It is the first time wind has been included alongside nuclear, thermal, hydro, geothermal, solar and purchased energy. It suggests wind will be treated on an equal footing with other sources of energy in the future.
The sub-committee is part of the Ministry of Economy Trade and Industry (METI), which exerts a powerful influence over energy usage in Japan.
In Japan, wind continues to operate at a disadvantage to solar power, which claims higher feed-in tariffs and is exempt from environmental assessment regulations.
"The general feeling was that windpower could no longer be excluded based merely on the fact that it is unstable," a METI spokesman said. "Use of wind power is on the rise, and it was felt that it was time to include it as a safe form of energy."
Committee member Toshihiro Matsumura, a professor in the Institute of Social Science at The University of Tokyo was cited as the main driver behind the inclusion of wind in peak electricity demand calculations.
While the initial decision relates only to the period from December to March, wind is seen likely to be included in similar calculations that cover the peak demand months of summer.