By Eric McDonald,
Director, Testing & Infrastructure Development
By 2050, both Governor Whitmer and President Biden hope to achieve carbon neutrality in Michigan and the United States, respectively. To become carbon neutral, Michigan and the U.S. must balance carbon dioxide absorption with the reduction or elimination of carbon dioxide emissions until achieving net zero. Accomplishing these goals will require leveraging new and existing technologies to meet our energy needs.
Furnaces for heating are a major source of emissions and account for up to 40% of greenhouse gas emissions, mostly from natural gas and fuel oil furnaces. To move toward carbon neutrality, we must decrease or eliminate natural gas and fuel oil furnaces and increase the use of electric furnace heating. Though the current electric grid is mostly supplied from natural gas and fossil fuel sources, the expectation is that, due to demand and regulation, electricity generators will have to convert to renewable and zero-carbon sources of electricity, eventually rendering electric heating a carbon-neutral option.
People may be familiar with electric baseboard heat and electric forced-air furnaces. But the efficacy of electric baseboard heat is low compared to gas forced-air furnaces and gas or fuel oil boilers. Electric furnaces, though less expensive to purchase and install, cost 300% more to operate than gas-fired furnaces and boilers. So how can we move toward electric heating?
One answer has been around for almost 80 years — the electric heat pump. This technology is gaining interest for its efficacy and energy efficiency. While there are water source heat pumps and air source heat pumps, here we examine only air source heat pumps because they can be readily added or retrofitted to existing forced-air furnaces.
A heat pump is similar to an air conditioner, but is also able to run in reverse and heat the air. Similar to an air conditioner, in hot weather a heat pump removes heat from a room and transfers the heat outside. In cold weather, a heat pump removes heat from the cold outdoor air and transfers the heat into the indoor room. Heat pumps are more efficient than furnaces or boilers. A furnace or boiler generates heat to be moved, but a heat pump only moves the heat in a room. Because of this, a heat pump produces four units of heat for each unit of energy used, while a gas furnace produces only one unit of heat for each unit of energy used.
That said, heat pumps from some manufacturers do have a drawback. These heat pumps lag in heating effectively at outdoor temperatures lower than 0°F, making them unsuitable for use in northern climates with extreme winters, such as the Upper and Upper Lower Peninsulas of Michigan, Minnesota and Wisconsin. But in warmer areas, such as moderate southern climates, heat pumps have been used as a heating source for many years.
Heating performance in extreme cold climates will hinder smooth adoption of heat pump use across the country. But as interest for heat pump heating increases in northern states, manufacturers are pushing their technology to perform effectively at lower subzero temperatures. Many heat pump manufacturers now produce equipment that heats well at temperatures of 15°F below zero. This is possible via technologies such as inverter-driven compressors, variable refrigerant flow, heat/energy recovery and even simple solutions like placing the outdoor unit (condenser) inside the building. As we strive to reach carbon neutrality and demand for electric heat increases, educating consumers and installers on the greater capabilities of heat pumps will be necessary for the adoption and success of this established heating technology.