Natural gas-powered HVAC systems and "net-zero" building codes are among the chief bones of contention in Massachusetts' carbon emissions debate.

By the year 2050, the Baker administration envisions 80 percent of Massachusetts homes will be heated and cooled with electric heat pumps, and the statewide electrical infrastructure will be able to handle two and a half times more load than in 2020.

Those are some of the key benchmarks in a new climate and clean energy plan Gov. Charlie Baker’s secretariat published Dec. 21, outlining sector-specific emissions reduction targets and policy steps that will help Massachusetts achieve the legally required target of achieving net-zero statewide carbon emissions by the middle of the century.

The 2050 plan, which the Baker administration released on its way out the door of state government, seeks to formalize and expand a range of tactics already in play, leaning heavily on electrifying the transportation and building sectors and expanding clean energy sources such as offshore wind.

Energy and Environmental Affairs Secretary Beth Card said the 192-page document “represents the commonwealth’s comprehensive and aggressive plan to achieve net-zero cost effectively and equitably.”

On the building front, the plan calls for creation of what Card called a statewide “benchmarking and labeling program” that would make more information public about building emissions, plus development of a “statewide climate finance accelerator” to drive more investments in buildings seeking to eliminate carbon emissions.

It also implements recommendations of the Commission on Clean Heat that Baker created via executive order. That panel published its final report last month, recommending steps such as development of a “clean heat standard” to incentivize building electrification and cleaner heating technology.

Another area of focus is on land conservation. The administration set a target of ensuring that at least 40 percent of lands and waters in Massachusetts are permanently conserved and shielded from development by 2050, an increase over the 27 percent that the plan says are now “legally protected in perpetuity.”

Card said the plan also calls for crafting policies to limit the clearing of forests for solar developments and for planting at least 64,400 acres of trees in the coming decades.

“Achieving net-zero will require significant changes in how land is used throughout the commonwealth, including energy and transportation infrastructure, housing development and land conservation,” Card said.

State law requires Massachusetts to cut total greenhouse gas emissions at least 85 percent below 1990 levels by 2050, plus offset any remaining emissions by removing an equal or greater amount of carbon dioxide or its equivalent from the atmosphere. The Baker administration plan sets specific sublimits for 2050 emission reductions for several sectors: 86 percent in transportation, 95 percent in residential heating and cooling, 92 percent in commercial and industrial heating and cooling, 93 percent in electric power and 72 percent in natural gas distribution and service.

Those sublimits are slightly stricter than they would need to be to achieve the 85 percent economy-wide reduction necessary to hit net-zero emissions, and the administration said that approach offers “margins for error.”

“With climate impacts already at our doorsteps, now is the time to take action for the future,” said Conservation Law Foundation Vice President Caitlin Peale Sloan. “This plan is on the right track, especially when it comes to phasing out fossil fuels in our homes and on our roads. But we need to do more on environmental justice to make sure that no communities are left behind in the years ahead.”

Energy Undersecretary Judy Chang pitched the new 2050 plan as a longer-term complement to the Baker administration’s 2025 and 2030 plan, saying it “really explores all the other trajectory beyond 2030” necessary to achieve net-zero emissions by the century’s midpoint.

Card said the Baker administration modeled its 2050 plan “to be flexible enough to respond” to new technological developments, federal policies and global trends, infrastructure siting or any other changes that could emerge in the next 27-plus years.

“Really, this plan is a comprehensive sort of capture of what we think needs to happen next,” Card said.

Last week’s announcements land about two weeks before Baker and his energy and environmental affairs secretariat will give way to Gov.-elect Maura Healey, who plans a staff shake-up that involves hiring U.S. Environmental Protection Agency Principal Deputy General Counsel Melissa Hoffer as a new Cabinet-level climate chief.