| Performance Classification | Comments |
| Good | Low energy consumption indicative of careful control and good energy management procedures |
| Satisfactory | Energy usage consistent with sensible operating procedures |
| Fair | Barely average performance for typical situation, significant saving should be achievable |
| Poor | Energy usage is high for typical situation indicative of significant heat losses in winter and/or poor control of energy use |
| Very Poor | Energy usage is excessive, immediate action should be taken to investigate and remedy. |