How can we reduce our housing's CO2 emissions?
Heating is the first cause of energy consumption of western homes. The first thing to do is therefore to improve heat isolation, to avoid wasting energy. If that is not possible, the best attitude is to waste not, including in how we heat our homes. That includes not heating, when we are out. It also includes keeping the heating down during the night, with a target temperature not higher than 19 °C during the day and 16 °C during the night.
Household appliances are also responsible for a large share of energy expenditure. It's worth using less energy consuming appliances, and using them less frequently. It is also worth moving fridges and freezers away from heat sources (ovens, radiators...). And choosing the eco-friendly modes on dish-washers, washing-machines, clothes dryers and the like.
Lastly, remember to unplug any electrical appliance you are not using. There's no point in offsetting CO2 emissions if you don't first reduce your energy expenditure.