Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Consider @StefanG comment here.
The system is tasked with conditioning the building. The air-cooled HP absorbs and rejects heat to the ambient. The cost of this is the energy consumed by the condenser fan. The water-cooled HP absorbs and rejects heat to a water loop. Maintaining the water loop at reasonable temperatures comes at a cost (boiler - 766423 kBtu, tower fans - 137367 kBtu, and water pumps - 66130 kBtu).
Differences in efficiency for heating and cooling would depend upon the outdoor unit (condenser in cooling mode, evaporator in heating mode) temperatures.
In cooling mode, the air-cooled HP rejects heat to ambient where the condensing temperature is the outdoor air temp. The water-cooled HP rejects heat to a water loop at the water temperature. When the water temperature is less than the outdoor air temperature, the water-cooled HP should operate more efficiently, but at a cost of water pumping and cooling tower fan energy.
Similar for heating where a higher water temperature compared to outdoor would provide better efficiency, however, the water temperature should nearly always be higher than winter outdoor temps and you should see an air-side heating energy savings (which I don't see here) which would be offset (or exceeded) by the boiler.
From this point, I would investigate the air-side Heating/Cooling Electricity use to see if those numbers make sense. You can see what meters are being summed to provide the Heating Electricity Use and Cooling Electricity Use by looking at the mtd file.
| | 2 | No.2 Revision |
Consider @StefanG comment here.
The system is tasked with conditioning the building. The air-cooled HP absorbs and rejects heat to the ambient. The cost of this is the energy consumed by the condenser fan. The water-cooled HP absorbs and rejects heat to a water loop. Maintaining the water loop at reasonable temperatures comes at a cost (boiler - 766423 kBtu, tower fans - 137367 kBtu, and water pumps - 66130 kBtu).
Differences in efficiency for heating and cooling would depend upon the outdoor unit (condenser in cooling mode, evaporator in heating mode) temperatures.
In cooling mode, the air-cooled HP rejects heat to ambient where the condensing temperature is the outdoor air temp. The water-cooled HP rejects heat to a water loop at the water temperature. When the water temperature is less than the outdoor air temperature, the water-cooled HP should operate more efficiently, but at a cost of water pumping and cooling tower fan energy.
Similar for heating where a higher water temperature compared to outdoor would provide better efficiency, however, the water temperature should nearly always be higher than winter outdoor temps and you should see an air-side heating energy savings (which I don't see here) which would be offset (or exceeded) by the boiler.boiler and water pump energy.
From this point, I would investigate the air-side Heating/Cooling Electricity use to see if those numbers make sense. You can see what meters are being summed to provide the Heating Electricity Use and Cooling Electricity Use by looking at the mtd file.
