Your apartment's heating is provided by way of FCUs (fan coil units) which contain electric heating elements. Living areas with just one FCU vent will typically have a 3kW heating element, and larger living areas typically have two FCUs with a total heating power of 5kW. FCUs serving bedroom areas typically have heating elements of 2 or 3kW, depending on how many rooms the FCU serves. For cooling see here.
When you turn the Baxi controller to the 'on' position, and have the dial set to the right of centre (see photo), the FCU(s) will begin blowing ambient air, and then the heating element(s) will come on, so that warm air is circulated.
A 3kW FCU will therefore use three units of electricity per hour (plus c200 watts to run the fan), and 5kW FCUs five units of electricity. This is charged to your apartment's electricity bill: ie, residents pay for their own heating usage. This is different to cooling, which is communally provided and the costs of which form part of your service charge. Please see this spreadsheet for details of the kW rating of the heating elements located within your apartment. This will help you understand how much electricity you use when heating your apartment.
If you are also using the skirting heaters (which are controlled by one of your Baxi units, typically the control serving the bedrooms), they typically use 200 watts per metre. Depending on the size of your apartment you could have between 2kW-5kW of skirting heating if all of the panels are on (ie, if the fuse spurs do not have switches enabling you to turn off the panel in a specific room).
If you have the dial set to a point just past the centre (as in the photo), the heating element(s) will switch off once a temperature of c.21C has been reached. The FCU(s) will continue to circulate air, but it will be at the ambient temperature. Once the Baxi controller senses that the temperature has fallen below 21C, the heating elements will come back on. If set to the left of centre, you will activate the cooling.
If you set the dial on the Baxi unit to the far right, the heating element(s) will remain on all the time that the Baxi control is on the 'on' position. Unless this is your intention, it is advisable to set the Baxi controller to the right of centre, so that the heating will come on and off depending on whether the temperature (at the Baxi controller) has reached c.21C.
Other sources of electric heating in your apartment include underfloor heating in the master bedroom ensuite, and heated towel rails. In addition, there is electrical tape (trace heating) on the hot water pipes located within your apartment that use electricity to ensure that there is near-instant hot water available when you turn on your tap.
More information about the FCUs can be found in the Information section.