Which building element has the greatest impact on a home's energy efficiency?

The building envelope has the greatest impact on a home's energy efficiency because it acts as the barrier between the interior and exterior environments. This includes the walls, roof, windows, doors, and foundation. A well-designed and properly constructed building envelope minimizes heat loss in the winter and heat gain in the summer, resulting in reduced energy consumption for heating and cooling.

Effective insulation, air sealing, and moisture control within the building envelope contribute significantly to energy performance. These factors help to maintain comfortable indoor temperatures while lowering the demand on heating and cooling systems. A compromised building envelope, characterized by gaps, inadequate insulation, and poor sealing, can lead to increased energy costs and reduced comfort, making its integrity critical to overall efficiency.

While other elements like the roof structure, efficiency of the heating system, and quality of windows and doors are also important, they do not offer the same comprehensive control over energy loss and gains as the building envelope itself. Each of these factors can influence energy performance, but improving the building envelope typically provides the most significant long-term benefits to a home's overall energy efficiency.