A man stands in front of a heat pump designed to capture and recycle energy from the sewer.
Technical Summary

High-Efficiency Heat Pumps

Project Drawdown defines high-efficiency heat pumps as high-efficiency[1] electrical devices that harvest latent heat from ambient sources such as the ground, air, or water for use in the conditioned space via the compression and expansion of a working fluid (refrigerant). This solution replaces new and existing conventional heating, ventilation, and air conditioning (HVAC) systems, including gas- and oil-fired furnaces, gas- and oil-fired boilers, low-efficiency air conditioners of all types (room-based, window units, central), electric resistance furnaces, and electric resistance unit heaters in both residential and commercial applications.

Methodology

Total Addressable Market

The total addressable market for heat pumps is based on estimated supply for commercial and residential building space-heating in terawatt-hours from 2020 to 2050, derived from the International Energy Agency’s (IEA’s) data. Current adoption[2] of high-efficiency heat pumps was estimated to be 3 percent of the market for delivered heat.

Adoption Scenarios

Impacts of increased adoption of heat pumps from 2020 to 2050 were generated based on two growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels.

Data on global adoption scenarios of heat pumps remains sparse. It is estimated that improved HVAC equipment can reduce the overall demand for space heating and cooling 25–70 percent. As one of the most efficient of those HVAC systems, heat pumps generally, and high-efficiency heat pumps specifically, must play a key role in that. The scenarios below are aligned to the IEA scenarios with more explicitly aggressive and improving efficiencies (seasonal coefficients of performance, SCOPs[3]). Aggressive growth of high-efficiency heat pumps can be expected globally as prices continue to decrease.

For heat pumps, two scenarios for heat delivery (as oppose to cooling) were developed:

  • Scenario 1: Using the IEA’s 2017 ETP 2DS Scenario, we project the total demand for all heat pumps, and then apply an assumed linearly increasing SCOP from 2.9 (average today) to 3.5 in 2060.
  • Scenario 2: Using the IEA’s 2017 ETP B2DS Scenario, we project the total demand for all heat pumps, and then apply an assumed linearly increasing SCOP from 2.9 (average today) to 4.3 in 2060.

Emissions Model

It is assumed that high-efficiency heat pumps replace coal, gas, and oil boilers as well as electric resistance heaters in a ratio defined by their share of total heating final energy based on IEA data for the globe. For every terawatt-hour (therm) of delivered heat produced by high-efficiency heat pumps, an equivalent amount of energy would be avoided from the heating systems mentioned above. While the replacement of these high-emissions technologies for electricity-based heat pumps will increase the overall usage of electricity, overall energy savings are achieved through reduced direct fuel combustion and an increase in efficiency in electricity use. Grid and fuel emissions are included and emission factors come from the Intergovernmental Panel on Climate Change (IPCC) data.

Financial Model

The first costs of high efficiency heat pumps are estimated at US$9911 per installation unit, compared to a weighted cost of US$7915 per unit for conventional HVAC systems.[4] Costs are equal to the sum of the retail price of the equipment and any material or labor costs necessary for installation. The reported installation costs for conventional technologies are weighted by residential and commercial applications, at 75 and 25 percent, respectively. The source for these values comes from the U.S. Department of Energy (DoE), U.S. Energy Information Administration (EIA), IEA, and the International Renewable Energy Agency (IRENA). A set of published learning rate data for air conditioning units was collected and use with the assumption that air conditioning units are sufficiently close enough to heat pumps.

Operating costs include building heating energy (fuel and electricity). Fuel and electricity prices were averaged over 2007–2018.

Integration

The heat pumps solution was integrated with others in the Buildings Sector by first prioritizing all solutions according to the point of impact on building energy usage. This meant that building envelope solutions like insulation were first, building systems like building automation systems were second, and building applications like heat pumps were last.[5] The impact on building energy demand was calculated for highest-priority solutions, and energy-related heat pumps input values were reduced to represent the impact of higher building envelope solutions.

Results

Project Drawdown’s Scenario 1 adoption of heat pumps avoids over 4.2 gigatons of carbon dioxide-equivalent greenhouse gas emissions by 2050. In addition, implementing heat pumps across the new and existing building stock requires only a marginal investment of US$78 billion more than the Reference Scenario, but saves more than US$1.1 trillion in operating costs over 2020–2050. The Scenario 2 shows 9.3 gigatons and US$2.5 trillion in lifetime operating costs avoided for US$117 billion in net costs.

Discussion

Buildings consume over 31 percent of global final energy use and account for 8 percent of direct energy-related carbon dioxide emissions, putting them among the largest end-use sectors globally. Energy for heating and cooling is estimated to account for over half of the energy consumption in buildings. With an increasing population and rising incomes, it is estimated that the global number of households could grow by over 65 percent and the floor area of commercial and institutional buildings by nearly 200 percent by 2050. In the absence of aggressive policy action for reduced energy consumption, the global cooling and heating energy demand is expected to increase substantially.

Heat pumps can serve as an efficient and sustainable solution to indoor space conditioning with high-efficiency. Retrofitting existing HVAC systems with state-of-the-art heat pump equipment is a viable option for consumers looking for ways to reduce building energy costs, without having to make major investments or structural changes to the building. This may require modifications or additions to the existing system, but offers significant energy savings. In some cases, the new high-efficiency equipment is actually cheaper to install than less efficient equipment.

Note: August 2021 corrections appear in boldface.

[1] High-efficiency heat pumps are HVAC systems for heating, cooling, and ventilation with a seasonal coefficient of performance (SCOP for heating) of at least 3.5 Wh/Wh (heating seasonal performance factor > 12 BTU/Wh) and seasonal energy efficiency ratio (SEER for cooling) of at least 5.9 Wh/Wh (20 BTU/Wh), depending on installation (split/packaged).

[2] Current adoption is defined as the amount of functional demand supplied by the solution in 2018. This study uses 2014 as the base year.

[3] The SCOP measures the efficiency of a heat pump under typical usage conditions

[4] All monetary values are presented in 2014 US$.

[5] Although we used the term “priority,” we do not mean to say that any solution was of greater importance than any other, but rather that for estimating total impact of all building solutions, we simply applied the impacts of some solutions before others, and used the output energy demand after application of a higher-priority solution as the energy demand input to a lower-priority solution.