Before we can understand how to get to Net Zero energy use, we must first understand just what “energy” we actually use. People talk about “energy” and “electricity” as if they are the same thing — they are NOT. And, even our entire nation has embarked on reducing fossil fuels from electricity generation, but electricity is only a small portion of the energy we use.
Exactly what energy do we use? Let’s start by just focusing on buildings. The graphic at the right shows a typical energy breakdown for a residential or commercial building. Some energy is used for heating and cooling (HVAC), some for hot water (DHW), some for lighting, and some for all other electrical items (“plug loads”). It doesn’t matter if we are talking about a house, an apartment, or an office building, this same graphic applies just with the various usage components being smaller or larger. For example, some buildings using more HVAC (e.g., older buildings), some more DHW (e.g., restaurants), and some more electricity (e.g., data centers).
Now consider the graphic at the left which shows which energy loads are “thermal” and which are strictly “electric”. HVAC and DHW are “thermal” loads — sometimes they are handled by fuels (oil/gas/propane) and sometimes by electricity. The “electric ” loads are those that can only be served by electricity.
The graphic clearly shows that thermal loads (HVAC and DHW) are the primary energy loads in most of our buildings. This is an important and necessary understanding before we can learn how to intelligently move toward Net Zero.
Moving to Net Zero
The graphic at the right shows how this “typical” building is converted to Net Zero. Geothermal Heat Pumps (GHP – see NZ Technologies page) are the Renewable Energy (RE) technology used for HVAC and DHW. GHP provide for about 75% of the Thermal Loads using the solar energy absorbed by the ground plus the waste heat from the previous season’s cooling that was stored in the ground. This thermal energy (in green) from the earth is “Free” — nothing is paid for that energy. The remaining HVAC/DHW energy shown is for the electricity needed to run the GHP equipment.