Thermal Comfort
| Table Header | Table Header |
|---|---|
|
2 |
Improves occupant satisfaction and can improve energy performance |
|
1 |
One to three months for repairs and controls adjustments |
|
1 |
Minor upgrades and repairs, such as air sealing and diffuser adjustment or replacement |
|
|
FAC, GEN, FIN |
The most prevalent complaint concerning IEQ is thermal comfort, which is a product of environmental conditions (temperature, humidity, air flow, and radiant temperature), personal preferences, metabolism, activity, age, attire, and cultural expectations.
In a 2009 survey of Dept of State staff, 94% reported that occupants complain about being too cold and 91% reported that occupants complain about being too hot.16
ANSI/ASHRAE Standard 55 identifies indoor thermal environmental ranges that are acceptable to approximately 80% of occupants when attired appropriately for the climate and season, based on global laboratory and field research. ASHRAE’s acceptable ranges of temperature and relative humidity for mechanically heated and cooled spaces are shown in Table 1. A wider range of conditions is comfortable in naturally conditioned spaces (Resources: ANSI/ASHRAE Standard 55-2010 | ashraerp.com).
Providing individual control over environmental factors is the most effective way to ensure that all occupants remain comfortable. However, individual control is frequently not possible in buildings with central conditioning systems. In such cases, careful management of temperature and humidity levels is the key to achieving high levels of occupant satisfaction.
Strategies for improving thermal comfort include:
- Adjusting humidity and temperature setpoints to fall within ANSI/ASHRAE-recommended ranges (see Table 1)
- Changing temperature setpoints to meet guidance put forth by the Secretary of State, which recommends cold weather settings of 20–23.5 degrees Celsius (°C) (68–75 degrees Fahrenheit (°F)) and during warm weather settings of 22.5–26°C (73–79°F), assuming 30-60% relative humidity
- Adjusting HVAC schedules to ensure that heating and cooling systems scheduled for night setbacks turn on early enough to heat or cool the space before occupants arrive
- Allowing a seasonally-appropriate dress code
- For buildings with BAS systems, incorporating alarm functions to notify FM staff when a zone drifts outside of the recommended ranges
Table 1: Acceptable temperature and humidity ranges for thermal comfort according to ANSI/ASHRAE Standard 55-201017
