Rooms in your home that have western exposure (walls and windows) will be warmer in the afternoon than other places due to solar gain from the sun through windows and walls. Window coverings must be drawn on in the afternoon on any west-facing windows to avoid these increased indoor temperatures. Your air conditioning system cannot adjust airflow throughout the day based on the movement of the sun. If you fail to draw window coverings, your rooms will get hot, and your energy usage will rise. It is also a good idea to install awnings over west-facing windows if possible or plant trees to shade these windows in the afternoon.