Panasonic Home & Environment Co. adds two WhisperGreen-Lite models to its line of ventilation fans. Designed for 4-in. ducts, the fans feature built-in variable-speed controls and a built-in delay timer that can be set for up to 60 minutes. All models are Energy Star-rated, Home Ventilating Institute-certified and said to be ideal for complying with ASHRAE Standard 62.2. Features include: ultra-quiet operation with noise levels of less than 0.3 sones; two 18-watt compact fluorescent Energy Star-qualified light bulbs; and a nightlight feature (4-watt bulb).