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Air Sealing and Insulating Walls to Reduce Heat Gain


Conduction of heat through the walls of a home accounts for about 10% of the heat gain for the entire building (LBNL 1999). Infiltration through walls causes additional heat gain. This heat gain can be reduced by using “cool” white or reflective wall cladding and finishing materials as described in the guide "Cool Roofs and Walls", by providing shading as described in the guide "Landscaping to Reduce Cooling Load", and by air sealing and insulating the walls. There are several guides in the Building America Solution Center that describe effective ways to air seal and insulate new and existing homes.


The Perfect Wall includes water, air, thermal, and vapor layers with continuous insulation exterior of the sheathing to reduce the condensation potential in the wall.
Figure 1. The “perfect wall” includes a continuous air barrier aligned with an insulation layer that is also continuous and cladding that is separated from the wall assembly by a ventilating air gap; light or reflective cladding would further decrease solar heat gain. (Source: BSC).


Wall Air Sealing

Guides for air sealing walls in new homes include the following guides:

Guides for air sealing walls in existing homes as a retrofit measure include the following:


Wall Insulation

Guides for insulating walls in new homes include the following:

Guides for insulating walls in existing homes as a retrofit measure include the following:


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References and Resources*
Lawrence Berkeley National Laboratory
Publication Date
Report describing a study using parametric computer simulations of 112 single-family and 63 multi-family residential building prototypes to quantify the contributions of building components such as roofs, walls, windows, infiltration, outside air, lighting, equipment, and people to the aggregate...
*For non-dated media, such as websites, the date listed is the date accessed.
Contributors to this Guide

The following authors and organizations contributed to the content in this Guide.

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