LEED (BD+C)- Indoor Environmental Quality Prerequisite: Minimum indoor air Quality Performance

Indoor air quality (IAQ) is an important consideration in any building design and operation. It has a direct impact on the health, comfort, and well-being of occupants. One way to ensure good IAQ is to follow the LEED (Leadership in Energy and Environmental Design) certification system, which provides a framework for building owners and operators to implement sustainable practices. In this article, we will discuss the step-by-step method to comply with the LEED credit related to indoor air quality.

Minimum Indoor Air Quality Performance (Pre-requisite): This credit requires compliance with the ASHRAE 62.1 ventilation standard, which specifies the minimum outdoor air ventilation rates for various occupancy types. The ventilation rates must be maintained and verified through testing.

Step-by-Step Method to Comply with the Minimum Indoor Air Quality Performance Prerequisite:

In this section, we will discuss the step-by-step method to comply with the Minimum Indoor Air Quality Performance credit.

Step 1: Determine the Occupancy Categories

The first step is to determine the occupancy categories for each zone in the building. The occupancy categories are defined by ASHRAE 62.1 and are based on the activities that take place in the zone. Examples of occupancy categories include offices, classrooms, and laboratories. In example, the occupancy categories for the 11th floor are Dwelling unit – studio or one-bedroom and Bedroom/living room.

Step 2: Determine the Zone Floor Area and Population

The next step is to determine the floor area and population for each zone. This information is needed to calculate the ventilation rates for each zone. In example, the zone floor areas and populations are as follows:

Hotel Block: 5,720 sq ft, 48 occupants
Residential: 3,266 sq ft, 28 occupants

Step 3: Determine the Zone Air Distribution Effectiveness

The zone air distribution effectiveness (ADE) is a measure of how well the supply air is distributed throughout the zone. It is used to calculate the effective ventilation rate for each zone. In example, we assume an ADE of 1.0 for both zones.

Step 4: Determine the Zone Outdoor Airflow

The zone outdoor airflow is the amount of outdoor air that is supplied to each zone. It is based on the ventilation rate per person (Rp) and the occupancy of the zone. In example, we assume a ventilation rate of 15 cfm per person, which results in the following zone outdoor airflows:

Hotel Block: 48 occupants x 15 cfm/person = 720 cfm
Residential: 28 occupants x 15 cfm/person = 420 cfm

Step 5: Determine the Zone Primary Airflow

The zone primary airflow is the total supply air that is delivered to the zone. It is based on the zone outdoor airflow, the zone air distribution effectiveness, and any recirculated air. In example, we assume that there is no recirculated air in either zone. Therefore, the primary airflow for both zones is equal to the zone outdoor airflow multiplied by the zone air distribution effectiveness.

Hotel Block: 720 cfm x 1.0 = 720 cfm
Residential: 420 cfm x 1.0 = 420 cfm

Step 6: Verify the Ventilation Rates

The final step is to verify that the ventilation rates for each zone meet the ASHRAE 62.1 standard. This is done through testing and measurement of the airflow rates.

Indoor air quality is a crucial factor in building design and operation. Good IAQ has a direct impact on the health, comfort, and well-being of occupants. The LEED certification system provides a framework for building owners and operators to implement sustainable practices, including ensuring high-quality indoor air. To achieve the LEED credit for indoor air quality, building owners and operators must comply with two pre-requisite credits and one optional credit. The Minimum Indoor Air Quality Performance credit requires compliance with the ASHRAE 62.1 ventilation standard, which specifies the minimum outdoor air ventilation rates for various occupancy types. By following the step-by-step method we have outlined, building owners and operators can ensure they are meeting the necessary requirements to achieve compliance with this credit.