Building Half-Life

Abstract

Joining the NYC Department of City Planning's MapPLUTO dataset with 37 years of Department of Buildings demolition filings, we construct a survival analysis of every building currently standing in New York. Each structure's life is measured as the years from its recorded year of construction to either a confirmed demolition event or the observation horizon (2026).

The demolition subset is DM-filtered from DOB Job Application Filings. The dataset reliably covers 2000 onward; earlier filings exist sporadically and are treated as right-censored. The 9,461 figure reflects the 2000–2025 DM-coded window joined to PLUTO on BBL.

The result is the first Kaplan-Meier survival curve for NYC's building stock, stratified by era. For every era cohort — pre-1900, 1900–1940, 1940–1970, 1970–2000, post-2000 — the median lifetime exceeds the observation window. Half of every generation of New York buildings is still alive, and we have not yet lost most of what was built.

This finding has consequences. The construction industry designs new commercial buildings to an assumed 50-year service life. The 1970–2000 cohort's 0.21% demolition rate implies that at current demolition hazards, median lifetime exceeds the observation window by decades — not the 50-year service life convention in ASHRAE/RSMeans. Every demolition decision that invokes “end of service life” against a building younger than 100 years is being made against a standard the city's own empirical record does not support.

Cohort detail

“Not reached” means more than half of that cohort is still standing at the 2026 observation horizon. A median lifetime cannot be estimated above the observation window.

What this means

1. The industry design life is a fiction.

U.S. commercial buildings are designed to an assumed 50-year service life (per ASHRAE and RSMeans cost conventions). Against the NYC record, that assumption is not conservative — observed median lifetimes in every cohort exceed the 37-year observation window, and the 1970–2000 cohort's 0.21% demolition rate implies a median far beyond 50 years. When embodied-carbon policy treats a 50-year-old building as meeting its design life, it is applying a standard the data does not support.

2. Demolition is an anomaly, not an end stage.

Of 818,108 structures we analyze, only 1.16% have been demolished in nearly four decades of records. Demolition is a rare event in New York's built environment. A framework that accounts for buildings as if they inevitably reach a scheduled end — the “whole-of-life” energy accounting convention — is measuring against a life stage most buildings never reach.

3. Embodied carbon is a durability problem.

When a building that could have lived to 150 years is demolished at 50, the consequence is not only the operational carbon saved by what replaces it — it is the entire embodied footprint of the replacement, imposed on top of a structure that still had a century of service remaining. The 172 million square feet of floor area demolished in our dataset represents approximately 10.8 megatonnes of embodied CO₂e — nearly all of it avoidable if we had built to durability rather than to pro-forma.

4. Preservation is not a subsidy. It is the baseline.

The survival curves do not flatter preservation as a policy preference; they reveal it as the default behavior of the city's building stock. New York did not become a city of old buildings through deliberate policy choices. It became a city of old buildings because its buildings do not die on schedule.