Should I open the windows?

Compares indoor and outdoor air by total heat content (temperature and moisture), then prices the difference with your own equipment.

Inside

°F
%

Outside

°F
%
Weather apps usually report dew point; enter whichever you have.
Equipment, house, and pricing
Yellow EnergyGuide sticker or model-number lookup. Old units 10–12, recent 14–16. More
Spec sheet or ENERGY STAR label. Typical 1.3–2.0. From pints/day and watts: pints × 0.473 ÷ (W × 0.024). Lookup
Total bill ÷ kWh used on the bill.
Sets barometric pressure. Small effect.
Floor area × ceiling height, for the space you are ventilating.
Estimate: cracked 0.5–1, open 1–3, cross-breeze 3–6, fan CFM×60÷ft³.
Scales the dollar figures.
Sensor slop. 1.5 ≈ a ±4% RH sensor error.

Where this outdoor air sits

Windows winWindows loseMarginal / trade-offNot physically possible (dew point above temperature)

Air properties

InsideOutsideOutside − inside

Energy for this session

Method: saturation vapor pressure from the Buck (1981) equation; humidity ratio W = 0.62198·Pw/(P−Pw); moist-air enthalpy h = 1.006·T + W·(2501 + 1.86·T) kJ/kg; latent heat ≈ 2465 kJ/kg. In AC mode, the total load through the coil is m·Δh and electricity is load ÷ COP. In dehumidifier mode, imported moisture costs (liters ÷ IEF) kWh, and all of that electricity plus the latent heat of the condensed water is released into the room as heat. Everything here is a steady-state estimate that ignores thermal mass, fan energy, and infiltration you'd have anyway.