; and (H) advanced renewable energy manufacturing techniques. (2) Mechanical, chemical, and thermal energy storage technologies, which include— (A) advanced grid-scale energy storage technologies with storage durations in the range of 10 to 50 hours; and (B) grid-scale energy storage projects that can economically balance electricity supply and demand across seasons. (3) Electricity transmission technologies, which include underground high-voltage direct current electricity transmission. (4) Commercial, industrial, and residential energy efficiency technologies, which include— (A) retrofit packages that reduce the energy used by an average single-family home by at least 50 percent at a cost of no more than $25,000 per such home; (B) smart heating, ventilation, and air conditioning control technologies that— (i) can be used in commercial buildings that have between 5,000 and 30,000 square feet of floor area; (ii) can reduce heating, ventilation, and air conditioning energy consumption by an average of at least 20 percent compared to average commercial buildings; (iii) yield energy cost savings that can provide at least a 50-percent annual return on the original investment; and (iv) may include a cloud-based information technology; (C) those technologies that the Secretary identifies as having the ability to improve energy efficiency or reduce emissions in heavy industries, which include those that produce or refine aluminum, steel, cement, oil, or fertilizer; and (D) flexible load technology improvements to reduce peak demand. (5) Industrial process and building electrification technologies, which include— (A) heat pump space heaters; (B) heat pump water heaters; (C) induction stoves