ECB / CH11 Heat Pump Chiller

asked 2023-05-17 06:38:32 -0500

Have a project pursuing Performance Compliance via Chapter/Section 11 compliance. The central plant has water cooled chillers and a Heat Pump Chiller and Gas Boilers. A point of clarity is that the Heat Pump Chiller is controlled to generate heating first and 'recover' free cooling. This is different than a Chiller with heat recovery, as that is could controlled to the chilled water temperate and any free heat is 'recovered'.

The HVAC Systems map and descriptions have me scratching my head a bit. Water cooled chiller - easy. But for the heating source, it's a blend of Heat Pump and Fossil Fuel. There are additional tables that provide guidance when you have a mix of fuel sources for the chiller - but there is not a similar table to heating sources.

My current thinking is that this falls back to Section 11.5.2 (j) dealing with '...mixed fuel heating sources, the system or systems that use the secondary heating sources type (the one with the smallest total installed output capacity for the the spaces served by the system) shall be modeled identically in the budget building design, and the primary heating source type shall be used in Figure 11.5.2..."

As my fossil fuel boilers are far larger this sets the Baseline with Fossil Fuel Boilers - but the Baseline also gets the HP Chiller (yes?). If the design team selects a more/high efficiency HP Chiller option, can they still get credit for this (due to the 'modeled identically' part of 11.5.2 (j))? Seems unfair (and a bit odd) if they didn't get credit for this.

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