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Invoice layout with impact


For CKW, the electricity bill is the most frequent and most important touchpoint with customers. Find out how we used a behavioral economics experiment to identify the most effective nudges and ensure a clear, customer-friendly layout.

Challenge and goal

"Electricity bills must be 'simple and understandable'". In Germany, this is already stipulated by law (EnWG § 40 Abs. 1). For CKW, however, the design of bills is also key from a strategic point of view: electricity bills are the most frequent and most important touchpoint with customers. In order to optimize this touchpoint, CKW comissioned the Ergonomen to develop a standard layout that can be used as a basis for all customer segments. The new invoice layout should cover the possibilities of modern digital communication across all channels. It should also comply with legal and regulatory requirements and take into account the general specifications of the brand manual.

Website vor Optimierungen

Fig. 1: CKW invoices before the redesign.

Procedure and method

As a first step, we analyzed the requirements from the customer's perspective: What information is particularly important? Which needs are not yet being adequately met? To find answers to these and other questions, we collected input from internal stakeholders through interviews and a survey, as well as launching a customer survey.


Fig. 2: Interviews and surveys were used to gather requirements.

Based on this user research, we developed an initial concept for the new invoice layout. In addition to comprehensibility and clarity, we also focused on the integration of nudges to achieve strategic goals (e.g. switching to e-bills).

To test the effect of different nudges, we conducted a behavioral economics experiment with a censored logo. For this purpose, variants of the nudges were developed that differed in terms of UX writing. During the survey, the participants saw one of four variants. On the next page, they indicated what they would do next (e.g. switch to eBill). We statistically analyzed the results to identify the most effective nudges.

Fig. 3a: What is the most effective nudge towards eBill?

In addition, we tested various display formats in an A/B-test to find out whether 1-page account calculations are preferred over 2-page ones and which graphic presentation has the clearest effect (UX design).

Fig. 3b: Which presentation is the clearest?

Based on the findings, we further developed the invoice layout and tested its acceptance in a usability test. A total of 9 target group representatives were shown drafts of various invoices, and their impressions were consolidated and evaluated.


The results of the acceptance test have shown that the new invoice layout is very well received by customers: compared to the old layout, the invoices are judged to be clearer, easier to understand and more appealing. And the nudges, which were optimized using behavioral economics approaches, are having the desired effect.


Fig. 4: CKW invoices after the redesign by the Ergonomen. 

Customer benefit

The Ergonomen provided CKW with a style guide with design specifications for the implementation of the new design both in the invoice layout and in other stationery. This marked the end of another successful project with CKW after just under 9 months. We are proud to have used quantitative and qualitative research methods in an iterative process to achieve the optimum for CKW's new invoice layout.

The collaboration with the Ergonomen has always been inspiring. With their wide-ranging expertise in usability, behavioral economics and generally a fresh outside perspective, they have already supported us in several projects. When setting up the projects, their advice was always competent and they responded to our needs. The joint projects led to the optimization of important customer touchpoints.
- Eva Schär, Customer Experience Manager

Interested? Contact us!