ASHRAE Journal - July 2019 - 14

TECHNICAL FEATURE

temperatures and less strict space temperature
control.7 Warmed blankets have been proven effective in reducing cold discomfort in elder patients.8
Research in PCS in health care has mainly focused
on specialized applications; for example, comparing the effects warm forced-air, localized radiant
heat, and conductive bedding approaches to prevent patient hypothermia during and right after
surgery.9,10 Further research is needed to evaluate
the effectiveness of PCS in a broad range of healthcare applications and on their integration into
reliable, low-energy HVAC environmental design
strategies.
Research is also needed to determine the effects
of psychological and work-related factors, and
medical conditions on thermal comfort (Table 1).

Case Study: Predicting Thermal Comfort of
Nurses in a Hospital Ward Environment

TABLE 2 Summary of data and results.11
DATA/
RESULTS

COMMENTS

Personal Complete Work Schedule With the Following Activities Alternating
Activity Throughout a Typical Day:
* Shift Change (0.5 Hour)
* Patient Round: Care Taking (1.5 to 2.0 Hours)
* Patient Round: Medication (0.5 Hour)
* Patient Round: Control (0.5 Hour)
* Medication Preparation (0.5 Hour)
* Update Patient Stats (1.5 hour to 2.0 Hours)
* Coffee Break (0.5 Hour)
* Break (0.5 Hour)
Personal Obligated Uniform
Clothing Additional Vest as Part of the Uniform
Objective Two Wards (East and West) With One Nursing Station Per Ward
Measurements Preliminary Measurements Detected No Thermal Anomalies in Wards
Thermal Conditions in Each Ward Were Uniform
Monitoring Stations Were Placed at Several Locations in Both Wards
Approximate Ranges of Air Temperature in wards (From Box Plot)
* East Ward: Summer [21.5°C (71°F), 24.8°C (77°F)],
Autumn[20.2°C (68°F), 23.5°C (74°F)]

As an example of the use of Standard 55-2017
in a health-care setting, the following case study
* West Ward: Summer [22.0°C (72°F), 25.6°C (78°F)],
focuses on nurses as representative occupants for
Autumn [21.0°C (70°F), 23.3°C (74°F)]
thermal comfort analysis. Nurses were selected
* Warm Temperature Excursions Above These Ranges Are Experienced
for this case study because data is available from
in Both Wards But These Are More Pronounced in the West Ward
a field study correlating objective measurements
Outdoor Summer Temperature Ranges: [8.4°C (47°F), 32.2°C (90°F)]
and subjective feedback from nurses in a ward.11
Autumn Temperature Ranges: [-0.4°C (31°F), 18.7°C (66°F)]
The data validates the thermal comfort analysis.
Subjective Thermal Sensation (TSV):
Unfortunately, the field study did not include any
Questionnaires
* Summer: Slightly Warm to Warm
data on patients or other occupants. The case study
* Autumn: Neutral
is not intended to use nurses as the surrogate for
Thermal Acceptability (TAV):
determining the thermal comfort parameters for
* Summer: Slightly Unacceptable
the wards, thus prioritizing the thermal comfort of
* Autumn: Slightly Acceptable
nurses over patients.
Self-Assessed Work Performance (SAWP):
* Summer: Obstructive to Slightly Obstructive
According to Standard 55-2017, thermal comfort
* Autumn: Slightly Conductive
analyses need to be conducted for each representative occupant in a thermal zone. The overlapping
TSV vs. Neutral Temperature from Correlation: 21.8°C (71°F)
Temperature Temperature Range from Correlation for Slightly Cool to Slightly Warm
and adjusting of individual comfort zones can, in
Thermal Sensation: [20.3°C (69°F), 23.3°C (74°F)]
turn, be used to determine thermostat setpoint
ranges. If thermal comfort conditions cannot be
The analysis of thermal comfort of patients deserves
provided for every occupant, then design and operational solutions need to be explored. These may include, special consideration. At a minimum, it should include
the following factors:
combining room environmental systems (e.g., radiant
* Personal factors affecting thermal comfort: age,
and air systems), adjusting the thermal zoning, or providing personal or task conditioning. It should be identi- type of medical service and medical condition, effect of
medication, length of stay, bedding/clothing, degree of
fied when the analyses do not work to keep occupants
comfortable or when occupants are excluded. The whole mobility, and posture.
* Thermal environmental: operative temperature,
process needs to be properly documented.
14

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ASHRAE Journal - July 2019

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