Source Energy

It takes energy to get energy. If you heat with wood, the wood embodies the gasoline used to run the chainsaw and fuel the delivery truck. If you use electricity from a natural gas fired generating plant, your electricity embodies the energy used to get the gas out of the ground and transport it to the power plant, the energy lost in running the power plant, and the energy lost during  transmission to your building. For electricity from the power grid, the multiplier used to convert site energy – the electricity that passes through your meter – to source energy – which includes the embodied energy foot print of your electricity – is often around 3. Passive house energy modeling software uses 2.7 as a general assumption. This means that a typical electricity consumer uses about three kilowatt hours worth of energy for every one kilowatt hour that passes through the meter. In this example, in terms of space or water heating, the bulk of those losses could be avoided by burning natural gas in an efficient furnace or water heater on site. However, committing to fossil fuel fired appliances means committing to fossil fuel. Very high-efficiency electrically-powered heating equipment and systems respond to this dilemma. Resistance heaters, such as electric baseboards, are very inefficient from a source energy perspective.  A better option for heating with electricity, which can be a renewable resource, is to use a heat pump with performance efficiencies high enough to make up for the losses inherent to our electricity supply. .