Insulation/ CALCULATOR
Estimate daily and period electricity use from the measured or rated supply and extract fan power.
FROM ESTIMATE TO ACTION
Use electrical input in W for supply and extract fans at the same operating setting, not airflow, motor output or a control percentage. If a documented value already combines both fans, count it once in one power field and enter zero in the other; record that choice. Do not add component powers to the same combined reading. Separate any controls or heaters included by the meter from a fan-only estimate.
35 + 35 = 70 W at 24 h/day gives 1.68 kWh/day and 613.2 kWh over 365 days, assuming unchanged operation. These are example inputs, not typical consumption. For changing modes, calculate each mode separately and add its energy: 70 W × 8 h + 140 W × 2 h = 0.84 kWh for that day. A fan-speed percentage is not automatically the same percentage of electrical power.
At an entered price of 0.20 per kWh, 613.2 kWh costs 122.64 in that currency. Zero price makes calculated cost zero, not electricity use. Record the tariff basis and account for standing charges or time-dependent prices separately. Standby, controls and heaters may need separate measurement. This electricity total does not establish airflow, recovered heat, safe ventilation or the benefit of shortening operation.