♨️ The heat is on

Yesterday I wrote about the ways heat moves into our homes through conduction, convection and radiation.

  • Today we’ll look at some actual numbers for a recent home performance test.

Why it matters: Knowing where the heat is getting in helps us develop strategies to keep it out.

🔬 Zoom in: Using an infrared camera, we can “see” the heat and measure it under normal conditions and while running the blower door test (BD).

While the Blower Door is running, the heat from the attic easily goes around the can light into the house.

🧮 By the numbers: Here are the temperatures we measured inside the house plus a tip for addressing it.

  • Outside temperature was 103F. Attic temperature was 130F.

👉 Around the door to the garage

  • Normal = 92.5F, BD = 100.2F
  • Weatherstripping this door will help.

👉 Pull down attic stairs

  • Normal = 102.4F, BD = 119.3F
  • Attic access inside your living space (i.e. not in your garage) needs to be addressed with an insulated and sealed attic tent.

👉 Recessed can lights

  • Normal = 101.8F, BD = 125.8F
  • Can lights need to be air sealed to prevent this leakage.

👉 Fur downs

  • Normal = 91.9F, BD = 102.4F
  • Any change in ceiling height (with a fur down or in a hallway or bathroom) usually means the framing in the attic has created gaps and cracks where heat can get in.

✅ For your Smart Homeowner list

  • Walk around your house and notice any penetration in the ceiling that’s underneath unconditioned attic space — first floor penetrations immediately under a second floor aren’t an issue.
  • Those are the most likely places where you’re fighting against heat trying to get into the house.



P.S. I’ve been booking more 20 minute Home Energy & Performance Consults. Let me know if you’re ready for help.

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