Which method listed provides the greatest savings per year?

Draught-proofing involves sealing cracks and gaps around doors, windows, and other areas of a building to reduce unwanted air leaks. This method can lead to significant energy savings as it minimizes the amount of heated or cooled air that escapes, thereby reducing the energy needed to maintain a comfortable indoor temperature. Improved energy efficiency directly correlates with lower energy bills, resulting in considerable savings over the course of a year.

In contrast, while loft insulation and other options also contribute to energy savings, they typically involve higher initial costs and their savings can be gradual rather than immediately noticeable. Loft insulation is effective for retaining heat but may not offer as rapid a return on investment as draught-proofing. Temperature controls can enhance efficiency by allowing residents to adjust the thermostat according to their needs, but savings will vary widely based on individual usage patterns. The hot water tank can be optimized for energy efficiency, but this typically pertains to maintaining existing systems rather than making impactful changes that lead to vast savings.

Overall, draught-proofing is often regarded as one of the most cost-effective energy efficiency measures due to its relatively low installation cost and its immediate impact on energy bills.