Basis for Adjustment
The basis for adjustment is the documented, agreed-upon method for changing reported savings when conditions change after the measurement period. Savings are computed as a comparison, not a direct measurement: avoided energy use equals the adjusted baseline energy minus actual post-retrofit energy (plus or minus any adjustments). Because both baseline and reporting-period conditions differ, the M&V plan must state which independent variables drive energy use, how they are measured, and how the baseline is adjusted to reporting-period conditions.
Key concepts: baseline conditions (weather, occupancy, production, operating schedules), independent vs. dependent variables, static factors (which should not change, e.g., facility size, equipment count) versus dynamic factors (which legitimately vary, e.g., weather, throughput), routine vs. non-routine adjustments, and the adjustment method (formula, model, or stipulated value). Non-routine adjustments cover changes in baseline conditions such as added loads, changed occupancy, or equipment retirements.
Traps in questions: confusing a routine adjustment (weather normalization via a model) with a non-routine adjustment (a one-time baseline change); assuming savings equal metered reduction without normalization; treating a static factor as dynamic; and forgetting that adjustments must be defined before the measurement period, not invented afterward. Another trap is believing the baseline itself changes when weather varies - the baseline model is fixed and evaluated at new conditions.
Worked example: baseline model is E = 100 + 2.0 × HDD (kWh per day). Baseline period averaged 3,000 HDD and reporting period 2,500 HDD. Adjusted baseline = 100 + 2.0 × 2,500 = 5,100 kWh/day. If actual post-retrofit use is 4,400 kWh/day, savings = 700 kWh/day. If a new server load is added mid-period, that is a non-routine adjustment applied separately.