Weatherization and Air Sealing

In the United States, buildings use one third of all energy consumed and two thirds of all electricity. Additionally, they are a major source of the pollution that causes urban air quality problems and pollutants that contribute to climate change. Buildings account for 49 percent of sulfur dioxide emissions, 25 percent of nitrous oxide emissions, and 10 percent of particulate emissions. 

Weatherization or weatherproofing is the practice of protecting a building and its interior from the elements, particularly from sunlight, precipitation, and wind, and of modifying a building to reduce energy consumption and optimize energy efficiency.

Weatherization is distinct from building insulation, although building insulation requires weatherization for proper functioning. Many types of insulation can be thought of as weatherization, because they block drafts or protect from cold winds. Whereas insulation primarily reduces conductive heat flow, weatherization primarily reduces convective heat flow.

Typical weatherization procedures include:

• Sealing bypasses (cracks, gaps, holes), especially around doors, windows, pipes that penetrate the attic ceiling, and other areas with high potential for heat loss, using caulk, foam sealant, weather-stripping, window film, door sweeps, electrical receptacle gaskets, and so on to reduce infiltration.
• Protecting pipes from corrosion and freezing.
• Installing footing drains, foundation waterproofing membranes, interior perimeter drains, sump pump, gutters, downspout extensions, downward-sloping grading, French drains, swales, and other techniques to protect a building from both surface water and ground water.
• Providing proper ventilation to unconditioned spaces to protect a building from the effects of condensation.
• Installing roofing, building wrap, siding, flashing, skylights or solar tubes and making sure they are in good condition on an existing building.
• Installing insulation in walls, floors, and ceilings, around ducts and pipes, around water heaters, and near the foundation and sill.
• Installing storm doors and storm windows.
• Replacing old drafty doors with tightly sealing, foam-core doors.
• Replacing older windows with low-energy, double-glazed windows.

The phrase "whole-house weatherization" extends the traditional definition of weatherization to include installation of modern, energy-saving heating and cooling equipment, or repair of old, inefficient equipment (furnaces, boilers, water heaters, programmable thermostats, air conditioners, and so on). The "Whole-House" approach also looks at how the house performs as a system.