When building an energy-efficient Accessory Dwelling Unit (ADU), consider the following essential tips:
- Energy-Efficient Windows and Doors:
- Opt for windows and doors that minimize heat transfer. Proper insulation helps maintain a comfortable temperature inside the ADU while reducing energy costs1.
- LED or Energy-Efficient Lighting Fixtures:
- Use LED bulbs or other energy-efficient lighting options to reduce electricity consumption. Efficient lighting not only saves energy but also enhances the ADU’s ambiance1.
- Energy-Efficient HVAC System:
- Choose an HVAC system designed for optimal comfort and cost savings. Properly sized and efficient units can regulate temperature effectively while minimizing energy usage1.
- Water Conservation:
- Install low-flow fixtures (such as faucets and showerheads) to conserve water.
- Consider rainwater harvesting systems for irrigation or non-potable water needs2.
By incorporating these strategies, homeowners can create an ADU that is both eco-friendly and cost-effective. 
When it comes to making your Accessory Dwelling Unit (ADU) energy-efficient, consider these renewable energy options:
- Solar Panels:
- Solar panels are an excellent choice for ADUs. They can offset electricity consumption and reduce energy costs.
- In California, Title 24 requirements may mandate solar panels for ADUs, but they don’t necessarily need to be installed directly on the ADU. They can also be added to the main house or other eligible structures1.
- Heat Pump Water Heaters (HPWHs):
- For water heating, HPWHs are about three times more efficient than electric resistance or gas heaters. They significantly reduce annual energy use2.
- Geothermal Energy:
- If feasible, consider geothermal heat pumps. They utilize the earth’s natural heat to provide efficient heating and cooling.
- Wind Energy:
- If your ADU is in a windy area, small wind turbines can generate electricity.
Remember to explore local incentives and rebates for renewable energy installations specific to your area.