ALBANY — A third of the Assembly is urging Gov. Andrew Cuomo to put at least $2 billion into an energy efficiency program focused on improving some 800,000 buildings across the state.

Fifty lawmakers in the chamber have signed on to a letter released Wednesday calling for the funds to be made available in the upcoming 2020-21 fiscal year, through the Clean Energy Fund or any other appropriate funding source, while the Climate Action Council drafts its plan — which they say could take three years.

“$2 billion is less than 2 percent of all state funds in New York,” Assemblywoman Barbara Lifton said at a press conference on Wednesday. “It’s not too much for us to spend on this truly existential threat that we're facing and New York, I hope, wants to lead and lead in an even stronger way than we are.”

The Clean Energy Fund money comes from electric customers and is a $5 billion, 10-year program overseen by NYSERDA. The goal was to lower costs of energy efficiency-related surcharges on customer bills and use the money to transform markets and spur technological innovation, leveraging private investments and moving away from traditional grants or incentive programs that directly fund projects.

Walter Hang, the founder of the environmental group Toxics Targeting, pointed to New York’s On-Bill Recovery Loans as a potentially powerful tool, during the press conference with Lifton. Hang estimates the average utility bill in New York is around $2,500 per year and a single-family home could be retrofit to be energy efficient for roughly $5,000.

The program would allow for the state and the homeowner to split the cost evenly. The energy efficiency measures could save a homeowner $800 annually and could be as simple as installing programmable thermostats, Hang said.

According to the American Council for an Energy-Efficient Economy, improving efficiency in buildings could reduce their energy consumption by 30 to 40 percent. This would not only save homeowners and business owners in utility costs, but also decrease New York’s reliance on fossil fuels — which accounts for nearly half of the state’s consumption. Renewable energy accounts for roughly 4 percent.

The letter points to Cuomo’s attempt of a similar proposal in 2016 to make homes and business more energy efficient by 2020. Hang says the proposal did not come to fruition.

Earlier this year, Cuomo announced $2 billion in funding for energy efficiency and building electrification initiatives.