Category Archives: Environment

Carbon emissions analysis of GUADEC 2022

I’ve just finished estimating the carbon emissions from GUADEC 2022, and have a few interesting highlights from the report. The report is based on data collected from the streaming servers, registration data, and the post-conference survey.

  • Having an online component to the conference increased the audience by a factor of 10: there were around 120 in-person attendees in Mexico, but there were an average of 1300 people using Big Blue Button.
  • The carbon emissions from providing the remote infrastructure were around 2.8tCO2e, or about 2kgCO2e per remote attendee.
  • Having a remote attendance party in Berlin allowed around one tenth of the attendees to attend with a factor of 10 lower transport emissions than those who attended in-person in Mexico. The average transport emissions for those who went to Berlin were 88kgCO2e, whereas they were around 1tCO2e for those going to Mexico.
  • For context, the annual emissions per person can be at most 2.3tCO2e by 2030 in order to limit global warming to 1.5C by the end of the century. That covers all food, travel, heating, purchases, etc. So travel to Mexico was 40% of the average attendee’s annual target.
  • Half of the in-person attendees travelled from within Mexico, which will have skewed the mean transport emissions downwards. The distribution is more likely bimodal between around 50kgCO2e for locals and more like 2-3tCO2e for those coming from outside Mexico.
  • As I wrote at the time, the remote attendance party was fun to attend and felt like it worked as a way to attend the conference (there were no A/V problems, we had some nice local socials, etc.). I would do it again.
  • The post-conference survey had a low response rate of about 19% of registered attendees, which made some of this analysis hard. Please always fill in the post-conference survey! It doesn’t take long, and aside from any of this analysis, it helps the organisers plan conferences better in future.
  • Many thanks to Kristi, Caroline and Bartłomiej for collecting the data needed for this analysis.
  • If anyone spots problems in the analysis please say! This is not the kind of thing I practice doing very often and I’ve had to make a number of assumptions.

Other conferences

A post-conference survey has been done for other big GNOME events, such as GNOME.Asia and LAS. Would anyone be interested in doing a similar analysis for those events? Perhaps we can get a semi-automated pipeline in place for it.

Getting from the UK to Riga for GUADEC 2023

I’ve just booked travel for getting to Riga, Latvia for GUADEC 2023, and I thought I’d quickly write up my travel plans in case it saves someone else some time in planning travel.

I am not flying, because planes are too polluting. Instead, I am taking the train to Lübeck in Germany, then an overnight ferry to Liepāja, and then a bus the following morning to Riga. It’s a bit slower, but means it’s a bit easier to get some hacking done, stretch my legs and move around, and not fund fossil fuel companies as much. I’ll get enough stopover time in Köln, Hamburg and Lübeck to quickly look round, and a night in Liepāja to see it.

Overall the travel time is just over 2 days, with half of that spent on trains, and half on a ferry. By comparison, a flight is about 7 hours (5 hours flying, 2 hours faffing in airports) plus travel time to the airport.

The carbon emissions (140kgCO2e return) are roughly a quarter of those from flying (520kgCO2e), and interestingly a significant part of those emissions (46kgCO2e) is the 3 hour bus journey to get from Liepāja to Riga, though that’s quite sensitive to the occupancy level of the bus.

The financial cost (£800 return) is about two times that of flying (£380), though I have not factored in the costs of getting to/from airports and have not fully explored the hidden fees for baggage and other essentials so the ratio might be a little lower. This is quite upsetting. A disproportionate part of the cost (£178 return) is the Eurostar, because it’s oversubscribed and I missed the early ticket releases due to waiting for grant approval. Perhaps I should not wait next time.

The journey

On 2023-07-22:

  • Eurostar from London to Brussels-Midi, departing 07:04
  • Train from Brussels-Midi to Lübeck-Travemünde Skandinavienkai, departing 10:25 (ICE 15, ICE 200, RE 11428, RB 11528)
  • Nice walk from there to the ferry terminal for half an hour
  • Overnight ferry from Lübeck/Travemünde to Liepāja, departing 23:30

On 2023-07-23: On the ferry all day, then stay overnight in Liepāja

On 2023-07-24: Bus from Liepāja to Riga, departing early morning


I strongly looked at taking the train from Hamburg to Stockholm, and then the ferry from there to Ventspils. Unfortunately, it has limited capacity and there is track maintenance planned for around my travel dates, so I could not get suitable tickets. It would have made the timings a little more convenient overall, for about the same overall carbon emissions and cost.

Join me

If anybody else is going overland from the UK or far-western Europe, this is hopefully a sensible route for you to take, and it would be lovely if you wanted to join me. I will be arriving 2 days early for GUADEC (as we’re having an Endless OS Foundation meetup), but if you wanted to do the same journey 1 or 2 days later then it shouldn’t differ significantly. In any case, I can put you in touch with others making this journey if you want.

Garden work

Another post which is not about software! I’ve recently, finally, finished reworking my garden, and here’s a brief writeup of what happened. It includes some ideas for low-embodied energy and ecologically friendly garden design.

The original garden

This house is on a hill. The original garden was a set of three concrete slabbed terraces going down the hill, with some wooden decking on the top terrace. There was a block paved path ramping down the garden, separating the decking from a sloping grass lawn. There were very few plants which weren’t grass or a few pots.

Problems with this included:

  • Decking was rotten
  • Lower terrace served no purpose and was devoid of life
  • There was very little biodiversity in the garden, and no space to grow anything
  • Steps in the path had been installed with uneven heights and that was surprisingly annoying

The plan

  • Get rid of the decking because it’s rotten
  • Remove the terraces because they’re just concrete, and replace them with more soil and planting area
  • Make the subdivisions of the garden less rectilinear so it feels a bit less brutal
  • Lower some areas of the terraces a bit to get a bit more privacy (the garden is overlooked)
  • Severely reduce the grass lawn area, because it requires frequent mowing and is not very ecologically diverse
  • Rebuild the path to make it curvy and add some planting area in a sunny spot by it
  • Keep the garden adaptable and don’t make anything too permanent (by cementing it in place) — I, or others, may want to rearrange things in future

Executing the plan

I started on this in 2019. Progress was slow at first, because a large part of the plan involved digging out the terraces, and there was some question about whether this would undermine the foundations of the house. That could cause the house to fall down. That would be bad.

I talked to a structural engineer, and he specified a retaining wall system I could install, which would retain the house wall and foundations, act as a raised bed, and is made out of wood so would have low embodied carbon compared to a (more standard) masonry wall (which is about 40kgCO2e/m2, see table 11 here). There was various other research and considerations about adjoining property, safety, drainage, appearance of the materials as they age, and suitability for DIY which fed into this decision. I can go into the details if anyone’s interested (get in touch if so).

What followed was about 10 months of intermittent work on it, removing the old terraces, digging a pond and sowing some wildflowers, installing the new retaining wall, fixing drainage through the clay, bringing in soil, laying a clover lawn, and rebuilding the path.

The result

I’m pretty pleased with the result. There are a few decisions in particular which I’m quite pleased worked out, as they’re not a common approach in the UK and were a bit of a gamble:

  • Clover patio. Rather than a paved patio area (as is common here), I planted clover seed on a thin bed of soil with a weed control membrane beneath. This has a significantly lower embodied carbon than paving (around 100-200kgCO2e/tonne less, if imported natural stone was used, which is the standard in the UK at the moment), and drains better, so it doesn’t contribute to flash flooding runoff. With rain becoming less frequent but more intense in the UK, runoff is going to become more of a problem. My full analysis of the options is here. I chose clover for the planting because it doesn’t require mowing, and should stay short enough to sit on. As per table 1 of this paper, I might adjust the planting in future to include other non-grass species.
  • Wooden retaining wall. I used Woodblocx, and it worked out great. It didn’t require any cementatious materials (which have high embodied carbon), just a compacted type 2 sub-base and their wooden blocks. It’s repairable, and recyclable at end of life (in about 25 years).
  • Wood chip path. This was easy to install (wood chips over a weed control membrane), doesn’t contribute to flash flooding runoff like paved paths do, and is a good environment for various insects which like damp and dark places. It will need topping up with more wood chips every few years, but no other maintenance. The path edging is made from some of the old decking planks from the original garden (the ones which weren’t rotten).
  • Water butt stands. These are all made from bits of old decking or Woodblocx offcuts, and make the water butts easier to use by bringing the tap to a more reachable level. I also made a workbench out of old decking planks.

Subjectively, now the garden’s been basically finished for a year (I finished the final few bits of it the other day), I’ve seen more insects living in it, and birds feeding on them, than I did before. Yay!

Mini-GUADEC 2022 Berlin: retrospective

I’m really pleased with how the mini-GUADEC in Berlin turned out. We had a really productive conference, with various collaborations speeding up progress on Files, display colour handling, Shell, adaptive apps, and a host of other things. We watched and gave talks, and that seemed to work really well. The conference ran from 15:00 to 22:00 in Berlin time, and breaks in the schedule matched when people got hungry in Berlin, so I’d say the timings worked nicely. It helped to be in a city where things are open late.

c-base provided us with a cool inside space, a nice outdoor seating area next to the river, reliable internet, quality A/V equipment and support for using it, and a big beamer for watching talks. They also had a bar open later in the day, and there were several food options nearby.

At least from our end, GUADEC 2022 managed to be an effective hybrid conference. Hopefully people in Guadalajara had a similarly good experience?

Tobias and I spent a productive half a day working through a load of UI papercuts in GNOME Software, closing a number of open issues, including some where we’d failed to make progress for months. The benefits of in-person discussion!

Sadly despite organising the mini-GUADEC, Sonny couldn’t join us due to catching COVID. So far it looks like others avoided getting ill.


Allan wrote up how he got to Berlin, for general reference and posterity, so I should do the same.

I took the train from north-west England to London one evening and stayed the night with friends in London. This would normally have worked fine, but that was the second-hottest day of the heatwave, and the UK’s rails aren’t designed for air temperatures above 30°C. So the train was 2.5 hours delayed. Thankfully I had time in the plan to accommodate this.

The following morning, I took the 09:01 Eurostar to Brussels, and then an ICE at 14:25 to Berlin (via Köln). This worked well — rails on the continent are designed for higher temperatures than those in the UK.

The journey was the same in reverse, leaving Berlin at 08:34 in time for a 18:52 Eurostar. It should have been possible to then get the last train from London to the north-west of England on the same day, but in the end I changed plans and visited friends near London for the weekend.

I took 2 litres of water with me each way, and grabbed some food beforehand and at Köln, rather than trying to get food on the train. This worked well.

Within Berlin, I used a single 9EUR monatskarte for all travel. This is an amazing policy by the German government, and subjectively it seemed like it was being widely used. It would be interesting to see how it has affected car usage vs public transport usage over several months.


Overall, I estimate the return train trip to Berlin emitted 52kgCO2e, compared to 2610kgCO2e from flying Manchester to Guadalajara (via Houston). That’s an impact 50× lower. 52kgCO2e is about the same emissions as 2 weeks of a vegetarian diet; 2610kgCO2e is about the same as an entire year of eating a meat-heavy diet.

(Train emissions calculated one-way as 14.8kgCO2e to London, 4.3kgCO2e to Brussels, 6.5kgCO2e to Berlin.)

Tobias gave an impactful talk on climate action, and one of his key points was that significant change can now only happen as a result of government policy changes. Individual consumer choices can’t easily bring about the systemic change needed to prevent new oil and coal extraction, trigger modal shift in transport use, or rethink land allocation to provide sufficient food while allowing rewilding.

That’s very true. One of the exceptions, though, is flying: the choices each of the ~20 people at mini-GUADEC made resulted in not emitting up to 50 tonnes of CO2e in flights. That’s because flights each have a significant emissions cost, and are largely avoidable. (Doing emissions calculations for counterfactuals is a slippery business, but hopefully the 50 tonne figure is illustrative even if it can’t be precise.)

So it’s pretty excellent that the GNOME community supports satellite conferences, and I strongly hope this is something which we can continue to do for our big conferences in future.


After the conference, I had a few days in Berlin. On the recommendation of Zeeshan, I spent a day in the Berlin technical museum, and another day exploring several of the palaces at Potsdam.

It’s easy to spend an entire day at the technical museum. One of the train sheds was closed while I was there, which is a shame, but at least that freed up a few hours which I could spend looking at the printing and the jewellery making exhibits.

One of the nice things about the technical museum is that their displays of old machinery are largely functional: they regularly run demonstrations of entire paper making processes or linotype printing using the original machinery. In most other technical museums I’ve been to, the functioning equipment is limited to a steam engine or two and everything else is a static display.

The palaces in Potsdam were impressive, and look like a maintenance nightmare. In particular, the Grotto Hall in the Neues Palais was one of the most fantastical rooms I’ve ever seen. It’s quite a ridiculous display of wealth from the 18th century. The whole of Sanssouci Park made another nice day out, though taking a picnic would have been a good idea.


Thanks again to everyone who organised GUADEC in Guadalajara, Sonny and Tobias for organising the mini-GUADEC, the people at c-base for hosting us and providing A/V support, and the GNOME Foundation for sponsoring several of us to go to mini-GUADEC.

Sponsored by GNOME Foundation

How your organisation’s travel policy can impact the environment

Following on from updating our equipment policy, we’ve recently also updated our travel policy at the Endless OS Foundation. A major part of this update was to introduce consideration of carbon emissions into the decision making for when and how to travel. I’d like to share what we came up with, as it should be broadly applicable to many other technology organisations, and I’m quite excited that people across the foundation worked to make these changes happen.

Why is this important?

For a technology company or organisation, travel is likely to be the first or second largest cause of emissions from the organisation. The obvious example in free software circles is the emissions from taking a flight to go to a conference, but actually in many cases the annual emissions from commuting to an office by car are comparable. Both can be reduced through an organisation’s policies.

In Endless’ case, the company is almost entirely remote and so commuting is not a significant cause of emissions. Pre-pandemic, air travel caused a bit under a third of the organisation’s emissions. So if there are things we can do to reduce our organisation’s air travel, that would make a significant difference to our overall emissions.

On an individual level, one return transatlantic flight (1.6tCO2e, which is 1.6 tonnes of carbon dioxide equivalent, the unit of global warming potential) is more than half of someone’s annual target footprint which is 2.8tCO2e for 2030. So not taking a flight is one of the most impactful single actions you can take.

Similarly, commuting 10 miles a day by petrol car, for 227 working days per year, causes annual emissions of about 0.55tCO2e, which is also a significant proportion of a personal footprint when the aim is to limit global warming to 1.5°C. An organisation’s policies and incentives can impact people’s commuting decisions.

Once the emissions from a journey have been made, they can’t be un-made anywhere near as easily or quickly. Reducing carbon emissions now is more impactful than reducing them later.

How did we change the policy?

Previously, Endless’ travel policy was almost entirely focused around minimising financial cost by only allowing employees to choose the cheapest option for a particular travel plan. It had detailed sections on how to minimise cost for flights and private car use, and didn’t really consider other modes of transport.

In the updated policy, financial cost is still a big consideration, but it’s balanced against environmental cost. I’ve included some excerpts from the policy at the bottom of this post, which could be used as the basis for updating your policy.

Due to COVID, not much travel has happened since putting the policy in place, so I can’t share any comparisons of cost and environmental impact before and after applying the policy. The intention is that reducing the number of journeys made will balance slightly increased costs for taking lower-carbon transport modes on other journeys.

The main changes we made to it are:

  • Organise the policy so that it’s written in decision making order: sections cover necessity of travel, then travel planning and approval, then accommodation, then expenses.
  • Critically, the first step in the decision making process is “do you need to travel and what are the alternatives?”. If it’s decided that travel is needed, the next step is to look at how that trip could be combined with other useful activities (meetings or holiday) to amortise the impact of the travel.
  • We give an explicit priority order of modes of travel to choose:
    1. Rail (most preferred)
    2. Shared ground transport (coach/bus, shared taxi)
    3. Private ground transport (taxi, car rental, use of own vehicle)
    4. Air (least preferable)
  • And, following that, a series of rules for how to choose the mode of transport, which gives some guidance about how to balance environmental and financial cost (and other factors):

You should explore travel options in that order, only moving to the next option if any of the following conditions are true:

  • No such option exists for the journey in question
    • e.g. there is no rail/ground link between London and San Francisco
  • This mode of travel, or the duration of time spent traveling via such means, is regarded as unsafe or excessively uncomfortable at that location
    • For example, buses/coaches are considered to be uncomfortable or unsafe in certain countries/regions.
  • The journey is over 6 hours, and the following option reduces the journey time by 2× (or more)
    • We have a duty to protect company time, so you may (e.g.) opt for flying in cases where the travel time is significantly reduced.
    • Even if there is the opportunity for significant time savings, you are encouraged to consider the possibility of working while on the train, even if it works out to be a longer journey.
  • The cost is considered unreasonably/unexpectedly high, but the following option brings expenses within usual norms
    • The regular pricing of the mode of transport can be considered against the distance traveled. If disproportionately high, move onto other options.

In summary, we prefer rail and ground transportation to favor low-emissions, even if they are not the cheapest options. However, we also consider efficient use of company time, comfort, safety, and protecting ourselves from unreasonably high expenditure. You should explore all these options and considerations and discuss with your manager to make the final decision.

Your turn

I’d be interested to know whether others have similar travel policies, or have better or different ideas — or if you make changes to your travel policy as a result of reading this.

Policy excerpt

Insulating a suspended timber floor

In a departure from my normal blogging, this post is going to be about how I’ve retrofitted insulation to some of the flooring in my house and improved its airtightness. This has resulted in a noticeable increase in room temperature during the cold months.

Setting the scene

The kitchen floor in my house is a suspended timber floor, built over a 0.9m tall sealed cavity (concrete skim floor, brick walls on four sides, air bricks). This design is due to the fact the kitchen is an extension to the original house, and it’s built on the down-slope of a hill.

The extension was built around 1984, shortly before the UK building regulations changed to (basically) require insulation. This meant that the floor was literally some thin laminate flooring, a 5mm underlay sheet for that, 22mm of chipboard, and then a ventilated air cavity at outside temperature (which, in winter, is about 4°C).

In addition to that, there were 10mm gaps around the edge of the chipboard, connecting the outside air directly with the air in the kitchen. The kitchen is 3×5m, so that gives an air gap of around 0.16m². That’s equivalent to leaving a window open all year round. The room has been this way for about 36 years! The UK needs a better solution for ongoing improvement and retrofit of buildings.

I established all this initial information fairly easily by taking the kickboards off the kitchen units and looking into the corners of the room; and by drilling a 10mm hole through the floor and threading a small camera (borescope) into the cavity beneath.

Making a plan

The fact that the cavity was 0.9m high and in good structural shape meant that adding insulation from beneath was a fairly straightforward choice. Another option (which would have been the only option if the cavity was shallower) would have been to remove the kitchen units, take up all the floorboards, and insulate from above. That would have been a lot more disruptive and labour intensive. Interestingly, the previous owners of the house had a whole new kitchen put in, and didn’t bother (or weren’t advised) to add insulation at the same time. A very wasted opportunity.

I cut an access hatch in one of the floorboards, spanning between two joists, and scuttled into the cavity to measure things more accurately and check the state of things.

Under-floor cavity before work began (but after a bit of cleaning)

The joists are 145×45mm, which gives an obvious 145mm depth of insulation which can be added. Is that enough? Time for some calculations.

I chose several potential insulation materials, then calculated the embodied carbon cost of insulating the floor with them, the embodied financial cost of them, and the net carbon and financial costs of heating the house with them in place (over 25 years). I made a number of assumptions, documented in the workings spreadsheet, largely due to the lack of EPDs for different components. Here are the results:

Heating scenarioInsulation assemblyU-value of floor assembly (W/m2K)Energy loss to floor (W)Net cost over 25 years (£)Net carbon cost over 25 years (kgCO2e)
Current gas tariff
(3.68p/kWh, 0.22kgCO2e/kWh)
Current floor2.60382308017980
Thermojute 160mm0.22327301700
Thermoflex 160mm0.21308601450
Thermojute 300mm0.121810201190
Thermoflex 240mm0.1117910820
Mineral wool 160mm0.24355401680
ASHP estimate
(13.60p/kWh, 0.01kgCO2e/kWh)
Current floor(as above)(as above)113701140
Thermojute 160mm1420290
Thermoflex 160mm1520110
Thermojute 300mm1410410
Thermoflex 240mm128080
Mineral wool 160mm1290150
Average future estimate (hydrogen grid)
(8.40p/kWh, 0.30kgCO2e/kWh)
Current floor702025090
Thermojute 160mm10602290
Thermoflex 160mm11702010
Thermojute 300mm12001520
Thermoflex 240mm10901140
Mineral wool 160mm8902320
Costings for different floor assemblies; see the spreadsheet for full details

In retrospect, I should also have considered multi-layer insulation options, such as a 20mm layer of closed-cell foam beneath the chipboard, and a 140mm layer of vapour-open insulation below that. More on that below.

In the end, I went with 160mm of Thermojute, packed between the joists and held in place with a windproof membrane stapled to the underside of the joists. This has a theoretical U-value of 0.22W/m2K and hence an energy loss of 32W over the floor area. Over 25 years, with a new air source heat pump (which I don’t have, but it’s a likelihood soon), the net carbon cost of this floor (embodied carbon + heating loss through the floor) should be at most 290kgCO2e, of which around 190kgCO2e is the embodied cost of the insulation. Without changing the heating system it would be around 1700kgCO2e.

The embodied cost of the insulation is an upper bound: I couldn’t find an embodied carbon cost for Thermojute, but its Naturplus certification puts an upper bound on what’s allowed. It’s likely that the actual embodied cost is lower, as the jute is recycled in a fairly simple process.

Three things swung the decision: the availability of Thermojute over Thermoflex, the joist loading limiting the depth of insulation I could install, and the ease of not having to support insulation installed below the depth of the joists.

This means that the theoretical performance of the floor is not Passivhaus standard (around 0.10–0.15W/m2K), although this is partially mitigated by the fact that the kitchen is not a core part of the house, and is separated from it by a cavity wall and some tight doors, which means it should not be a significant heat sink for the rest of the house when insulated. It’s also regularly heated by me cooking things.

Hopefully the attention to detail when installing the insulation, and the careful tracing of airtightness and windtightness barriers through the design should keep the practical performance of the floor high. The windtightness barrier is to prevent wind-washing of the insulation from below. The airtightness barrier is to prevent warm, moisture-laden air from the kitchen escaping into the insulation and building structure (particularly, joists), condensing there (as they’re now colder due to the increased insulation) and causing damp problems. An airtightness barrier also prevents convective cooling around the floor area, and reduces air movement which, even if warm, increases our perception of cooling.

I did not consider thermal bridging through the joists. Perhaps I should have done?

Insulation installation

Installation was done over a number of days and evenings, sped up by the fact the UK was in lockdown at the time and there was little else to do.

Cross sections of the insulation details

The first step in installation was to check the blockwork around each joist end and seal that off to reduce draughts from the wall cavity into the insulation. Thankfully, the blockwork was in good condition so no work was necessary.

The next step was to add an airtightness seal around all pipe penetrations through the chipboard, as the chipboard was to form the airtightness barrier for the kitchen. This was done with Extoseal Magov tape.

Sealing pipe penetrations through the chipboard floor using Extoseal Magov.

The next step in installation was to tape the windproof membrane to the underside edge of the chipboard, to separate the end of the insulation from the wall. This ended up being surprisingly quick once I’d made a cutting template.

The next step was to wedge the insulation batts in the gap between each pair of joists. This was done in several layers with offset overlaps. Each batt was slightly wider than the gap between joists, so could easily be held in place with friction. This arrangement shouldn’t be prone to gaps forming in the insulation as the joists expand and contract slightly over time.

One of the positives of using jute-based insulation is that it smells of coffee and sugar (which is what the bags which the jute fibres came from were originally used to transport). One of the downsides is that the batts need to be cut with a saw and the fibres get everywhere.

Some of the batts needed to be carefully packed around (insulated) pipework, and I needed to form a box section of windproof membrane around the house’s main drainage stack in one corner of the space, since it wasn’t possible to fit insulation or the membrane behind it. I later added closed-cell plastic bubblewrap insulation around the rest of the drainage stack to reduce the chance of it freezing in winter, since the under-floor cavity should now be significantly colder.

As more of the insulation was installed, I could start to staple the windproof membrane to the underside of the joists, and seal the insulation batts in place. The room needed three runs of membrane, with 100mm taped overlaps between them.

With the insulation and membrane in place and taped, the finishing touches in the under-floor cavity were to reinstall the pipework insulation and seal it to the windproof membrane to prevent any (really minor) wind washing of the insulation from draughts through the pipe holes; to label everything; insulate the drainage stack; re-clip the mains wiring; and tie the membrane into the access hatch.

Airtightness work in the kitchen

With the insulation layer complete under the chipboard floor, the next stage in the job was to ensure a continuous airtightness layer between the kitchen walls (which are plasterboard, and hence airtight apart from penetrations for sockets which I wasn’t worried about at the time) and the chipboard floor. Each floor board is itself airtight, but the joints between each of them and between them and the walls are not.

The solution to this was to add a lot of tape: cheaper paper-based Uni tape for joining the floor boards, and Contega Solido SL for joining the boards to the walls (Uni tape is not suitable as the walls are not smooth and flat, and there are some complex corners where the flexibility of a fabric tape is really useful).

Tediously, this involved removing all the skirting board and the radiator. Thankfully, though, none of the kitchen units needed to be moved, so this was actually a fairly quick job.

Finally, with some of the leftover insulation and windproof membrane, I built an insulation plug for the access hatch. This is attached to the underside of the hatch, and has a tight friction fit with the underfloor insulation, so should be windtight. The hatch itself is screwed closed onto a silicone bead, which should be airtight and replaceable if the hatch is ever opened.

The final step was to reinstall the kitchen floor, which was fairly straightforward as it’s interlocking laminate strips. And, importantly, to print out the plans, cross-sections, data sheets, a big warning about the floor being an air tightness barrier, and a sign to point towards the access hatch, and put them in a wallet under the kitchen units for someone to find in future.


This was a fun job to do, and has noticeably improved the comfort of my kitchen.

I can’t give figures for how much of an improvement it’s made, or whether its actual performance matches the U-value calculations I made in planning, as I don’t have reliable measured energy loss figures from the kitchen from before installing the insulation. Perhaps I’d try and measure things more in advance of a project like this next time, although that does require an extra level of planning and preparation which can be hard to achieve for a job done in my spare time.

I’m happy with the choice of materials and installation method. Everything was easy to work with and the job progressed without any unexpected problems.

If I were to do the planning again, I might put more thought into how to achieve a better U-value while being limited by the joist height. Extending the joists to accommodate more depth of insulation was something I explored in some detail, but it hit too many problems: the air bricks would need to be ducted (as otherwise they’d be covered up), the joist loading limits might be hit, and the method for extending the joists would have to be careful not to introduce thermal bridges. The whole assembly might have bridged the damp proof course in the walls.

It might, instead, have worked to consider a multi-layer insulation approach, where a thin layer of high performance insulation was used next to the chipboard, with the rest of the joist depth taken up with the thermojute. I can’t easily change to that now, though, so any future improvements to this floor will either have to add insulation above the chipboard (and likely another airtightness layer above that), or extend below the joists and be careful about it.

How your organisation’s equipment policy can impact the environment

At the Endless OS Foundation, we’ve recently been updating some of our internal policies. One of these is our equipment policy, covering things like what laptops and peripherals are provided to employees. While updating it, we took the opportunity to think about the environmental impact it would have, and how we could reduce that impact compared to standard or template equipment policies.

How this matters

For many software organisations, the environmental impact of hardware purchasing for employees is probably at most the third-biggest contributor to the organisation’s overall impact, behind carbon emissions from energy usage (in building and providing software to a large number of users), and emissions from transport (both in sending employees to conferences, and in people’s daily commute to and from work). These both likely contribute tens of tonnes of emissions per year for a small/medium sized organisation (as a very rough approximation, since all organisations are different). The lifecycle emissions from a modern laptop are in the region of 300kgCO2e, and one target for per-person emissions is around 2.2tCO2e/year by 2030.

If changes to this policy reduce new equipment purchase by 20%, that’s a 20kgCO2e/year reduction per employee.

So, while changes to your organisation’s equipment policy are not going to have a big impact, they will have some impact, and are easy and unilateral changes to make right now. 20kgCO2e is roughly the emissions from a 150km journey in a petrol car.

What did we put in the policy?

We started with a fairly generic policy. From that, we:

  • Removed time-based equipment replacement schedules (for example, replacing laptops every 3 years) and went with a more qualitative approach of replacing equipment when it’s no longer functional enough for someone to do their job properly on.
  • Provided recommended laptop models for different roles (currently several different versions of the Dell XPS 13), which we have checked conform to the rest of the policy and have an acceptable environmental impact — Dell are particularly good here because, unlike a lot of laptop manufacturers, they publish a lifecycle analysis for their laptops
  • But also gave people the option to justify a different laptop model, as long as it meets certain requirements:

All laptops must meet the following standards in order to have low lifetime impacts:

All other equipment must meet relevant environmental standards, which should be discussed on a case by case basis

If choosing a device not explicitly listed above, manufacturers who provide Environmental Product Declarations for their products should be preferred

  • These requirements aim to minimise the laptop’s carbon emissions during use (i.e. its power consumption), and increase the chance that it will be repairable or upgradeable when needed. In particular, having a replaceable battery is important, as the battery is the most likely part of the laptop to wear out.
  • The policy prioritises laptop upgrades and repairs over replacement, even when the laptop would typically be coming up for replacement after 3 years. The policy steers people towards upgrading it (a new hard drive, additional memory, new battery, etc.) rather than replacing it.
  • When a laptop is functional but no longer useful, the policy requires that it’s wiped, refurbished (if needed) and passed on to a local digital inclusion charity, school, club or similar.
  • If a laptop is broken beyond repair, the policy requires that it’s disposed of according to WEEE guidelines (which is the norm in Europe, but potentially not in other countries).

A lot of this just codifies what we were doing as an organisation already — but it’s good to have the policy match the practice.

Your turn

I’d be interested to know whether others have similar equipment policies, or have better or different ideas — or if you make changes to your equipment policy as a result of reading this.