In a recent study by the American Council for an Energy-Efficient Economy (ACEEE), window-mounted heat pumps have emerged as a cost-effective solution for decarbonizing heating in large multifamily buildings. According to Steven Nadel, ACEEE’s executive director, these innovative heat pumps, particularly the window-mounted models, offer a scalable and economical approach to achieve full decarbonization in apartment buildings. While biofuels have been considered, they fall short in delivering the necessary deep emissions cuts at the required scale.
The study recommends building owners exploring window-mounted heat pumps, mini-split systems, and central air-to-water heat pumps for decarbonization efforts. The choice among these options should be based on the specific characteristics of the building. Window heat pumps were identified as the most cost-effective solution, with an average cost of around $14,500 per apartment for both purchase and operation over 24 years. Comparatively, central air-to-water heat pumps cost approximately $22,000 per apartment, while mini-split heat pumps come in slightly higher at just over $25,000.
A new variant of window heat pumps has been introduced in recent years, designed to sit on a windowsill without obstructing light and can be connected to a standard 120-volt outlet. These models, especially those for cold climates, can operate efficiently even at temperatures as low as zero degrees Fahrenheit without the need for backup heating. The report highlights that the New York City Housing Authority has already integrated these new window heat pumps into its properties, with other cities beginning their initial deployments. Similarly, central air-to-water heat pumps are gaining traction in the U.S. market, with initial installations in cities like New York and Boston.
The study also evaluated the feasibility of burning biofuels for residential heating, including biomethane boilers, bio-oil boilers, and central air-to-water heat pumps with biofuel backup. While these options come at costs ranging from $21,000 to $23,000, they are unable to fully decarbonize building heat due to significant carbon emissions associated with biofuels. Moreover, the limited availability of these fuels poses a practical challenge for widespread adoption. Notably, the research found no instances of boilers entirely powered by biofuels.
While much focus has been on electrifying heating systems in single-family homes, there is a substantial number of multifamily buildings in the U.S. that also require attention. ACEEE’s report concentrates on the 36 percent of apartments in large buildings with central heating systems, highlighting the need for policies that promote energy efficiency measures like enhanced insulation and building envelope upgrades. Recommendations include implementing electric rates that incentivize heat pump usage based on service costs, providing financial incentives for electrification and efficiency enhancements, and establishing a carbon pricing mechanism to account for the environmental impact of fossil fuel combustion and fund heat pump incentives.
The analysis conducted by ACEEE was based on a dataset comprising 533 apartments in buildings with five or more units across the United States, sourced from the U.S. Energy Information Administration’s Residential Energy Consumption Survey. By leveraging apartment-specific energy usage and cost data, the study compared various low-carbon heating options to assess their viability in promoting decarbonization efforts for large apartment buildings.
Tags: biofuels
Read more on dailyenergyinsider.com