Thermal Safety temperatures

Path 1:

Psychrometry /

Heat Index

Referenced from RELi 2.0

Except as noted below,
maintain indoor temperatures at or below (103) degree heat
index in hot seasons. In cold seasons maintain interior
building temperature at or above (50) degrees. Manage other
space to prevent freezing of water.

General residential buildings, facilities and areas

: Maintain a maximum (90°F/32.2°C) degree (the “Extreme
Caution” threshold) heat index temperature during the hot
season.

For Hospitals and Nursing homes:
Thermal requirements for hospitals and nursing
homes—maintaining an (81°F/27°C) degree heat index maximum
during the hot season / (71°F/21.7°C) degree minimum during
the cold season (required by US federal law for nursing
homes)—typically cannot be maintained passively, and must
be maintained with backup power.

All commercial buildings not falling into the mission
critical or Fundamental Community Service Organization

category must maintain an interior temperature of not more
than (103°F/39.4°C) degrees heat index. These requirements
are waived should the outside temperature rise to be higher
than (103) degrees (the “Danger” threshold) on the Heat
Index.

No hours during the summertime analysis period are
permitted to exceed the heat index temperatures above.
Refer to the Psychrometric chart in Figure P3-1 for
corresponding Dry Bulb temperatures and Humidity Ratios.

Thermal Safety temperatures

Path 2:

Psychrometry /

WBGT

Cooling (Summer)
:

For Commercial buildings or buildings without overnight
occupancy: No hours during the summertime analysis period
permitted to exceed above either the 88°F (31°C) WBGT
overheating threshold indicated on the Psychrometric chart
in Figure P3-1.

For Residential buildings or building with overnight
occupancy (such as lodging): No hours during the summertime
analysis period permitted to exceed above either the 82.5°F
(28°C) WBGT overheating threshold indicated on the
Psychrometric chart in Figure P3-1.

Heating (Winter)
: No hours during the wintertime analysis period permitted
to fall below 50°F (10°C) (residential or non-residential
buildings) dry-bulb air temperature on the psychrometric
chart in Figure 3-1.

For hospitals and nursing homes: It is assumed that they
will have sufficient backup power to enable them to meet
their legal obligations—at no point during the year are
they permitted to exceed above 81°F (27°C) on the Heat
Index or fall below 71°F (21.7°C) on the Heat Index. This
is a backup power requirement and is separate from this
passive survivability requirement.

For more information on the CBE Thermal Comfort Tool:

https://cbe.berkeley.edu/research/thermal-tool.htm#publications

Thermal Safety temperatures

Path 2: SET

Cooling: Not to exceed 9 °F SET-days (216 °F SET-hours)
above 86°F SET for residential buildings. (Metric: Not to
exceed 5°C SET-days (120 °C SET-hours) above 30°C SET for
residential buildings.)

Cooling: Not to exceed 18 °F SET-days (432°F SET-hours)
above 86°F SET for non-residential buildings. (Metric: Not
to exceed 10°C SET-days (240 °C SET-hours) above 30°C SET
for non-residential buildings.)

Heating: Not to exceed 9 °F SET-days (216 °F SET-hours)
below 54° SET for all buildings. (Metric: Not to exceed 5°C
SET-days (120 °C SET-hours) below 12°C SET for all
buildings.)

°F SET-days and °F SET-hours are degree-days and
degree-hours in Fahrenheit degrees, using SET rather than
air temperature.

°F SET hours are calculated as follows:

Cooling: Sum of the difference between the zone calculated
SET and 86°F, only if the zone SET is greater than 86°F,
for all hours of the extreme hot week.

Heating: Sum of the difference between 54°F and the zone
calculated SET, only if the zone SET is less than 54°F, for
all hours of the extreme cold week.

Use the same method for °C SET-days and °C SET-hours.

Path 3: Passive House certification

Habitable temperatures are not defined for Passive House,
but it is assumed that buildings achieving a Passive House
level of energy performance will meet the habitable
temperatures requirements called for in Paths 1, 2, or 3.
(Note that in addition to meeting Passive House
requirements, to fulfill this credit requirement operable
windows or other means of natural ventilation must be
provided as per Figure 3.0, below.)

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