Heat pumps are ready for their day

Air-source heat pump at Phoenicia Library. (Photo by Violet Snow)

“There’s heat in everything — ground, air, water,” said Donovan Gordon, Director of Clean Heating and Cooling at NYSERDA (New York State Energy Research and Development Authority). Although it seems counterintuitive, air-source heat pumps draw heat even from winter air, and some structures in our area already rely them for both heating and cooling, including the Golden Notebook bookstore, a model green home in Woodstock, and the Phoenicia Library.

As the state works to curb dependence on fossil fuels, NYSERDA has embraced heat pumps, which run on electricity, as a means of addressing climate change. Rebate incentives are available from NYSERDA and local utilities, with the goal of making conversion of a home to heat pump technology both practical and affordable. 

Advertisement

New York State’s Green New Deal, passed this April, mandates 100 percent clean power by 2040, with substantial investment in large-scale renewable energy projects upstate and offshore wind generation near the New York City port. Thus devices powered by electricity will increasingly run on clean energy, at least within the state. In addition to promoting the switch to electric vehicles, NYSERDA is encouraging residents and businesses to install heat pumps, to either replace or supplement conventional furnaces.

Instead of burning fuel, a heat pump transfers heat from one place to another. There are two common types: ground-source and air-source. Below five feet from the surface, the ground remains around 55 degrees, even in freezing weather. (A week of subzero temperatures may drive this line to seven feet down.) A heat pump uses a compressor and refrigerant chemicals to draw heat from the ground and into the house. In summer, heat is extracted from the building and sent into the ground. However, installation of a ground-source system is expensive and includes the drilling of bore holes and placement of sub-surface piping, more practical for new construction than for conversion of existing homes.

Air-source pumps can draw heat from air as cold as five degrees. “When the temperature gets down to minus five, a pump will operate more like an electric resistance heater,” said Gordon. “It’s not quite as efficient, but when you look at the weather data, that’s four or five days per year in our area.” While less efficient than ground-source technology, air-source pumps are more efficient than furnaces run by fossil fuels, and they also function as air conditioners in summer, drawing heat out of the building. An air-source pump can either replace a regular furnace, heating the entire house, or homeowners can purchase a “ductless minisplit,” a unit that may be mounted on a floor, wall, or ceiling. In either case, piping and wiring connect to equipment out outside the house for extraction and transfer of heat. 

A minisplit can handle about 750 square feet, which could address two rooms on an open floor plan. Several units would be required to address the whole house. If building an addition, a homeowner might buy a single unit to heat it, or they might purchase one for a frequently used room that tends to be cold in winter

The cost of a minisplit is about $3000 to $4000 per unit. Local utilities and NYSERDA offer incentives that can reduce the cost by up to $1000. While utilities initially balked at accommodating renewable energy, which threatened their profits, they have come to embrace heat pumps. “A utility designs systems for summer peaks when everyone has their a/c on,” said Gordon. “Having efficient cooling reduces the demand for electricity on those hot days, and heat pumps are more efficient than regular air conditioners. In winter, switching to electricity increases the utility’s revenue.”

After the Phoenicia Library burned in 2010, the renovated building incorporated air-source heat pumps to replace the old oil burner. Trustees estimate the annual energy savings to be 85 percent.

To facilitate the transition to heat pumps, NYSERDA is educating consumers and contractors. Plans are in the works for outreach events at town halls and libraries, where residents can learn about the new technologies. Reduced-cost energy efficiency improvement packages will be available for sealing and insulating the home’s exterior. The property will then be ready for a smaller, lower-cost system when the homeowner is ready to upgrade to a heat pump.

A pilot program has been designed to train contractors in planning for heat pump installation by evaluating a property, doing the work to improve the building envelope, and estimating the heating and cooling needs. Contractors will also be able to recommend the most appropriate type of system, based on the homeowner’s preferences and guidance from Northeast Energy Efficiency Partnerships, a regional nonprofit that supports state efficiency policies and programs.   

“Most residents don’t know much about pumps or who installs them,” said Gordon, “so it helps to know contractors who have been vetted for the quality of their work.”

Melissa Everett of Sustainable Hudson Valley commented, “If we are going to have a chance of containing climate catastrophe, we need to shift quickly off fossil fuels. Electricity is far more efficient than combustion for heating, cooling and transportation. But what we need is a massive shift by a large majority of people.”

For more information, see https://www.nyserda.ny.gov. 


The role of solar

Solar panels have traditionally provided homes with electricity but not heat. Now, with efficient electric-powered heat pumps, people can use solar arrays to heat their homes.

At the same time, battery technology is becoming more effective and less expensive, allowing energy from solar panels to be stored for use when the sun is not out. “Now thermal storage is even being looked at for large-scale commercial applications,” said NYSERDA’s Donovan Gordon.

Seth Leitner of Sustainable Hudson Valley has augmented his solar array with two Tesla powerwalls, bearing battery banks. His family’s summer energy bill went down from $519 to $80, as the washer, dryer, stove, and electronic devices drew power from the walls at night. “We’re not using the grid,” Leitner said.

At this point powerwalls are still pricy, with a pair going for $14,000, but costs are sure to drop over the next few years, as the technology improves and other battery options come on the market.

Post Your Thoughts