How do inefficient water heaters and furnaces increase the use of fossil fuels?

Inefficient water heaters and furnaces consume more energy to maintain desired temperatures, leading to increased fuel consumption. As they work harder, they burn more fossil fuels, such as natural gas or oil, to produce heat, thereby raising greenhouse gas emissions. This not only contributes to environmental degradation but also exacerbates energy costs for consumers. Overall, inefficient appliances lead to higher reliance on fossil fuels, undermining efforts to transition to cleaner energy sources.