There are a number of cost-effective upgrades that can make a house more energy efficient. Here are a few ideas:

1. Install a programmable thermostat: A programmable thermostat allows you to set the temperature of your home to match your schedule, so you don't waste energy heating or cooling an empty house.
2. Seal air leaks: Air leaks can account for a significant portion of a home's energy loss. Sealing these leaks with weatherstripping or caulk can help reduce drafts and keep your home more comfortable.
3. Upgrade to energy-efficient appliances: Appliances like refrigerators, washing machines, and dishwashers are major energy users. Upgrading to Energy Star certified models can save you money on your energy bills and reduce your carbon footprint.
4. Add insulation: Insulating your attic, walls, and basement can help keep your home warm in the winter and cool in the summer. This can save you money on heating and cooling costs and make your home more comfortable.
5. Use low-flow showerheads: Low-flow showerheads use less water than traditional showerheads, which can save you money on your water bills and reduce your energy use.
6. Install solar panels: Solar panels can help you generate your own electricity and save money on your energy bills. While the upfront cost can be high, many states offer incentives and tax credits to help offset the cost.