Above: Solar Photovoltaic systems on top of Greenline Homes Development at 6106-6112 South Ellis.

A Net Zero Energy home requires a renewable energy source to offset the energy used by the home. For decades, solar photovoltaic panels, commonly referred to as simply solar panels, have been the most popular way to produce renewable energy at home. The concept is simple: make electricity on the roof and use that power for activities like lighting, heating, air conditioning, and refrigeration.

This may seem very simple until you learn that the technology to heat homes in cold climates has typically used natural gas as the primary fuel. Cheap and readily available gas has driven the development of gas powered heating equipment that heat homes very efficiently. Unfortunately, natural gas cannot be made at home.  

So, how do we heat a home efficiently using electricity?  A few years ago, we witnessed the introduction of a cold-weather, air-to-air heat pump. This is an electrical appliance, not all that different than the venerable central air conditioner. In fact, a central air conditioner is an air-to-air heat pump that moves heat from inside your home to the outside, cooling your home. This new class of cold-weather heat pumps are capable of operating in reverse; extracting heat from outside air that is down to -15 degrees F and moving that derived heat, via refrigeration technology, to the inside your home.  In the summer, they reverse their cycle and cool your home by moving heat to the outside of the home. They are much more efficient at heating than the older class of resistive electrical heating appliances, such as electric baseboards or electric furnaces, using only a fraction of the power traditionally required to heat a home with electricity.

Greenline Homes saw an opportunity to combine solar photovoltaic technology and cold weather heat pumps to directly offset carbon generated by heating homes in Chicago's climate.  

Above: Photo of a Cold Weather Air to Air Heat Pump installed at 6118 South Langley.  This unit moves heat using refrigeration technology, extracting sufficient heat from outside air down to -15 degrees F to heat the home.  In the summer, the unit reverses the flow of refrigeration, allowing the same unit to cool the home.Above:  Indoor head unit installed at 6118 South Langley.  This unit heats or cools the interior of the home and is the most efficient way to heat an open concept space with electricity.  It's tied to the outdoor unit by insulated refrigeration lines that allow it to move heat.  Below:  Photo of another Mitsubishi indoor unit, this one ducted to heat bedrooms, great for sending heat through ductwork.  To the Right in the photo is a hot water heater that also uses a heat pump to electrically heat water with exceptional efficiency.