To assess how well the building is performing for the occupants, in particular with regards to indoor air quality and comfort.
Conduct an occupant satisfaction survey and/or an indoor air quality evaluation.
For the occupant satisfaction survey, regular building occupants must be surveyed. The required number of responses that must be received is outlined in Figure 1.
For the indoor air quality evaluation, test for any of the following contaminants:
- Inorganic Contaminants:
- Carbon Monoxide (CO)
- Carbon Dioxide (CO2)
- Ozone (O3)
- Volatile Organic Compounds:
- Acetaldehyde (75-07-0)
- Benzene (71-43-2)
- Styrene (100-42-5)
- Toluene (108-88-3)
- Naphthalene (91-20-3)
- Dichlorobenzene (1,4-) (106-46-7)
- Xylenes-total (108-38-3, 95-47-6, and 106-42-3)
- Formaldehyde (50-00-0)
- Total volatile organic compounds (TVOC) (as defined in ISO 16000-6)
Points are awarded based on the results from the CO2 and TVOC measurements.
Take the indoor air measurements in locations representative of all occupied spaces, within the breathing zone (between 3 and 6 feet (900 and 1800 millimeters) above the floor), during normal occupied hours, under typical minimum ventilation conditions.
Conduct the survey at least once per year, using the Arc Platform, and calculate an Occupant Satisfaction Score for the project.
Conduct at least one indoor air quality evaluation per year. Input measured contaminant levels into the Arc Platform and calculate a CO2 Score and TVOC score for the project.
Obtain a minimum Human Experience Score of 40. Additional points for this prerequisite are awarded for Human Experience Scores above 40, according to Table 1.
The Human Experience Score is based on three components which are weighted differently:
- Occupant satisfaction score (50% weighting)
- CO2 score (25% weighing)
- TVOC score (25% weighting)
Table 1. LEED Points for Human Experience
Human Experience Score
Figure 1. Required Response Rates as a Product of Building Occupancy
Equation: Response rate= 100 * (0.25 / square root (occupancy / 500))
Occupant satisfaction score
The occupant satisfaction score rates the satisfaction occupants have with the building against satisfaction of occupants of comparable LEED certified buildings.
The score is a value from 1-100 based on the project’s average occupant satisfaction level taking and the variance in the occupant responses.
Occupant Satisfaction Score calculation
To calculate an occupant satisfaction score, the following data is required. All data is collected via the occupant satisfaction survey. At least one survey every 365 days must be conducted:
- Number of regular building occupants and visitors
- For Hospitality projects, number of hotel or lodging guests (these occupants may be excluded from the survey)
- Occupant satisfaction level (for each survey response)
The projects occupant satisfaction score is calculated by taking the average of the satisfaction levels for each building occupant that completes the survey, and considering the variance in the responses, using Equation 1.
Equation 1: Occupant satisfaction score = (Average occupant satisfaction level x 10) - variance in occupant satisfaction level
The CO2 score rates the building’s CO2 levels against the industry benchmark level of 1000 ppm.
The score is a value from 1-100 based on the project’s average 95th percentile CO2 value.
CO2 score calculation
To calculate a CO2 score, the following data is required:
- Measurement location
- Date and time for each measurement
- Measured CO2 concentration (ppm)
The 95th percentile value for each location (CO295th) is calculated. The 95th percentile is the CO2 value where 95% of the data falls below.
An average CO295th value is calculated for the indoor environmental quality evaluation.
The project’s average CO295th value is then input into the CO2 scoring function (see Figure 2) to produce a CO2 score for the project.
Figure 2. CO2 scoring function
The CO2 scoring function was developed based on the industry benchmark level of 1000 ppm.
The TVOC score rates the building’s TVOC levels against the industry benchmark level of 500 µg/m3.
The score is a value from 1-100 based on the project’s maximum TVOC value.
TVOC score calculation
To calculate a TVOC score, the following data is required:
- Measurement location
- Measurement date(s)
- Start and end time(s) for each measurement
- Measured TVOC concentration (µg/m3)
An average TVOC level (TVOCavg) is calculated for each location by averaging all of the TVOC measurements taken at that location during the indoor air quality evaluation.
A maximum TVOC level (TVOCmax) is determined by taking the highest TVOCavg value for the indoor environmental quality evaluation.
The project’s maximum TVOC level (TVOCmax) is then input into the TVOC scoring function to produce a TVOC score for the project.
The TVOC scoring function was developed based on the LEED TVOC limit of 500 µg/m3.