Hydrogen integration in buildings: investigating leakage from common gas connections

Hydrogen has the potential to be a critical component for decarbonizing the built environment, yet its integration poses unique challenges, particularly regarding leakage from gas distribution systems. This paper reports results from an experimental study on the leakage of hydrogen from 30% by volume blends in methane through fittings used in building gas networks. Static leakage tests were performed, monitoring pressure decay from simulated sections of indoor distribution systems assembled with common gas connections, repeated over multiple days and under different configurations to gather a statistically significant sample size. Gas composition was analyzed near the end of tests to determine any preferential leakage of hydrogen over methane. Results show that correctly assembled fittings exhibit minimal or no leakage for natural gas and hydrogen blends at typical indoor pressures. Exceptions in the present work were corrugated stainless steel compression fittings and worn tapered pipe thread fittings, with average leak rates of 4.6 × 10−5 and 3.4 × 10−5mol·m-³·min−1 per fitting, respectively. Hydrogen blends exhibited leak rates comparable to pure methane, and the H2:CH4 ratio remained at the initial 3:7 value, indicating no preferential leakage. Leak rates were also converted to energy units for comparison from an energy efficiency perspective.