What can a technician recommend to improve energy efficiency after a home energy audit?

Improving insulation and sealing air leaks is a highly effective recommendation for enhancing energy efficiency in a home after an energy audit. Insulation plays a crucial role in maintaining temperature stability inside a house, reducing the need for heating and cooling systems to work harder. When insulation is inadequate, or when there are significant air leaks, conditioned air can easily escape during the summer and winter months, resulting in increased energy consumption and higher utility bills.

By addressing these issues, homeowners can create a more comfortable living environment while also reducing energy use and greenhouse gas emissions. Effective sealing of leaks can include caulking around windows and doors, adding weatherstripping, and sealing any gaps in the building envelope, which collectively help in maintaining consistent indoor temperatures without excessive reliance on HVAC systems.

In contrast, the other choices would not have the same positive impact on energy efficiency. More windows could potentially increase heating and cooling demands due to added surface area for heat loss or gain, while single-pane windows offer poor insulation compared to double or triple-pane alternatives. Increasing duct size may improve airflow but does not directly address energy consumption inefficiencies related to insulation or air sealing. Thus, focusing on insulation and air sealing is the most effective strategy for improving a home's energy efficiency.