Build Tight

Leaky homes use more energy to heat and cool them. Occupant comfort can also be a problem in drafty homes. Conversely, homes that are "built tight" may need mechanical ventilation to maintain good indoor air quality.

To improve residential energy efficiency and indoor environmental quality, it's important to understand the current air leakage characteristics of U.S. and California homes and the factors that are associated with excess air leakage.

To characterize the U.S. housing stock, researchers analyzed air leakage data of 134,000 single-family detached homes, including 4,500 homes in California. An air leakage database, called the Residential Diagnostics Database (ResDB), was compiled. ResDB contains blower door measurements and other diagnostic test results, such as duct leakage measurements of U.S. homes.

Multizone Leakage Methods Analysis

Inter-zone leakage (for instance, chemical transport from an attached garage into a house) can have a negative impact on indoor air quality. Inter-zone leakage testing methods can also be used for energy-efficiency objectives to identify leakage pathways in homes.

While a number of strategies have been used to determine inter-zone leakage, currently no standard exists for this measurement. As part of the RESAVE project, accurate methods were identified to quantify the inter-zone leakage using fan-pressurization testing.

Energy Benefits of Air Sealing

Building tight reduces infiltration and associated energy costs, yet often creates a need for mechanical ventilation to supply acceptable indoor air quality. Ventilation is required to remove indoor-generated pollutants and excess moisture, and to provide a sufficient supply of outdoor air to ensure acceptable indoor air quality.

As part of the RESAVE program, an Incremental Ventilation Energy (IVE) model was developed to enable analysis of air sealing and ventilation impacts for many different types of homes. The IVE model was built to accommodate variations across climate; baseline air-tightness and other building structural characteristics; the performance characteristics of existing or replacement HVAC equipment; and occupant-influenced equipment operational schedules and settings.

The IVE model provides robust estimates of the benefits of increasing residential envelope air tightness and the costs and indoor air quality benefits of various ventilation system approaches and technologies. The model also highlights the uncertainties associated with unknown or poorly understood parameters.