Air Change Rate (ACH) Calculator
Calculate the air changes per hour (ACH) for a room or building. Determine ventilation rate from airflow volume and room size.
Free Efficiency Calculators
11 toolsThermostat, ventilation, degree day, and energy efficiency calculators. Browse our free efficiency tools below — no sign-up required.
Cool Roof Savings Calculator
Calculate cooling energy savings from a cool roof (reflective roofing). Estimate reduced air conditioning costs and payback from high-reflectance roofing materials.
Cooling Degree Days (CDD) Calculator
Calculate cooling degree days from daily temperatures. Estimate CDD for energy analysis, air conditioning cost planning, and cooling season comparisons.
ERV/HRV Savings Calculator
Calculate energy savings from an ERV or HRV ventilation system. Compare heat recovery ventilation costs to standard exhaust-only ventilation.
Green Roof Savings Calculator
Calculate energy savings and benefits from installing a green (vegetated) roof. Estimate insulation value, cooling savings, and stormwater management benefits.
Heat Loss & Degree Day Calculator
Calculate home heat loss using heating degree days. Estimate seasonal heating energy consumption and costs based on HDD and building thermal performance.
Heating Degree Days (HDD) Calculator
Calculate heating degree days from daily temperatures. Estimate HDD for energy analysis, fuel planning, and heating season comparisons.
Programmable Thermostat Savings Calculator
Calculate energy savings from using a programmable thermostat with temperature setbacks. Estimate cost reduction from scheduled heating and cooling adjustments.
Setback Temperature Savings Calculator
Calculate how much you save by lowering your thermostat a specific number of degrees. Estimate savings per degree of temperature setback.
Smart Thermostat Savings Calculator
Calculate annual savings from installing a smart thermostat. Estimate energy reduction from automatic scheduling, learning, and occupancy detection.
Ventilation CFM Calculator
Calculate the required CFM ventilation rate for a room or building. Determine airflow needs based on room size, occupancy, and ASHRAE standards.