ReduceOurEnergy.com

During this project, the electrical energy being consumed by a building is being measured. These measurements are given in terms of Watt-Hours or kiloWatt-Hours (where 1 kiloWatt = 1000 Watts). If 1 kiloWatt is being consumed (eg. by a vacuum cleaner) for 1 hour continuously, then 1 kiloWatt-Hour will have been counted. Similarly, if a device such as a kettle, using 2 kiloWatts of electricity is on for half an hour continuously, then 1 kiloWatt-Hour will be counted. The abbreviation kWh is used to signify a kiloWatt-Hour.

The average home uses approximately 5,300 kWh per year (and with 8,760 hours in a year, this means an average usage of 605 watts all the time).
The price paid for electricity is often quoted as pence per kWh and currently in Ireland the price per kWh is approximately 17 cent.
A handy rule of thumb is that for a device which is powered on all the time, for every 1 Watt it uses, that will amount 1.50 Euro per year.
Ireland consumes approximately 30,000,000,000 kWh per year. (Equivalent to 3,400,000 kW, or 3.4 GW, all the time).

Yesterday, the total amount of energy consumed by all participants was 1 kWh, which equates to 0.40 kg of CO2
On average, Ireland uses 82,192,000 kWh per day, so the participants collectively accounted for 0.000001 percent of Ireland's total electricity usage yesterday.

Where that electricity comes from:

Sources:
1. http://www.esb.ie/esbcustomersupply/residential/price-plans/index.jsp
2. http://www.seai.ie/Publications/Statistics_Publications/SEI_Renewable_Energy_2010_Update/RE_in_Ire_2010update.pdf
3. http://www.eirgrid.com/operations/systemperformancedata/systemdemand/