• Notes And Data for The Carbon Diet

    Find out more about how I calculate each week's results.


    - Spreadsheet calculations are here. Data sources are set out on that spreadsheet.

    - My data is much more rubbery than usual. The Australian average figure is a top-down estimate based on waste generation rather than the purchase of goods, so it omits all the stuff we buy but don't get around to throwing out, like unworn clothes in a wardrobe. This is known in the waste industry as the 'above-ground landfill'. No one knows how big it is but we're all worried about the day it shows up at the tip. I've made a bunch of assumptions about how much of this total waste stream comes from the goods purchased by an individual (like clothing, electronics, furniture and toys) as opposed to other stuff (like waste from building and demolishing houses or providing medical services ). All around, this guesstimate is pretty rough.

    - The audit of my own stuff is based on our last six months' of bank records and a really good look around our house. I'm sure I've missed a few things but it should be pretty comprehensive.

    - I've applied UK Government emission factors on 'Material Use' to both sets of data because our government doesn't maintain this kind of data. True Australian emission factors are probably higher as we tend to have bigger transport distances, more air freight and more intense electricity in our grid, but I can't say for sure. Quote my data at your peril.


    - The best way to cut carbon from your food footprint is to eat a plant-based diet. Vegan makes the biggest savings, but vegetarian and smart supermarket swaps also make big savings. 5:2 fasting can cut carbon but only if you stick to plant-based foods on the fasting days. Cutting food waste cuts carbon. Other ideas, like eating local, seasonal and organic and reducing plastic packaging, don't cut much carbon and may backfire.

    - Data on the carbon impact of the 'average' Australian diet, embedded emissions in food waste, 5:2 fasting, vegan diet and vegetarian diet are here.

    - Data on carbon implications of plastic packaging and what happens if you try to avoid it are here.

    - Data on a smart supermarket swap (reducing meat, dairy and fish and changing the type of meat chosen) are here.

    - Data on an infographic about animal-based versus plant-based foods is here.


    - Spreadsheet calculations are here. Data sources are set out on that spreadsheet.

    - The last tab titled 'Efficiency' is blank. That's because I haven't checked the data. I've based my 50% energy savings on experiments and research conducted over the last thirty weeks but I want to check it. I'm going to record my power usage each month over the next 12 months, post-efficiency measures. I'll report back at the end.

    - I asked half a dozen solar industry gurus about embedded emissions in rooftop solar. No one could answer. I used an overseas academic pilot study, but if you know of a good local LCA, send it through!


    - Spreadsheet calculations are here. Data sources are set out on that spreadsheet.

    - I couldn't separately meter or measure either our solar hot water system (which uses very little electricity) or our electric-booster. I've used some industry figures to estimate this. They look fairly consistent with Australian averages but I suspect there's a massive difference between one system and the next. Usage patterns also change from one family to the next. This is another area where it pays to watch your own usage and bills. Also do your research and get multiple quotes if changing systems and monitor the performance of a new system to make sure it performs as promised.


    (opinion piece published by ABC News 2 June 2019)

    - I've said we pledged to drop from 21 tonnes to 20 tonnes of CO2e per person per year. That's based on government data and government targets, but they're not usually expressed as a per-person figure. Here's how I calculated it. The report 'Australia's emissions projections 2018' (Department of the Environment and Energy December 2018) gives Australia's 2018 emissions as 534,000,000 tonnes CO2e (including LULUF), which is around 21.3 tonnes CO2e per person per year. The report says our 2020 target is to reduce emissions by 5% below 2000 levels by 2020. The National Greenhouse Gas inventory gives Australia's 2000 emissions as 551,786,930 tonnes CO2e, so a 5% reduction on that would be 524,197,584 tonnes CO2e per year or around 20.2 tonnes CO2e per person in 2020. I've used ABS population projections of 25,029,253 for 2018 and 25,936,500 people for 2020.

    - The article draws on research and calculations made for Weeks 5, Weeks 11 - 18 and Weeks 23 - 24 of this project. Check the posts and notes for details for those weeks.

    - Data and sources for the Drinks Infographic is here.


    - Spreadsheet calculations are here. Data sources are set out on that spreadsheet.

    - This week's experiment got complex. I found my % efficiency savings were much higher than those I'd researched. Perhaps our devices are increasingly using more power so the savings are consequently larger? This is why I picked a 25% 'average' saving on electricity overall rather than one of the lower saving % I'd read about.

    - I tried to get numbers on embedded emissions in a fridge versus efficiency savings on a newer model based on this LCA, this LCA and this LCA. It was tricky. I also got advice from Southcoast Health and Sustainability Alliance (SHASA) which indicated that 10% of a fridge's footprint is in embedded emissions and 90% in ongoing power usage for a ten-year life. SHASA certainly thought old fridges should be replaced before they break. It's hard to give a definite number without an LCA based on a model and current power usage in action (not based on specs). In the end, I decided to replace my cracked seals instead, which was cheap and a no-brainer. Definitely replace old seals. Probably replace old fridges, if you can afford the outlay.

    - Getting off gas is a great idea for the planet, but my house is on gas and my budget doesn't extend to major renovations. To make sure I'm comparing like with like, my Australian averages in this post are for a house connected to gas. If you're off gas, your electricity use may be higher than these numbers, but your overall emissions should be lower. Don't go back to gas.


    - Spreadsheet calculations for domestic flights here. Data sources are set out on that spreadsheet.

    - My factors give a much higher figure than either the Australian Government or QANTAS figures. I've had a dozen emails back and forth to try and work out why. On international flights, the government only counts half the trip because they only count fuel bought in Australia. This makes my figures and government figures broadly compatible (but I count the whole trip, not half of it). On domestic flights, government counts fuel for the full trip as it's all bought and used in Australia, so that reason doesn't apply. Both QANTAS and government come up around half my calculation on domestic flights. They're using much lower emission factors. I'm using the same set of UK industry factors for both domestic and international flights. The UK industry factors that I use are fairly standard in the industry and are used by some Australian state governments.


    - Spreadsheet calculations for my household gas usage, ACT and Australian averages here. Data sources are set out on that spreadsheet. I've used 2018 figures for ACT + the latest grid emission factors for NSW/ACT grid. I've used 2012 ABS figures for Australian consumption + latest grid emission factors for Australia.

    - Households using a high-emission electricity grid, like those in Victoria, may not make immediate CO2e savings by building new houses with electricity only and switching old systems and appliances from gas to electric at the end of their life. But the emissions intensity of all grids is dropping. This means electricity is a better bet for the future, even in Victoria.

    - I use less gas and electricity than the average Australian. The average ACT household uses more than the Australian average.

    - This week's experiment only looks at natural gas used directly in the household. It omits natural gas burned to produce grid electricity, LPG fuel for cars and other sources of gas use.


    - Spreadsheet calculations for my household electricity emissions and the ACT average here. Data sources listed on that spreadsheet.

    - Federal Government data on grid electricity mix from Australian Energy Regulator here. Clean Energy Council data on grid electricity mix here. The data sets are slightly different but similar enough to be comparable. Perhaps the Clean Energy Council data is more up-to-date?

    - General information about Australian household energy consumption from the government's Australian Energy Regulator report.


    - Spreadsheet calculations are here. Data sources are listed on that spreadsheet.

    - See notes for Week 22 below re. data sources & uncertainty. I suspect I've overestimated the impact of coffee by using a high emission factor, as I've since found studies listing much lower ones. I'm also surprised at the high level of 'average' consumption of soft drinks and diet drinks, but that's what my sources said. Let me know if you have better source data.


    - Spreadsheet calculations are here. Data sources are listed on that spreadsheet.

    - As noted in the post, I used data on average drinks consumed by an Australian adult from ABS, Statistica and a Choice magazine article. They'll all recent but they apply to different periods and use different categories. They should absolutely not be used the way I'm using them. My figures on sugar-sweetened and diet drinks looked high. As with food, drink 'averages' aren't that helpful, because there's so much variety. I drink no soft drink at all because it's evil and ruins your health, but my wine and coffee habit would shock the 3-cans-a-day energy drink kids. We're all individuals, except Brian.

    - There's even patchier data on drink emission factors than there is for food emissions and no Australian government sources that I could find. If you find better, more relevant data that doesn't cost $4000, pls let me know.


    - Spreadsheet calculations are here. Data sources are listed on that spreadsheet.


    - Spreadsheet containing this week's meter readings & carbon calculations, a basic weather comparison between my baseline week and this week's experiment, my baseline usage and averages usage is here. Sources are labelled on that spreadsheet.


    - Spreadsheet for baseline carbon analysis is here. Data sources and factors are labelled on that spreadsheet.

    - My usage over the past week is higher than my average summer usage taken from our last three years of electricity bills. It's probably because we're in peak summer right now, and it was a heatwave. But these are the only one-week meter readings I have. In any case, 2019 summer is probably hotter than the 2016 summer, and looking at a 3-month average ignores the fact that I'll use the cooler less in December and February than I will right now for this 3-week consecutive period in January.

    - I have electricity usage for my household for the past 10 years, but I'm not referring to data before 2014 because it's not comparable to my current lifestyle. In 2014, I had a baby and have since been working a great deal from home, so our at-home usage has increased. Prior to that, we were a two-person household, we both spent five days per week in offices in town and we travelled a lot, so the data doesn't match.


    - Spreadsheet for my baseline diet compared to the supermarket swap is here.

    - Spreadsheet for average Australian Molloy baseline diet compared to the supermarket swap is here.

    - Spreadsheet showing progress to date is here.


    - Spreadsheet for carbon analysis is here. Data sources and factors are labelled on that spreadsheet. Some data comes from previous week's experiments eg. food baseline and waste factors.

    - I wasn't sure whether to include direct landfill emissions or only embedded indirect emissions. I already counted direct landfill emissions from household food waste in weeks 2 - 4 and I don't want to double-count that, but I haven't covered direct landfill emissions from non-household waste (businesses, food industry, farm etc). But then I've also omitted food rescue, which salvages some of that business waste so that it doesn't directly emit from landfill. In the end I've only included indirect embedded emissions in food waste based on adding another 33% to the weekly shop to allow for food waste.


    - Spreadsheet for carbon analysis is here. This is my baseline diet from Week Eleven with notes on local, seasonal and organic labelling in the two supermarkets I shop at, Coles and Aldi. It gives a 9% discount for organic plant foods and no discount for local or seasonal.

    - Coles has some good online tools under 'Corporate responsibility' showing whether produce is imported and whether it's seasonal, but these didn't show carbon footprints, whether it's air-freighted, whether it comes from a hothouse and if so, what kind. Aldi and Woolworths also have corporate responsibility information on their websites, but they didn't provide the information I needed.

    - The studies I've cited are linked in the blog post. Other studies I used but didn't cite are here, here, here, here, here and here.

    - I'm using academic sources, primarily Life Cycle Analyses. There's always a risk that I won't be comprehensive and that I'll cherry-pick. I try to keep a genuinely open mind and I was surprised at this week's results. I'm a local / seasonal / organic gal by nature, so I certainly didn't exclude studies that backed those up. Please contact me if you think I've ignored important sources.


    - Spreadsheet for carbon analysis is here. All data sources are labelled in that spreadsheet.

    - Only 3% of my food footprint came from packaging, but my household runs low on waste (see Weeks 2 - 4). However, we also run low on overall food emissions. I suspect there's a relationship between food emissions and packaging ie. those who generate high emissions from their food by eating lots of meat and wasting a lot of food probably generate high emissions from their packaging too, thus the packaging to food emissions ratio may remain consistent. In any case, packaging accounting for 3% of the carbon footprint of food is consistent with research.

    - I only looked at upstream production emissions in my packaging, not downstream landfill emissions. I looked at landfill in Weeks 2 - 4. In any case, most of my packaging was recycled.

    - I used a 2016 United States study for my packaging emissions factors. I couldn't find an Australian study. The energy sources make a huge difference, ie whether the energy came from high-emissions coal, low-emissions renewables or something else. I don't know if the US energy mix and production data were the best ones to use, but it's what I found. Most packaging in Australia is made overseas in many different countries. The precise data may not exist.


    - Spreadsheet for carbon analysis of my vegetarian diet versus my baseline diet is here.

    - Spreadsheet for carbon analysis of Molloy diet is here.

    - I wasn't planning to test vegetarianism in addition to veganism, but research showed that vegetarian is much more mainstream than most other variations I'm testing. It seemed important. This has set my project back so I'll need to cram a few experiments into my final week to stay on schedule.


    - Spreadsheet for carbon analysis is here.

    - Most emission factors came from 'Systemic review of greenhouse gas emissions for different fresh food categories' by Clune, Crossin & Verghese, published in Journal of Cleaner Production 140 (2017) 766-783. Other sources as labelled in that spreadsheet.

    - For most processed foods, I've averaged the emissions for key ingredients and then multiplied by four to account for the fact that there's more fresh produce going into a processed item, more waste, greater energy costs, more packaging etc. My formula might work for heavily concentrated or dried items, because the fresh item is heavier and therefore less carbon intense per kilogram eg. tomato paste versus tomatoes, olive oil versus olives. It probably overestimates the emissions factor for other processed foods. I've labelled throughout and I'll stick with the same method for consistency, but I'll review this at the end of the project and revise if needed.


    Spreadsheet for carbon analysis is here. This shows the carbon footprint for the Molloy diet per person per week, my typical diet per person per week and my diet on the two 'fasting' days when I ate lentil pumpkin soup and smoked salmon salad. I've also included a carbon analysis for several other 5:2 recipes set out in Dr Michael Mosley & Mimi Spencer's book of the same name. I didn't try these - they looked delicious, but carbon-intense.


    My food diary, food costs and CO2e calculations are here.


    Notes and references

    - Most emission factors came from 'Systemic review of greenhouse gas emissions for different fresh food categories' by Clune, Crossin & Verghese, published in Journal of Cleaner Production 140 (2017) 766-783. This study is a literature review of various LCAs intended to produce a 'league table' for the carbon footprint of various foods. Largely Euro-centric with some Australian data. It includes emissions up to the retail distribution centre such as farm inputs (fertilisers, feedstocks); fuel & energy for cultivation, harvest & processing; transport & refrigeration to the retail centre, direct emissions from plants and animals. DOES NOT include transport from home to shops, food storage & cooking at home, food disposal, packaging disposal or sewage.

    - CO2e factors for snack foods came from this study https://academic.oup.com/ajcn/article/101/1/184/4564263.

    - See also 'Food systems and environmental sustainability: A review of the Australian evidence. NCEPH Working Paper. Canberra: Australian National University, paper by Bradbear C and Friel S (2011).

    - My CO2e estimates only apply to the pre-supermarket impact of food (ie. the pink section in Figure 1 main article). I'll cover most of the blue section elsewhere in this project (eg. household waste, transport and electricity). In any case, the pink section likely covers at least 70% of my total food footprint. - Rest assured, while my kilojoule intake looks low on some days, I made up for it with booze. I didn't measure this. I'll come back to that at a later stage when I look at coffee, alcohol and other drinks.


    No calculations made for solar versus GreenPower due to complexity. Calculations about progress on my personal carbon cuts and cuts against the Australian average are below.





    - Spreadsheet on gas and electricity differences & CO2e from Week Nine experiment:

    https://uploads.strikinglycdn.com/files/422b3360-8352-48f4-b6bb-976539d4a980/Week 9 - gas and electricity difference with window insulation & draught proofing.xlsx?id=129595

    - I estimated the embedded emissions in my faux double glazing and draught tape at 25 kilograms in total, amortised over 5 years (ie. 5 kilograms per year). This was based on YourHome (Australian Environment Department) Process Energy Requirement for plastic of 90MJ/kilogram (around 25 kilowatts). If taken as electricity from the ACT/NSW grid, 25 kilowatts would generate around 12.5 kilograms CO2e. I've doubled this as a Process Energy Requirement only accounts for 50 to 80% of the total Gross Energy Requirement for a product.




    - Spreadsheet on gas and electricity differences & CO2e from Week Eight experiment

    https://uploads.strikinglycdn.com/files/6c658fba-6279-4c1d-98cf-b229889c3957/Gas and electricity difference with heater off.xlsx?id=127608




    Data sources

    - 'Australian international travelers: the places we go" from Department of Foreign Affairs and Trade paper at dfat.gov.au/about-us/publications/Documents/australian-international-travellers-the-places-we-go.pdf

    - 'Greenhouse gas reporting - Conversion factors 2016' from UK Government at www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2016, as referenced by EPA Victoria. Includes radiative forcing. These figures are used as flights are not included in the National Greenhouse Accounts Factors (Department of Environment and Energy).

    - Return journey distances from www.airmilescalculator.com.


    Data notes

    I used figures for Australian 2016 flights. The Department of Foreign Affairs and Trade (DFAT) estimates flights are increasing by 5% each year, so figures would be higher for 2018. The DFAT paper also acknowledges that their figure underestimates Australian international travel when compared to overseas data. The DFAT figures also only look at the first destination, not multi-destination trips. All around, CO2e generated by Australian residents taking international flights is probably much higher than indicated.



    https://uploads.strikinglycdn.com/files/969ba380-7b4e-4512-a450-bf584519ede8/Flight calculations.xlsx?id=125113




    Data sources

    - Pet ownership statistics from Animal Medicines Australia 'Pet Ownership in Australia 2016'


    - Experimental meat-free diet for sprint-racing sled dogs (2009 study). https://www.ncbi.nlm.nih.gov/pubmed/19480731

    - Cats kill 377 million birds each year.


    - GWP emission figures for different food types. 'Systematic review of greenhouse gas emissions for different fresh food categories', Clune, Crossin and Verghese, Journal of Cleaner Production 2017, http://www.elsevier.com/locate/jclepro


    Data notes

    I used GWP emission figures for fresh human-grade bone-free foods. These may be too high for meat in particular, as pet food is typically rendered offal rather than prime bone-free cuts so it is using up 'waste' food. However, I didn't add anything for air freight, canning, refrigeration, home cooking, home transport etc, so it might balance out. And in other countries, people eat a lot of this 'waste' food, so who's to judge?



    https://uploads.strikinglycdn.com/files/0bed47f3-9d4a-4202-86b6-9799132360be/Dog Food Four Scenarios.xlsx?id=117732




    Data sources

    - Greenhouse gas from backyard composting. 'Emission of greenhouse gases from home aerobic composting, anaerobic digestion and vermicomposting of household wastes in Brisbane (Australia) by Chan, Sinha and Wang of Griffith University and Department of Environment and Resource Management (QLD), study conducted January to April 2009 in Brisbane. file:///C:/Users/Joanne%20clay/Downloads/Data_for_2_-_Emission_Paper.pdf

    - Methane capture in ACT landfill. ACT State of the Environment Report 2007 by the Commissioner for Sustainability and the Environment at https://www.envcomm.act.gov.au/soe_about-the-report/soe_archive/2007actreport


    Data limitations

    - Household kerbside waste only. My waste analysis only looks at household waste in kerbside bins. It omits anything you discard at work, and anything discarded on your behalf by a business (like commercial waste and construction waste).


    - Only CO2e from landfill. I looked at estimates of landfill greenhouse gas emissions. I did not include emissions to transport the waste to recycling centres and landfills and to process it at those facilities. On the flip side, I also left out greenhouse gas emissions from home compost and backyard chicken systems. Did all this balance out? No idea.


    - Dog poo. I classified dog poo in plastic bags as 'other organics' and used an emissions factor of 0.6 They should perhaps instead have an emissions factor of 1.8 like nappies. My quantities were so low, this had little effect on results, but at higher volumes it would be significant.


    Spreadsheet calculations

    Waste Audit & Calculations




    Information about Material Recover Facilities (Resource Recovery Facilities) from Australia's waste and resource recovery infrastructure from the National Waste Report 2013.


    Spreadsheet calculations

    ACT Household Waste Bin Audit & My Bin Audit



    Data sources

    - Chinese waste ban at http://www.abc.net.au/news/science/2018-03-03/recycling-industry-in-crisis-can-it-be-fixed/9502512

    - Australia's Annual Waste data 2014-15. Australian National Waste Report 2016 at https://www.environment.gov.au/system/files/resources/d075c9bc-45b3-4ac0-a8f2-6494c7d1fa0d/files/national-waste-report-2016.pdf

    - ACT 2014 waste data. Appendix C Detailed Waste Composition, Domestic Kerbside Waste Audit 2014 (ACT) at https://www.tccs.act.gov.au/__data/assets/pdf_file/0018/1131840/2014-ACTNoWaste-domestic-waste-audit-report-FINAL-v2.pdf

    - Co2e conversion factors. National Greenhouse Accounting Factors 2017, Appendix 4, Table 42: Waste mix methane conversion factors. http://www.environment.gov.au/system/files/resources/5a169bfb-f417-4b00-9b70-6ba328ea8671/files/national-greenhouse-accounts-factors-july-2017.pdf

    - My household waste data. Personal bin audit for one week conducted 5 May 2018, see below.


    Data limitations

    - Methane from landfill. Some landfills capture some methane, and some are uncapped and don't capture any. Waste also releases methane over decades, not in the year it is interred. Waste that is composted at home may also generate CO2e, although this should be much lower than for anaerobic decomposition in landfill. For simplicity, I've ignored all this and simply used the National Greenhouse Accounting Factors 2017 for methane from waste in landfill.


    - Australian versus ACT data. I've used different data sources for Australian and ACT data. These may not be comparable. Of note, my figures say annual Australian municipal waste generation is around 565kg per capita and annual ACT municipal waste generation is around 300kg per capita. I don't know if this is a genuine difference or a result of different data collection methods. For my project, I'm relying on the ACT figures.

    - My bin audit. I only audited one week's waste. This may not be representative. I had planned on conducting several audits but decided not to bother, given the low volume of waste and CO2e generated. I'll conduct the experiment by taking the recommended actions, but showing what impact they'd have on ACT averages.


    Spreadsheet calculations

    Australian & ACT Waste Data


    ACT Household Waste Bin Audit & My Bin Audit


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