Further Reading: Sustainability

On the citation tiers, see how-to-use-this-book.md.

Three notes, and the first is the most important in this file.

Every emissions figure in this chapter is an order-of-magnitude planning factor drawn from widely published sources, and every one of them is contested at the margins. They vary by methodology, by year, by geography, by whether radiative forcing is included for aviation, and by who is doing the accounting. They are good enough to rank decisions and they are not good enough to report as an audit. A planner who presents a total to three decimal places has overstated what they know. The ranking — travel, then food, then everything else — is robust across almost every source. The numbers are not.

Second: this chapter recommends things that could make an event less profitable for the person recommending them, and §35.9 says so. That admission is in the chapter rather than in a footnote because a reader is entitled to weigh it.

Third: the legal material — food donation protections, sustainability reporting obligations, waste regulations — varies enormously and is changing fast. Nothing here is legal advice and the specific regimes named are examples of a category, not a list to work from.

Tier 1 — Verifiable published sources

Emissions factors and how to use them

Your government's published emissions factors. In the UK, DEFRA/BEIS publishes a comprehensive annual set, free, covering travel by mode, energy, water, and waste; the US EPA, the EU, and many other jurisdictions publish equivalents. This is the correct source and it is better than any calculator.
The GHG Protocol, and specifically the Corporate Value Chain (Scope 3) Standard. This is where the boundary question in §35.2 is actually worked out properly, and it is what a corporate client's sustainability team is applying.
Any current work on aviation's non-CO₂ effects — contrails, radiative forcing, and the multipliers applied to them. This is genuinely unsettled, the multipliers used vary from 1.0 to about 3.0, and it means aviation figures are the least certain and the most consequential numbers in this chapter.
Poore and Nemecek (2018), Science, "Reducing food's environmental impacts through producers and consumers." The single most useful published source on food's footprint — the dataset behind almost every per-food figure you will see, including the finding that transport is a small share of most foods' impact. Read it or a good summary of it before arguing about "local."

Food, waste, and donation

Your jurisdiction's food-donation liability provisions. In the US, the Bill Emerson Good Samaritan Food Donation Act and its 2023 amendment; many other countries have analogous provisions. Read the actual text and its conditions, not a summary.
Your food-safety regulator's guidance on donating surplus. This is the part that is not waived by any liability protection and it is the part caterers are right to care about.
Any national food-waste-reduction body's guidance for the hospitality sector. Several publish practical, free, sector-specific material that is better than anything in this chapter.

Waste, materials, and the compostables question

The standards behind compostability claims — EN 13432, ASTM D6400, and their equivalents. All of them specify industrial conditions. Reading one is the fastest cure for the assumption in §35.6.
Your local authority's or waste contractor's actual accepted-materials list. This is the document that determines whether your compostables are compost, and it is not the venue's sustainability page.
Any current work on microplastics and glitter, for the confetti question — and note that "biodegradable glitter" claims vary enormously in what they mean.

Corporate reporting

The CSRD and the ESRS, in the EU; your own jurisdiction's equivalent. You do not need to be able to comply. You need to know the questions are coming and what shape of data answers them.
Any guidance on business travel reporting under Scope 3. This is where an event's largest line becomes somebody's disclosure obligation, and §35.8a's activity-data pack is the thing that makes it answerable.

Offsetting, honestly

The current criticism of the voluntary carbon market. There has been substantial investigative reporting and academic work finding that a number of high-profile schemes delivered far less than claimed. Read some of it before buying anything.
The Oxford Principles for Net Zero Aligned Carbon Offsetting, or a comparable framework, for what a defensible purchase would actually require.

Event-specific standards

ISO 20121, the event sustainability management system standard. It is a management-system standard, not a performance standard — it certifies that you have a process, not that your footprint is low. Knowing that distinction is most of what is worth knowing about it.
Any sector event-sustainability guidance you can find. Read it against §35.1's ranking and note how many of them address the two lines that dominate. Exercise E.4 makes you do this.

Tier 2 — Attributed professional practice

The seven-line footprint ranking, and the 50–90% travel figure. Consistent with published event studies and stated here as a shape. Proportions vary enormously by event type.
The eight-step estimation method. The author's, and it is a deliberately crude approximation of a proper inventory. Its claim is only that steps 2 and 4 are most of the answer, which is well supported.
The eight travel levers in order. Practice.
The four food levers. Well supported by Poore and Nemecek for the first and fourth; the second and third are practice.
"Most event sustainability is theatre." The chapter's central and most provocative claim, and D.1 asks whether it is fair. The author's position: it is a claim about arithmetic, not about sincerity, and the chapter says so twice.
The five questions for evaluating a claim.
§35.7's costs-nothing / costs-money split. Practice, and it is the argument that survives a budget conversation.
The three rules for telling guests, and the model paragraph. The author's.
§35.9's conflict-of-interest admission. Not standard in this industry's literature, and it should be.
The activity-data pack as a chargeable service. The author's, and it is the most commercially useful idea in the chapter.

Tier 3 — Illustrative and constructed

All case-study material. The Verdance Institute conference; the Reyes–Whitfield footprint, diversion plan, and every number in it. Constructed.

Three specific notes.

Both case studies' arithmetic has been checked line by line and reconciles. The Verdance figures (151.5 t, 88% aviation, 4.2% touched by the programme, 39% reduction in year two) and the Reyes–Whitfield figures (8,499 kg, 94% travel, 522 kg for everything else, 89.6% diversion, 0.13% of carbon) are internally consistent estimates on constructed inputs and are not measurements of anything.

Case Study 35.1's compostables-to-landfill failure is the chapter's most useful constructed detail, because it is common, because the diversion figure was computed correctly and answered the wrong question, and because the fix — hiring reusable crockery — does not depend on any facility existing.

Case Study 35.2's central finding is deliberately anticlimactic. The most effective environmental decision on the wedding was a guest-list cap made for money in month one, and the chapter's whole diversion plan is 0.13% of the carbon. A case study that made the sustainability work look decisive would be a more satisfying chapter and a less honest one — and DQ4 argues that saying "0.13%" out loud is precisely what protects the plan from Case Study 35.1's fate.

Where to go next

Download your government's emissions factors and compute one event, using the eight steps (B.1). One hour. The ranking will surprise you and it will change where you spend effort.

Read Poore and Nemecek, or a good summary. It will end every argument you have ever had about local food.

Ask one venue what actually happens to each waste stream (C.2), and ask the waste contractor whether a commercial composting facility is used (C.4). These two calls take fifteen minutes and one of them will disappoint you.

Read one compostability standard (EN 13432 or ASTM D6400). Ten minutes, and you will never again buy a compostable cup without asking a second question.

And do the last step of the mini-project: show the footprint ranking to whoever chose the venue. Their reaction — surprise, defensiveness, or relief — tells you whether the conversation was ever available, which is the thing §35.3 is really about.

Part VIII preview

Part VII ends here. Part VIII is the business: starting a planning company, pricing, marketing, and the systems that make a second wedding better than a first.

Chapter 36 opens with a number too — and it is the one most people in this industry find out too late.

Not what you charge. What an hour of your time costs you before you have earned anything at all.