NYC Heat Sensor and Underlying Conditions Program Buildings

HPD runs two programs for buildings with repeat problems: the Heat Sensor Program, for buildings that keep failing to provide heat, and the Underlying Conditions Program, for buildings with widespread mold and water leaks. The city's open data lists 200 Heat Sensor selections covering 8,569 apartments, and 700 Underlying Conditions orders since 2013, of which 567 (81%) have been discharged.

What the two programs are

Heat Sensor Program

Local Law 18 of 2020, as amended by Local Law 70 of 2023, requires HPD to pick 50 class A multiple dwellings that consistently fail to provide adequate heat. HPD says it selects them mainly by the number of heat violations issued over the previous two years and whether heat complaints came from more than one apartment. The original rule called for a new group every two years; under the 2023 amendment, HPD must select 50 buildings every year starting July 1, 2024.

Owners must install an internet-connected temperature sensor in one living room of each apartment, chosen by the tenant (tenants can refuse), by October 1 and send HPD the readings for each month of the heat season. HPD inspects the buildings at least twice a month from October 1 through January 31. Buildings stay in the program for four years unless discharged early, which requires no heat violations in the previous heat season plus installed sensors, kept records and a valid HPD registration. See NYC heat rules for the temperatures the law requires.

Underlying Conditions Program

Under Local Law 6 of 2013, HPD issues an order requiring an owner to find and fix the underlying cause of mold or leaks that affect many apartments, instead of patching each one. A building qualifies when enough of its units have an uncorrected Class B or C mold or leak violation from the past year: half of units in 3–5 unit buildings, a quarter in 6–9 unit buildings and 15% in buildings with 10 or more. HPD says it picks roughly 50 to 100 buildings a year, prioritizing conditions linked to asthma.

The owner has four months to correct the conditions (a two-month extension is possible with an engineer's or architect's affidavit). To get the order rescinded, an engineer or architect must certify the repair and HPD inspectors must find at least 80% of the violations corrected. Owners who don't comply face a civil penalty of $1,000 per apartment, with a $5,000 minimum, and HPD can do the work and bill them. Tenants can read more in mold rights for NYC tenants.

Buildings added each year

The Heat Sensor file has four cohorts of exactly 50 buildings: July 1, 2020, July 1, 2022, July 1, 2024 and June 11, 2025. The newer cohorts are bigger buildings: the 2020 group holds 1,549 apartments, while the 2024 group holds 2,471.

Underlying Conditions orders ran between 26 and 83 a year from 2013 through 2019, mostly issued each fall. The file shows no orders in 2020 or 2021. Orders resumed in December 2022, and 2025 was the biggest year on record, with 124 orders covering 4,590 apartments.

How many got out

Most older Underlying Conditions orders have been discharged. Of the 443 orders issued from 2013 through 2019, 20 are still active. Recent orders are a different story: 26 of 65 orders from 2024 and 71 of 124 from 2025 remain active. The latest order in the file is dated September 26, 2025, so even with the two-month extension every 2025 order is past its correction deadline. An order stays active until HPD rescinds it, which requires the owner to file paperwork and inspectors to confirm repairs.

39 of the Underlying Conditions orders went to buildings that had already had one, so the 700 orders cover 661 different buildings.

For the Heat Sensor Program, the open data cannot answer the question. Every one of the 200 rows is marked Active and none has a discharge date, including the July 2020 group that HPD's rules say should have finished its four-year term. Treat the HSP status column as unreliable.

Where the buildings are

The Bronx has the most buildings in both programs: 83 of the 200 Heat Sensor selections (42%) and 264 Underlying Conditions orders. Bronx Heat Sensor buildings are large, averaging 52 apartments each, compared with 27 in Brooklyn. Staten Island has 2 Heat Sensor buildings and 6 Underlying Conditions orders, none still active.

By neighborhood (NYC Planning's Neighborhood Tabulation Areas), Harlem (North) and Crown Heights (North) have the most Underlying Conditions orders (28 and 26). For the Heat Sensor Program, Harlem (South) and Crown Heights (North) each have 8 buildings.

Limits of this data

• The Heat Sensor file looks out of date. It was last updated on 2026-08-01. HPD's program page lists a July 2026 building list, but no 2026 cohort appears in the open data, and no building is shown as discharged.
• Unit counts are current. HPD notes that total units reflect its records when the file was run and may differ from the count at selection.
• Discharged does not mean fixed everywhere. An Underlying Conditions order can be rescinded once 80% of the violations are corrected.
• Selection is not a full list of bad buildings. Each program picks a limited number of buildings by set criteria. For the Underlying Conditions Program, HPD can also skip one- and two-family homes and buildings already under other enforcement, such as the Alternative Enforcement Program.