Variable speed fans operate on a simple principle: they are able to spin at different speeds depending on the heating and cooling needs of your home. Usually, they operate at lower speeds, delivering a steady, reliable stream of warm or cool air to your home. This helps control humidity levels, utility costs and system noise. When conditions become more extreme, the fan speed increases so that the system can meet increased demand, guaranteeing that on even the hottest days or coldest nights, you're comfort needs will be met.