Energy

Energy Savings and Payback

Four tools for the energy auditor, each switched on by a checkbox. Weather normalization fits monthly bills with the ASHRAE Inverse Modeling Toolkit change-point models (2P, 3P heating, 3P cooling, 4P and 5P on the mean temperature, by the two-stage grid search of Kissock, Haberl and Claridge) or the degree-day regression at an entered base, ranks them by CV-RMSE and adjusted R² against the Guideline 14 monthly criterion, and normalizes the use to typical-year degree days. Savings applies the baseline model to the post-retrofit bills and reports the avoided energy with its fractional uncertainty at 68 % and 90 % by the Guideline 14 Annex B formula of Reddy and Claridge beside the IMT prediction-band form. Measure economics turns a list of conservation measures into first-year savings, simple payback, savings-to-investment ratio, net present value, internal rate of return, discounted payback and avoided CO2 with the escalation and discounting of NIST Handbook 135, ranked with a payback chart. Quick calculators give the lighting-retrofit energy and demand saving and the motor-replacement saving of the DOE motor tip sheet. The default bills are the classroom heat-pump example of the Bonneville Power Administration's Regression for M&V guide (12 months of kWh and heating degree days: intercept 132 kWh/day, slope 8.87 kWh/day per degree day, CV-RMSE 11.7 %), the motor case is the DOE example (75 hp, 92 to 95.5 %: 13,373 kWh/yr); the post-retrofit months and the four measures are illustrative.

2 worked examples reproduced, listed on the tool page.

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HVAC Loads · Ducts and Airflow · Psychrometrics · HVAC Equipment · Ventilation and Air Quality · Plumbing · Fire Protection · Lighting and Electrical · Controls and Commissioning · Codes and Compliance