As mentioned in the above question, this depends upon the particulars of your case and for an exact answer requires a sophisticated computer simulation. To provide a guide, the following data was developed (Kavanaugh, 1992a; Kavanaugh, 1992b) for three U.S. locations with widely differing climates. The values shown are annual kWh consumption for the different system types.
| Atlanta, GA | ||||
|---|---|---|---|---|
| Cooling | Heating | DHW | Total | |
| ASHP | 3,409 | 7,396 | 4,120 | 14,925 |
| ASHP (variable speed) | 2,499 | 5,540 | 4,120 | 12,159 |
| GHP (std. eff.) | 2,599 | 4,236 | 2,620 | 9,455 |
| GHP (high eff.) | 2,079 | 3,510 | 2,509 | 8,098 |
| Spokane, WA | ||||
|---|---|---|---|---|
| Cooling | Heating | DHW | Total | |
| ASHP | 773 | 11,475 | 4,120 | 16,458 |
| ASHP (variable speed) | 435 | 9,295 | 4,120 | 13,850 |
| GHP (std. eff.) | 451 | 5,562 | 3,150 | 9,163 |
| Portland, OR | ||||
|---|---|---|---|---|
| Cooling | Heating | DHW | Total | |
| ASHP | 513 | 6,666 | 4,120 | 11,299 |
| ASHP (variable speed) | 285 | 4,706 | 4,120 | 9,111 |
| GHP (std. eff.) | 337 | 3,549 | 3,468 | 7,354 |
These figures are based on newly constructed homes conforming to local energy efficiency standards (which are much more stringent in the northwest portion of the country). GHPs are assumed to be equipped with desuperheaters for hot water heating. The balance of the water heating is by electric water heaters.
Additional savings information is available from the sources listed in section FAQ 19. The U.S. EPA report, "Space Conditioning: The Next Frontier" by L'Ecuyer and others (EPA 430-R93-004) also contains savings information.