The impact depends on the magnitude of the problems. The larger the problems we find in an attic, the greater the potential in comfort and energy savings that can be realized. The example below highlights this issue.
This is a worst case scenario. These photos are taken from a home in Mesa, Arizona. This is a series of three pictures highlighting the impact of missing insulation on comfort and efficiency.
1.The first photo is taken in the attic. Insulation tapers to bare sheetrock. This is the way another insulating company left this job. The builder obviously never inspected the attic.
2. The second picture is a temperature gun showing the surface temperature of the sheet rock in the living room. The surface temperature is 111℉. You can be sure this is an uncomfortable home with high utility bills.
3. The third photo is taken in the living room with an infrared camera in which the color white represents higher temperatures. The heat from the attic is radiating into this home and driving up the utility bills and compromising comfort.