## 2 Design of Natural Experiment
The digitization process of the electricity sector in recent decades has created new services, products and markets, in addition to reshaping existing technical systems and infrastructure. New mechanisms are put in place with data generated by numerous smart devices connected in a so-called network Internet of Things, and opportunities arise in the context of energy and electricity markets [3]. The digitalization of energy services can improve utility providers' understanding of increasingly uncertain energy production and consumption, while encouraging a better way of communication with electricity consumers and providing electricity consumers with new information about their use of electricity. Smart grids paired with smart meters provide both supply and demand valuable real-time information on energy flows and consumption, giving also consumers more control over their energy usage, and enabling the development and expansion of demand-side management programs, contributing to needed flexibility in volatile energy systems. In such fast-evolving domains as smart energy markets, it is necessary to develop and adapt existing pricing methods within changing market dynamics, taking into account individual user preferences and objectives with respect to the decision context. The Real-Time Prices offered in the experiment are electricity retail prices based upon the Dutch spot wholesale electricity market, APX [36] and are forwarded to the participating households on a day-ahead basis. The TOU prices vary between a peak period and an off-peak period, depending on the  
Figure 1: Information stream overview with respect to Home Energy Management Systems and communication with the central utility server in relation with electricity market landscape. month-ahead forward price for electricity and a risk premium according peak and off-peak. Both tariffs are supplemented with a fixed number for surcharges, namely balancing, sustainability guarantees and energy taxes. Prior to the start of the experiment, electricity home energy management devices are installed in all households. As such, households gained access to real-time energy consumption and electricity prices through a web-based dashboard for Notebooks, Smartphones and Tablets. This home energy management system thus allows customers to get a better, real-time understanding of their energy-related activities. A tariff overview allows for the proper review of past household electricity usage behavior, electricity prices and final cost of electricity usage throughout the day. The web application displays usage to the users as the net electricity consumption of a household. Negative usage values indicate that the user generates more electricity than consumed. The respective negative values in the cost column indicate the discount granted to the household for the next electricity bill. A visualization of the web application can be found in Figure 2.  
The home energy management system allows households to get a better overview of past usage behavior and future outlook in the form of next day prices by a dashboard visualizing consumption and production next to general functions, such as profile, metering, messages and a financial overview. Figure 2: Visualization of Home Energy Management System in natural experiment—Translated from Dutch. (**a**) displays an electricity tariff overview on mobile devices and (**b**) a household electricity usage dashboard. The users can examine the respective load profiles for electricity and gas for any given point in the past on daily, weekly or monthly levels. Additionally, users can compare their load profile with the load profile of comparable households in the Netherlands. The households have the option of exporting their usage data from the dashboard for a more in-depth analysis. The hourly electricity tariffs are communicated on a day-ahead basis via the home energy management system.