We understand from your question that your electrical installation is not designed to operate at 240 volts. In fact, the vast majority of our residential customers’ electrical installations are at 120/240 V, and not 110/220 V, which is an obsolete voltage. Your heating system, water heater, stove and dryer are all designed to operate at 240 volts, while small appliances (electronics, lighting, etc.) operate at 120 volts.
With regards to efficiency, there is no correlation between voltage and an appliance’s power. It is therefore incorrect to assume that a 240-V installation is more efficient than a 120-V installation. Keep in mind that a poorly maintained installation is dangerous, no matter what the supply voltage.
If you would like to upgrade your installation to 120/240 V, please contact a master electrician. Note that this work would be at your expense.