How a home feels is not captured by an energy asset score alone. One measurable driver of thermal comfort is vertical temperature stratification, the difference between the air at head height and at the ankles. ASHRAE Standard 55 flags this as a source of local discomfort and recommends keeping the head-to-ankle difference below 5.4°F (3°C). Here we logged paired sensors at 43 in (1.1 m), head height for a seated person, and 4 in (0.1 m) at the ankles, in two locations over 8 summer days in two locations. (ASHRAE 55 and ISO 7730 share these heights and the 3°C limit.) Sample data shown for illustration.
Summary: Each colour is one location; the two lines are the air temperature at head height (solid, 43 in / seated) and ankle height (dotted, 4 in), and the shaded band between them is the vertical temperature difference your body actually feels. For most of the period the bands are thin, the air is well mixed and comfortable. They widen most in the early morning, when cool air has settled at floor level overnight, and the hallway’s head-to-ankle gap briefly crosses the ASHRAE 55 comfort limit. This is the kind of lived, sub-degree detail that a standardized asset rating cannot see, and that this study sets out to document.
At the orange marker, an occupant answered a brief “right now” thermal-comfort survey (CBE / ASHRAE seven-point scales) while we logged the physical conditions at that instant.
| Outdoor air | 84°F |
| Living Room, head (43 in) | 78°F |
| Living Room, ankle (4 in) | 79°F |
| Head–ankle difference | -0.4°F |
| Thermal sensation | Slightly warm (+1) |
| Thermal comfort | Comfortable |
| Thermal preference | Prefer cooler |
| Air movement | Prefer more |
| Clothing | T-shirt & shorts (~0.4 clo) |
| Activity | Seated, relaxed (~1.0 met) |
Why this matters: indoors holds ~79°F with almost no vertical gradient, cooler than the 84°F outdoors, thanks to the building’s thermal mass, yet still warm enough that the occupant reports feeling slightly warm and would prefer cooler air with more movement. The gap between a reading that looks fine and a person who feels otherwise is exactly what a human-centered evaluation captures, and what an energy asset score alone cannot.
| Location | Mean ΔT | Peak ΔT | Peak occurred | Time over ASHRAE 55 limit |
|---|---|---|---|---|
| Hallway | 0.60°F | 6.28°F | Wed Aug 14, 07:14 | 3% |
| Living Room | 0.67°F | 3.59°F | Tue Aug 13, 23:49 | 0% |
ΔT = (air temperature at 43 in) − (air temperature at 4 in). Positive values mean warmer air above. 15-minute averages shown; threshold evaluated on raw 1-minute data.