LL97 Penalties Aren’t What Most Calculators Show

The $268/Tonne Problem

NYC Local Law 97 is one of the most aggressive building performance standards in the United States. Buildings larger than 25,000 square feet can be fined $268 per metric tonne of CO₂e above their annual emissions limit.

After reviewing hundreds of LL97 estimates, I noticed the same issue repeatedly appearing in reports and calculators: the carbon math is often wrong.

Most tools use the EPA eGRID electricity emissions factor for NYISO ( 0.000371 tCO₂e/kWh ).

LL97 does not use EPA eGRID values.

That difference alone can completely change a building’s projected penalties.

What LL97 Actually Uses

According to 1 RCNY §103-14 Table 1 , the official LL97 emissions coefficients are:

Fuel Source LL97 Coefficient EPA eGRID (NYISO) Difference

Electricity 0.000288962 tCO₂e/kWh 0.000371 tCO₂e/kWh -22%

Natural Gas 0.00005311 tCO₂e/kBtu 0.0000531 tCO₂e/kBtu ≈0%

#2 Fuel Oil 0.00007421 tCO₂e/kBtu 0.0000749 tCO₂e/kBtu -1%

The biggest…