicated to calculate how much. Although I did find a datacenter that is currently using 100% green electricity (Bytemark; their supplier is Total Gas and Power - who use - to the best of my knowledge - RECs, but don't generate their own renewables), I have elected to stick with Linode/Telecity and offset my small carbon footprint for webservers multiple times over.

Carbon Offsetting

As the figures have so many caveats and I'm using relatively little energy for business work (~ 0.25 tonnes CO2 annually for webservers), I've decided it's much simpler to just offset (a greater amount) at regular intervals:

  • offsetting remains very cost-effective and you can do it a little at a time
  • it helps covers non-business (domestic) energy usage - which is much higher due to heating etc.
  • it helps compensate for usage of less efficient equipment in previous years
  • the conservation projects you can support have intrinsic value


  • Apr 2016: 5 tonnes of CO2 offset (or approx 0.75 acres of protected land) via World Land Trust Carbon Balanced Programme
  • Aug 2018: 1000 m2 protected Mexican Forest land via World Land Trust appeal
  • Dec 2020: 3 tonnes of CO2 offset via World Land Trust Carbon Balanced Programme
  • May 2016 to Dec 2020 (ongoing): monthly donation to Trees for Cities (each roughly the equivalent of sponsoring a large canopy tree on a city street or several small trees in a park)

Why these charities?

Both the World Land Trust and Trees for Cities are UK based, established in 1989 and 1993 respectively. Their staffing levels are modest and they don't use aggressive fundraising tactics.

World Land Trust assists overseas NGOs in purchasing land (over 500,000 acres so far) for small-scale sustainable development. Rather than save specific species, controlling the land means the whole ecosystem is protected. Its patrons are David Gower, Chris Packham and Sir David Attenborough.

Trees for Cities has projects around the UK, especially in London. They combine tree-planting with education and community work. It's supported by Jon Snow, Alistair McGowan and others.

(I do not support activism, marches, protests, vandalism, so-called "direct action" etc.)

Estimating datacentre carbon footprint

TL;DR: My datacentre energy usage is low and I carbon-offset a far higher amount, but it's very hard to calculate precise usage due to lack of public information.

Most of my webservers are hosted by Linode, at Equinix Telecity's Powergate datacentre in Acton, West London.

All direct datacentre customers (i.e. those who leasing cages or racks from the datacentre operator) are billed on multiple criteria including power usage in amps. So it's in Linode's interests to keep consumption as low as possible, by selecting modern, power efficient components. They don't reveal details of all their exact hardware (this is quite common), but they are using Intel® Xeon® E5-2680v3 processors - these are very new - the CPU in a server is usually by far the biggest power drain (except for a spike when you first switch it on.)

Linode also only use SSDs, which (generally) have lower power consumption than spinning disks. They use DDR4 RAM, which is roughly 30% more power efficient than DDR3, running at a slightly lower voltage.

The datacentre is certified to ISO 50001 and its very energy efficient (a PUE of 1.35 with a modern cooling system, waste heat used to heat office space, rainwater harvesting, motion-activated lighting and Carbon Trust Standard certification.) Datacentres use around 2.5% of European electricity, so a lot of work is going into energy efficient design.

However, currently only 20-25% the data centre's electricity comes from renewable sources.

In 2015, Greenpeace Click Clean report gave Telecity a mix of C/D grades. By the next report in 2017, this had improved to B (now listed under Equinix, who acquired Telecity in Jan 2016). (Last checked December 2020.)

I also use Amazon Web Services: specifically their S3 and Route 53 products, for backups, DNS and some web hosting of media/assets.

Percentage of Amazon Web Services energy from renewables (based on published sustainability data):

Apr 201525%
Dec 201640%
Jan 201850%
2025100% target (as of Dec 2020)

My AWS usage is much lower than for the VPSs, as it's mostly data storage and low intensity work like responding to DNS queries. I also use AWS Glacier – its designed for infrequently accessed files – Amazon remain very secretive about how Glacier works, but the technology we think they're using is almost certain to need less energy.

As you can see, it's impossible to calculate an accurate carbon footprint when so many companies are involved and so much of it isn't in the public domain.

Occasionally they do provide information. For example, I use Gmail, and Google have calculated the average power consumption per Gmail user is 2.2 kWh per year.

Back-of-an-envelope carbon footprint calculation:

Based on info from Linode's CEO (these are 2008 figures based on US voltages!) a particular size of VPS uses about 7.5 watts, or 65 kWh a year, which is roughly 0.03 tonnes of CO2 (using the average UK grid energy mix).

This would mean the servers I'm responsible for generate about 0.25 tonnes a year.

However, this doesn't include all the other infrastructure, e.g. air-cooling, the use of the backup server, the data centre building, the fuel in the backup generators etc. or the energy used in equipment manufacture and datacentre construction.

Reuse and Recycle

Tips for choosing equipment: maximise lifetime and energy efficiency

My desktop computer is a 2012 Apple Mac Mini I purchased November 2012. Apple describe this as "the world's most energy-efficient desktop computer", although you should remember it doesn't include a display (see below). A priority for me was something that used minimal energy when in standby (1.25W) but can wake up instantly when needed, without having to reopen applications or restart virtual machines.

You also want a computer that will last a good number of years – 67% of the greenhouse gas emissions for the Mac Mini (290kg or 0.29 tonnes of CO2) are from manufacture and shipping, and that's assuming a full four years of ownership (it has now lasted 12).

The Mac Mini has some environmental and practical advantages over other Apple products:

I bought the highest specification available at the time Apple refreshed the product line, with the view to using it for as long as possible (I'm hoping until at least 2018/2019 2020 2021/2022). The only constraint so far has been disk space - in 2018 the internal hard drive failed and I took the opportunity to purchase a 2GB (twice as big) external SSD instead. The software can no longer be upgraded beyond macOS Catalina (10.15) and therefore it won't have an indefinite lifetime due to eventual lack of security updates.

For anyone looking to buy a new Mac in late 2020, I would recommend the new Mac Mini with the new M1 chip - which is both faster and more energy efficient - but be aware it is limited to 16GB RAM and a reduced number of USB ports.

Besides anything else, upgrading a computer is time-consuming: there's the decision fatigue in choosing a new device and, despite migration tools, a lot of software inevitably needs to be reconfigured. You're also forced onto the most recent version of the operating system, which may be buggier than you'd like, and nowadays operating system upgrades (including MacOS) typically deliver only marginal benefits; most of the features you need have already been added. The value generally comes from updates to third party software which is usually supported by previous OS versions.

The Dell display meets various environmental certifications including EPEAT Gold. I can often use it comfortably use it with the brightness on one of the lowest settings (there's an energy gauge built in) and my measurements show in that situation it's using less than 10 watts. Would recommend, though occasionally I wish I'd chosen a larger one (not that often though). I don't feel I've especially lost out in any way by not having a retina display - HD video at 24" is still very sharp. Having a separate display rather than an iMac also makes it easier to adjust the height / exact position.

I use USB-powered WD My Passport drives for backups, these automatically spin down when not in use.

Since 2015 I've not bought any new spinning disks, all HDDs have been are solid state (SSD), to increase speed, provide equal or longer MTBF (failure on a SSD is typically through gradual reduction in available disk space as blocks fail, rather than catastrophic as with a spinning drive) and to reduce energy use (no moving parts).

Carbon footprint for business travel and shipping

Personal travel (not listed) is usually greater, but doesn't include any flights.

Year Approx CO2 tonnes Business travel methods
2015 0.01 train, underground
2016 0.01 train, underground
2017 0.07 train, underground
2018 0.01 train, underground, taxi
2019 (to 27 June) 0.084 train, underground, taxi
2020 0.005 train (most meetings online due to pandemic)

(Very) occasionally I need to send packages.

DPD (who are my current preferred choice) carbon offset all their emissions.

UPS and others have introduced carbon neutral shipping at an extra price.

Since Autumn 2020, you can have packets/parcels collected by Royal Mail during deliveries, which saves a trip to drop things at the post office.