California Is Investing Billions in Clean Energy But Many Homes Lose Up to 30% of It Before It’s Used

Building-science data highlight duct leakage as a widespread, overlooked issue undermining energy savings in 95% of San Jose homes, according to local experts.

SAN JOSE, CA, UNITED STATES, January 15, 2026 /EINPresswire.com/ -- As California accelerates investments in clean energy, home electrification, and residential efficiency programs, building-science data indicate that many homes are quietly losing as much as 25–40% of heated and cooled air through leaks in unsealed ductwork before it ever reaches living spaces. According to San Jose-based home performance company MaxSeal, the issue is widespread in older housing stock across Silicon Valley, where duct systems were installed decades ago and rarely tested or sealed to modern efficiency standards.

Federal agencies including the U.S. Department of Energy and ENERGY STAR have long identified duct leakage as one of the largest sources of residential energy waste. In homes with forced-air heating and cooling, researchers estimate that air loss through ducts can rival and, in some cases, exceed the impact of inefficient appliances or outdated windows. Despite this, duct systems remain one of the least inspected components of a home’s energy infrastructure.
The findings highlight a growing contradiction in residential energy upgrades. While many homeowners are replacing HVAC equipment, installing heat pumps, or pursuing electrification incentives, building-performance experts note that efficiency gains can be significantly reduced if air distribution systems are leaking behind walls, in attics, or beneath floors.

“In many homes, the equipment is not the primary issue,” MaxSeal representatives say. “If conditioned air is escaping before it reaches the room, even high-efficiency systems cannot perform as intended.”

The issue is particularly pronounced in San Jose and surrounding communities, where much of the housing stock predates current energy codes. Many homes were originally built without central heating or air conditioning and later retrofitted with ductwork, often before leakage testing requirements existed. As a result, hidden gaps and leaky joints can persist for decades without detection.

Modern diagnostic testing now allows contractors to measure duct leakage directly and verify improvements after repairs are made. Non-invasive sealing methods, including the patented Aeroseal duct sealing process, make it possible to address leaks throughout an entire duct system, including sections concealed behind finished walls, without major demolition, providing documented performance results rather than estimates.

The issue is gaining renewed attention as California households contend with rising electricity and natural gas rates and as state and federal programs increasingly emphasize efficiency improvements in existing homes. Recent incentive programs have highlighted air sealing and duct improvements as among the most cost-effective ways to reduce residential energy demand while improving indoor comfort and air quality.

For homeowners, the takeaway is not necessarily that a major system replacement is required, but that meaningful gains in efficiency, comfort, and indoor environmental quality can be achieved by addressing their long-overlooked existing ducts.

About MaxSeal
MaxSeal is a San Jose–based home performance company specializing in residential duct sealing and air-distribution efficiency. The company uses diagnostic testing and non-invasive repair methods, including the patented Aeroseal technology, to help reduce energy loss in existing homes.
For more information, visit https://maxseals.com

Wendy Ames
MaxSeal
+1 408-400-3630
email us here
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