“A maze for developers to navigate.” That’s how Tamara Small, CEO of NAIOP Massachusetts, described efforts by legislators in her state to set increasingly higher mandates for decarbonizing buildings.

The scenario is an increasingly common one. In Maryland, state and local governments are also debating measures to increase the energy efficiency of buildings and lower, or ban, fossil fuel use in buildings.

Concerned about climate change, the Massachusetts legislature passed two major bills focused on adaptation and mitigation more than a decade ago. The Global Warming Solutions Act set a goal of an 80 percent reduction in greenhouse gas (GHG) emissions (compared to 1990 levels) by 2050. That jumpstarted new review processes for real estate developments and compelled Massachusetts to adopt one of the most efficient energy codes in the country. Meanwhile, the Green Communities Act offered financial incentives to municipalities that implemented certain GHG-reduction measures, including a stretch energy code.

Within the past year, the drive to lower GHG emissions has gotten more complicated. The Massachusetts House and Senate are currently debating bills that would increase the 2050 goal to a 100 percent reduction in GHG emissions, create a carbon tax and establish a third energy code for the state, namely a net zero stretch code.

Local governments have initiated their own decarbonizing efforts.

The mayor of Boston announced plans to make the city carbon-free by 2050 and “embarked on a very aggressive and ambitious plan that looks at both existing buildings and developments…and asks developers how they can get to net zero,” Small said.

The city expects to roll out policies next spring to support its carbon-free goal. In planning sessions, city officials have acknowledged “that a 20- to 30-story office building to be recognized as net zero would require a mix of extraordinary efficiency plus onsite renewables and offsite renewable credits,” she said.

Meanwhile, eight Massachusetts communities have started debating fossil fuel bans that would almost immediately prohibit the installation of oil- or gas-fired heating/cooling equipment in new buildings. Such measures “would be extraordinarily detrimental to any projects going through the permitting process. This would be a nail in the coffin for many projects. So that is something that we are continuing to watch with alarm,” Small said.

The state’s attorney general struck down the first fossil fuel ban passed by a municipality. However, the new, widespread focus on reducing GHG emissions through electrification has troubled many people in the development community.

“Tomorrow, if you were to build a building with electrification, you would have really high electric bills for tenants. It’s by no means the most efficient way to heat and cool a building,” Small said. “There’s going to be a time when fossil fuels are no longer needed, but we’re not there yet. To put a ban on fossil fuel now is to basically ban development. That’s really, really concerning for us.”