Foreword: For those that aren’t familiar with the Tableau Iron Viz competition, Iron Viz is the ultimate battle of Tableau skills. Three challengers are selected based on contests held through Tableau Public. These contests are centered on a specific topic or theme. There are two competitions each year; one in Europe (at the European Tableau Conference) and a bigger competition at the main Tableau conference in the US. In each competition the challengers face off head-to-head in a 20-minute viz battle in front of a live audience of thousands held at the respective Tableau Conference. The winner, as decided by the a panel of judges and a crowd vote, is crowed Iron Viz Champion!

Iron Viz Europe is particularly special to me. Having made it to the final of the competition in 2018 I have fond memories of the experience, right from entering the feeders to building a viz on stage at Tableau Conference Europe in London. I was particularly excited to enter again this year and experience the buzz around the Iron Viz feeders once more.

The Theme | Energy & Sustainability

Prior to the announcement of the European Iron Viz feeder theme (on my birthday in fact) I had announced the Iron Quest theme would be environmental issues for the month of March. As such, I had already been thinking about viz ideas and doing some light research into different topics. As you can imagine, I was pretty happy when the Iron Viz Europe feeder theme of ‘Energy and Sustainability’ was announced as it tied in nicely with a few ideas I already had for Iron Quest.

Sources of Inspiration

I was scrolling through Twitter one day in early March and the latest Glastonbury Festival poster caught my eye:

Glastonbury 2019.jpg

The dark background and bright colours are particularly striking and I thought it would be fun to incorporate them into a viz somehow. This got me thinking about the design of music festival posters in general and I began searching through them on Pinterest. In doing so, I learned about the ‘Drastic on Plastic’ initiative which aims to eliminate single-use plastics from music festivals in the UK. In fact, Glastonbury have banned single-use plastic water bottles this year in favour of reusable ones. However, while this was an interesting topic the data specifically around plastic bottle waste created by UK music festivals was very limited.

While researching plastic bottle infographics for inspiration on Pinterest (my go-to site for design inspiration) I had stumbled across some articles on plastic bags. After giving up on the festival plastic bottles idea I continued my search but shifted my focus to plastic bags. I began tagging anything interesting I found to a Sustainability board which you can view here. If I’m struggling for design inspiration I usually browse Pinterest and end up down a rabbit hole. To avoid that happening this time I was quite strict with my searches and only pinned things which I found particularity interesting or inspiring.

I decided to go with the plastic bag topic because I thought it would be something everyone has an awareness of and can relate to. While there have been some great vizzes published on fossil fuels or pollution, these topics can sometimes be more difficult to digest. However, we have all used plastic bags at some point, regardless of where you are in the world so we are very familiar with what they are and how they are used. Single-use bags are cheap, convenient and (until recently in the UK) were very commonplace. However, countries around the world are beginning to realise how damaging they are to the environment so they are implementing policies to curb their usage. I suspect that many people who read my viz will have experienced these policies first hand so will have an appreciation of these policies and how they impact the consumer.

More Research & Data Collection

I did a lot of background reading for this viz. In fact, most of my spare time over the course of this project was consumed reading articles about plastic bags and the impact of charges on plastic bags around the world. I wrote pages of notes, I bookmarked lots of websites (in fear I would read something and forget the source to refer back to) and began collecting data. In some cases I was able to download large data sources like the one published by DEFRA which includes details submitted by retailers since the 5p bag charge was introduced in England in 2015. I was also able to source some data from Wikipedia tables using the IMPORTHTML function in Google Sheets. However, in many cases the data was contained within lengthy PDF publications or in static graphics. Where possible I copied small tables into Excel and reshaped them as necessary but in other cases I simply typed the data out manually. I ended up with approximately 10 separate data sources of various sizes.

The Design

Iron Viz is judged on three criteria;

  • Design
  • Storytelling
  • Analysis

Through my research I felt I had found a great story which I could back-up with analysis to support my findings. However, I knew I would need a great design to tell the story effectively. While I love to be creative, I can really struggle to apply good design principles at times. I am on a constant mission to improve my design skills and often look at other peoples work and wish my design skills were that developed. As always, practice makes perfect so I use opportunities such as #MakeoverMonday to practice and experiment with new design techniques.

With this viz I was keen to pay particular attention to;

  • Use of colour
  • Placement and spacing
  • Fonts and font sizes
  • Text arrangement
  • Use of supplementary graphics

In true Andy KirkThe Little of Visualisation Design” style, I browsed through my favourite vizzes and noted down the design elements that took their vizzes from good to great. I took photos of elements that I thought had been executed well; things like the style of annotations placement of items and the use of sub-headers so I could refer back to these later.

I stumbled on a blog post by Ken Flerlage which describes how he built his “Killing Fields” viz for an Iron Viz feeder a few years ago. This viz is full of fantastic design elements so I took lots of inspiration from it. I also had a great chat with Kevin Flerlage (notice the theme here) on our #IronQuest feedback call which helped me to develop a few more ideas.


I spent a lot of time experimenting with colour palettes on ‘The Data Colour Picker” before deciding on my colour palette. I initially wanted to use a contrasting highlight colour to draw out key elements but I decided against this in the end and instead went with a diverging turquoise palette.

Placement and Spacing

I used the dashboard grid in Tableau for the first time with this viz. It’s amazing! This viz is 100% floating so it saved me lot of time in manually aligning items perfectly. It also helped me to keep the spacing between elements consistent.


I downloaded a custom font for my title and sub-headers. Since this font is not compatible with Tableau I wrote the individual elements in PowerPoint and imported them into Tableau as images. This ensures the font displays correctly on Tableau Public, etc.

Breaking Bag Habits.PNG

Supplementary Graphics and Icons

I spent a lot of time designing elements of my viz in PowerPoint this time. I used it as a testing ground to experiment with colours and to get creative with the different graphics. For instance, I downloaded an image of a plain white plastic bag and used it multiple times in different forms in my viz.

Here I wanted to show a disappearing effect to represent decomposition so I used the same image with different levels of transparency to achieve this effect:


I also gathered lots of facts I was keen to include in my viz. In order to display these in an appealing way I built some bubble call-outs in PowerPoint, inspired by those in Ken’s viz:

Stats - EU bag use 2010

I also used various icons downloaded from The NounProject throughout the viz, such as this clock:

12 Mins Life

The Curvy Slope Chart

A few weeks before I built my viz, Kevin Flerlage had published a tutorial on how to build curvy slope charts and bump charts. I was keen to try this technique myself and my requirement to show the decline in plastic bag usage (in particular by Tesco) proved to be the perfect opportunity.

I really like how this chart turned out:

Slope Chart

The Pile of Bags

I wanted to visually represent the sheer number of bags consumed per person every year in the UK prior to the introduction of the 5p charges. I felt this would be more impactful shown in a unit-type chart rather than a bar chart or similar. Once of my favourite vizzes is “Consumed” by Anya A’Hearn. In this viz, Anya shows everything she uses in a typical day in a big pile. This viz contains everything from essential furniture, to clothes and make-up. To apply the same technique in my viz I reverse engineered what Anya did and used this to build my pile of plastic bags. Initially I used images of plastic bags from the major supermarkets such as Tesco and Sainsburys but this looked too messy so I changed all of the bags to a similar shade of blue:

Plastic Bag Pile.PNG

The Transparent Shape Map

I wanted to contain my map in a magnifying glass object but maintain the map interactivity. I achieved this by using the new transparent sheets feature in Tableau.

You can read my tutorial on how I achieved this here.

Map_Completed Example

Space Saving Tricks

Initially my viz contained a lot of text. This was something that others called out when I asked for feedback. In an effort to save space I ended up placing some additional information in information icon tooltips, like this one:

Ireland decline

I also did the same for my data sources (there are quite a few).

The Finished Viz

(Click image to view on Tableau Public)

Breaking Bag Habits v3

Thanks for reading.