This book contains peer-reviewed papers presented at the 12th International Conference on Energy Efficiency in Domestic Appliances and Lighting (EEDAL'24), held in Kitakyushu City, Japan from 7-9 October 2024. Energy efficiency helps to mitigate CO2 emissions and at the same time increases the security of energy supply. Energy efficiency is recognized as the cleanest, quickest and cheapest energy source. Not only this, but energy efficiency brings several additional benefits for society and end-users, such as lower energy costs, reduced local pollution, better outdoor and indoor air quality, etc. However, in some sectors, such as the residential sector, barriers to investments in energy efficiency remain. Legislation adopted in several jurisdictions (EU, Japan, USA, China, India, Australia, Brazil, etc.) helps in removing barriers and fosters investments in energy efficiency. These initiatives complement innovative financing schemes for energy efficiency, the provision of energy services by energy service companies and different types of information programs. At the same time, progress in appliance technologies and in solid state lighting offer high levels of efficiency. LED lighting is an example. As with previous conferences in this series, EEDAL'24 provided a unique forum to discuss and debate the latest developments in energy and environmental impact of households, including appliances, lighting, heating and cooling equipment, electronics, smart meters, consumer behavior, new technology developments, policies, and programs. In addition, EEDAL also addressed non-technical issues such as consumer behavior, energy access in developing countries, and demand response.