90.1-2010 Section 11 - Interpretation for Zonal WSHP
Hi all - I'm hoping to solicit a few opinions on an interpretation of Section 11 rules for 90.1-2010.
I'm modelling a mid-sized office in Canada that uses zonal water-source heat pumps. The water loop is heated to around 60-70 degF by gas boilers, and is cooled by a water-cooled tower to around 90 degF.
What should the baseline system be per Section 11 (ECB) rules? On one hand I would suggest System Type 6, as heat is provided to the space via heat pump and it gives me a straightforward comparison between WSHP in the Proposed and Reference, with towers used for loop heat rejection in both cases (per note g of Table 11.3.2).
The alternative would be System 7. If I consider the building to be a control volume, heat pumps are not the primary energy source working to bring heat into the control volume; rather, the primary heating energy entering is the gas used in the boilers... With System Type 7 I would be comparing my Proposed WSHP+Boiler+Tower to the Reference FPFC+Chiller+Boiler.
Does anybody have any opinions they could share, official or unofficial as they might be?
EDIT: Minor additions to address Daniel's reply
Comments
Assuming the cooling tower is water cooled?
Note g on Table 11.3.2A states that water source heat pumps will be connected to a common water loop with heat rejection by an axial fan closed-circuit evaporative cooler. So I don't think the DX cooling means that the condenser on the individual heat pump is air cooled.