Energy & ecology

At night speed a DC motor draws under 10 W. Over 8 hours that is less than 0.1 kWh, about 2 cents at €0.25/kWh. A whole season of cooled nights costs barely more than one euro.

For most summer days, yes: moving air lowers perceived temperature by 3 to 4°C, enough up to an actual 28-30°C. During extreme heatwaves it complements AC by allowing a higher setpoint, hence lower consumption.

A DC motor consumes far less than an equivalent AC motor, especially at low speeds where it drops to a few watts. On a device running hundreds of hours per summer, it is the first savings criterion, before diameter.

Yes, if it is reversible. In winter mode at low speed it brings warm air back down from the ceiling without creating a draught. The room becomes evenly warm and the thermostat can drop a degree, roughly 7% less heating.

In winter the blades spin opposite to summer mode: air is pulled toward the ceiling and comes back down along the walls. On a reversible model, the switch happens from the remote, at low speed.

Very little: at low speed a DC motor draws a few watts, less than an internet router. Even running through the heating hours, the cost is a few cents a day, easily offset by the recovered heat.

5 to 30 W for a DC model, 50 to 100 W for a classic AC motor. Over a full summer (8 h/day, 4 months), that is 5-19 kWh versus 48-96 kWh, roughly €2-5 versus €12-24.

Far less. A split AC draws 2,000-3,000 W versus 5-30 W for a DC fan, a ratio of 1 to 100 in power and roughly 1 to 50 in annual cost.

Yes, it is actually its most effective use. At night speed (8 W or less on premium DC models), the overnight cost is a fraction of a cent. Wind-chill lets you sleep with windows closed at under 30 dB.

Between 100 and 500 kg CO₂ equivalent per summer depending on the national grid mix, plus HFC refrigerant leaks with a GWP 1,000 to 4,000 times that of CO₂. In France (decarbonised grid), the electrical footprint is low, but refrigerant leaks remain a serious issue.

Their global warming potential is 675 to 4,000 times that of CO₂ over 100 years. The most common refrigerant (R-410A, GWP 2,088) releases the equivalent of over 600 kg of CO₂ per 300 g leak, which happens regularly at installation, servicing and end-of-life.

In most well-managed European homes (shutters, night ventilation), yes. It lowers perceived temperature by 3 to 4°C for 5 to 30 W. When AC is still needed, the fan allows raising the thermostat by 2 to 3°C, cutting AC consumption by 20 to 30%.

All techniques that keep an interior cool without mechanical energy: surface albedo, vegetation, external shading, natural stack-effect and cross-ventilation. Well combined, these levers can maintain 5 to 12°C below outdoor temperature.

Deciduous species are ideal: they shade in summer and let winter sun through (wisteria, Virginia creeper, hops). A well-covered façade sees its surface temperature drop by 10 to 15°C.

Yes, significantly. An exterior blind blocks 70 to 80% of solar flux before it crosses the glazing. An interior curtain, even thick, stops only 15 to 25%, because the heat has already entered through the glass.

The most effective combination is: shutters closed by day, night cross-ventilation, and a DC ceiling fan. Together these three gestures deliver 5 to 8°C less perceived heat for under €500 and 5 to 30 W of continuous consumption.

Yes, especially for tenants who cannot fit exterior blinds. A quality solar film (€30-60 per window, 30-minute install) reduces infrared gains by 40 to 60% with no perceptible reduction in visible light.

Rarely. Its real COP is 1.5 to 2 versus 3 to 5 for a split unit. It ejects heat back into the room if the exhaust duct is not perfectly sealed, produces 55 dB of noise, damages windows and has poor resale value. The equivalent budget in a DC ceiling fan offers a much better long-term return.