Introduction:
In this demo case CITIES has shown that CO2 emissions can be reduced by at least 10 per cent by heating the water in the indoor swimming pools when the electricity is generated by wind turbines and stopping it when the electricity comes from sources with a higher carbon footprint. This will also make itself felt on the electricity bill, which can usually be cut by EUR 1,400-2,000 (DKK 10-15,000). 

Method:
The reductions (CO2 emissions and/or costs) are achieved by a CITIES-developed box in the holiday homes communicating with a central server established with ENFOR A/S that calculates the optimal time for heating the water.

This optimization is achieved in a partnership with Tomorrow a/s in which forecasts of the CO2 levels in the electricity are obtained for the coming days, which are compared with an ENFOR-based prediction of heating needs. The predictions are based on weather forecasts, information about temperature requirements, and other data which are downloaded directly from a server with booking information at NOVASOL. The central server at ENFOR thus gives the individual house notification to start the heat pump or electric cartridge.