Heating and air conditioning can take up as much as 43% of your power bill. There are some useful tricks though that can allow you to save some cash. 1. Most heat that accumulates inside a house comes directly from the sun shining onto the roof or through windows, and heating the house directly. Planting leafy trees around the building’s exterior will stop the sun from reaching inside your home. If the trees or shrubs shade your air conditioner, you could boost your AC’s efficiency by up to 10 percent, according to the U.S. Department of Energy. 2. Solar screens, or mesh-like window screens, intercept up to 70 percent of solar energy before it gets into the house. Window screens are particularly effective on east- and west-facing windows. Window films are another option. They are transparent, metalized sheets that reflect heat before it can be transmitted through glass. However, windows must be shut for window films to work, while solar screens do double-duty, keeping sun and insects out even with windows open. 3. Lower your air conditioner’s thermostat setting to 78 degrees Fahrenheit when you’re at home. But let that number rise to a warmer temperature at night or when you’re away from home. You can save 5 percent to 15 percent on your air-conditioning bills by raising the temperature setting on your thermostat when you’re away and don’t need cooling. 4. AC efficiency is mostly a function of the technology. Keep the filter clean to allow for good air movement and keep the unit level so the condensation drains properly.If you replace your older room air conditioner with a newer unit, you could cut your energy costs in half. Look for a high-energy-efficiency ratio, or EER, or an Energy Star-qualified unit. Higher EER ratings mean a more efficient air conditioner. Energy Star refers to a system adopted by the U.S. Environmental Protection Agency and Department of Energy to identify energy-efficient products.