(a)  Nonresidential Occupancies. Service water heating systems in nonresidential buildings shall meet the requirements of 1, 2 below, or meet the performance compliance requirements of Section 140.1:

1. School buildings less than 25,000 square feet and less than 4 stories in climate zones 2 through 15. A heat pump water heating system that meets the applicable requirements of Sections 110.1, 110.3 and 120.3.

2. All other occupancies. A service water heating system that meets the applicable requirements of Sections 110.1, 110.3, 120.3, and 140.5(c)

EXCEPTION to Section 140.5(a)1: Water heating system serving an individual bathroom space may be an instantaneous electric water heater. 

(b)  Hotel/Motel Occupancies. A service water heating system installed in a hotel/motel building shall meet the requirements of Section 170.2(d).

(c)   High capacity service water heating systems. Gas service water-heating systems with a total installed gas water-heating input capacity of 1 MMBtu/h or greater shall have gas service water-heating equipment with a minimum thermal efficiency of 90 percent. Multiple units can meet this requirement if the water-heating input provided by equipment with thermal efficiencies above and below 90 percent averages out to an input capacity-weighted average of at least 90 percent.

Exception 1 to Section 140.5(c): If 25 percent of the annual service water-heating requirement is provided by site-solar energy or site-recovered energy.

Exception 2 to Section  140.5(c): Water heaters installed in individual dwelling units.

Exception 3 to Section  140.5(c): Individual gas water heaters with input capacity at or below 100,000 Btu/h shall not be included in the calculations of the total system input or total system efficiency.

NOTE: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code. Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.8, and 25943, Public Resources Code.