If Local Law 84 measures how much energy a building uses, Local Law 87 asks why — and what to do about it. It requires large NYC buildings to commission a professional energy audit and a retro-commissioning study once a decade, and to file the results with the City. Done well, it is a roadmap for cutting energy, cost and Local Law 97 carbon. This article is part of our NYC compliance series.
Who's covered and how often
LL87 applies to buildings over 50,000 square feet — a higher threshold than LL84. Each covered building must complete the requirements every 10 years, on a staggered schedule tied to the last digit of its tax block number, and file an Energy Efficiency Report (EER) with the Department of Buildings by December 31 of its due year.
The two halves: audit + retro-commissioning
- Energy audit — an ASHRAE Level 2 survey of the building's energy systems by a qualified professional, identifying efficiency measures along with their estimated savings and costs.
- Retro-commissioning (RCx) — a systematic tune-up of existing equipment and controls so they perform as intended: correcting schedules, setpoints, sensors, dampers and the like. RCx targets the "free" or low-cost fixes that restore performance buildings have quietly lost over time.
The penalties
Failing to file the EER by the deadline is a Class 2 violation: roughly $3,000 for the first year and $5,000 for each subsequent year until you comply. As with the other laws, the deeper cost is the lost opportunity — the audit and RCx usually pay for themselves through the savings they uncover.
The LL97 connection
LL87 and Local Law 97 are natural partners. The audit surfaces a menu of measures; the question LL97 forces is which of them actually reduce carbon enough to stay under your limit. That is where energy modeling comes in — taking the audit's measure list and quantifying each one's impact on emissions and penalties, so capital goes to the upgrades that matter most. Retro-commissioning, meanwhile, often delivers the cheapest carbon reductions available, making it a logical first move toward LL97 compliance.
What owners should do
Know your building's LL87 due year, engage qualified professionals well ahead of the December 31 deadline, and — crucially — treat the audit as a planning tool, not paperwork. Pair it with an energy model and a Local Law 97 projection so the measures you implement do double duty: satisfying LL87 and cutting your carbon trajectory.
Turning an LL87 audit into an LL97 plan?
We model the measures an LL87 audit surfaces against your Local Law 97 limits — so you fund the upgrades that cut the most carbon per dollar. Let's talk.
Get in touchThis article is general guidance and reflects information available at the time of writing. NYC requirements, thresholds, deadlines and fines are set by the City of New York and may change — always confirm current rules with the NYC Department of Buildings for your specific building.