This paper considers the technical and economical feasibility of the introduction of automated demand response from domestic smart appliances in a European setting as a means to create a significant amount of regulating power. Simplified power-time flexibility models for appliances are introduced on which generic economic simulations can be based. These simulations permit a good indication of the economic value that can be attained as a function of model parameters. This shows that classical load shifting of washing appliances creates sufficient value in the day-ahead market to justify investments in smart energy control services. Cooling appliances create significant value on the balance market and while full scale deployment would lead to significant price erosion in today's market, it could accommodate additional unbalance caused future sustainable generation. The scale of domestic demand response resources can be quantified in two simple parameters: regulation power and storage capacity. For the Dutch situation these are 700 MW, equivalent to 5% of average national power consumption and 5 GWh storage: around 20 minutes of average national power consumption. Smart appliances can deliver a 100% efficient and CO2 friendly complement to the unpredictability of e.g., large scale wind power as planned in large parts of Europe in 10 to 15 years.