USGBC LEED-AP-BD+C - LEED AP Building Design + Construction (LEED AP BD+C)

The Indoor Air Quality Assessment credit under LEED V5 .1 BD+C rating system (Building Design and Construction) seeks to establish better quality indoor air in the building after construction and during occupancy. The credit provides two options for compliance, which cannot be combined 1 . Therefore, Indoor Environmental Quality test results would be required for credit compliance.

 According to the LEED Reference Guide for Building Design and Construction 1 , the Indoor Environmental Quality Credit, Indoor Air Quality Assessment, Option 1. Flush-Out requires the project to perform a building flush-out by supplying a total air volume of 14,000 cubic feet of outdoor air per square foot of gross floor area while maintaining an internal temperature of at least 60°F and no higher than 80°F and relative humidity no higher than 60%. The gross floor area of the building is 1,000 ft2 and the ceiling height is 10 ft, so the required volume of supply air for the entire building flush-out is:

14,000 ft3/sf x 1,000 sf = 14,000,000 ft3

The Whole Building Simulation option is used to meet the Energy and Atmosphere Prerequisite, Minimum Energy Performance for a hospital project. This option involves creating a detailed computer model of the building to simulate its energy performance and identify opportunities for improvement.

Using economizer strategies (A) can offset the additional energy required to increase ventilation. Economizers allow the HVAC system to bring in cooler outdoor air when conditions permit, thus reducing mechanical cooling needs. This method aligns with LEED’s goals for energy efficiency while maintaining indoor air quality. High MERV filters (B) may increase energy usage due to airflow resistance, and reducing duct size (D) can limit airflow efficiency, counteracting ventilation improvements.

The outdoor airflow rate is the amount of outdoor air that is supplied to the building by the ventilation system to dilute indoor air pollutants and provide fresh air for the occupants.  The outdoor airflow rate depends on the ventilation standard that the project follows, which can be either ASHRAE 62.1-2010 or CEN Standard EN 15251-2007 1 . Both standards specify the minimum outdoor airflow rate per person and per unit area for different occupancy types and zones. Therefore, increasing the number of occupants will require an increase in the outdoor airflow rate to maintain the minimum ventilation level. The other variables, such as supply air velocity, system ventilation efficiency, and supply air temperature set point, do not directly affect the outdoor airflow rate, although they may influence the energy consumption and thermal comfort of the ventilation system.

Incorporating precipitation sensors with smart irrigation controllers (C) maximizes irrigation efficiency by adjusting water usage according to real-time weather data and soil moisture levels, reducing unnecessary irrigation during rainfall. This LEED strategy helps conserve water and supports the Water Efficiency (WE) Credit: Outdoor Water Use Reduction . Fixed rates (A), timers (B), and overlapping sprinkler heads (D) do not optimize water based on environmental conditions, leading to possible water waste.

The system boundary that a building life cycle analysis must be defined to account for is the cradle-to-grave stage, which includes the production, construction, use, and end-of-life stages of the building. This stage covers all the inputs and outputs of the building system, such as materials, energy, water, emissions, waste, and maintenance.

Food gardens may be included or excluded from the calculations for Water Efficiency Credit, Outdoor Water Use Reduction, as per the project team’s discretion. If included, food gardens must be calculated using 100% potable water. If excluded, food gardens must be irrigated with 100% captured rainwater, recycled graywater, or water treated and conveyed by a public agency specifically for nonpotable uses. References :

Outdoor Water Use Reduction credit in LEED BD+C: New Construction v4.1 - LEED V5 .1 1

LEED V5 BD+C WE Guide 2

The credit may be achieved by using nonroof measures only, such as shading, paving, and vegetation, to reduce the heat island effect on the site. The credit does not require a highly reflective roof for all projects, but allows for flexibility and trade-offs depending on the climate and design conditions. The project can use the Heat Island Reduction 1 to demonstrate compliance with the credit requirements. The credit is feasible and applicable for this project, and does not need an alternative compliance path. References : SS Credit Heat Island Reduction, LEED V5 Reference Guide for Building Design and Construction 2 3 4

LEED BD+C Location and Transportation (LT) Credit: High Priority Site encourages development in locations with existing infrastructure to promote sustainable land use .

Option 1: Historic District applies to projects located in designated historic districts where at least 75% of land within ½ mile (0.80 km) is previously developed .

Brownfields (Option C) and Federal Renewal Communities (Option D) are separate site categories that fall under different High Priority Site options.

The ¾ mile (1.20 km) radius in Option A is incorrect , as LEED specifically sets the requirement at ½ mile (0.80 km) .

To earn this credit under Option 1 , a project in a historic district must demonstrate that the surrounding land is predominantly redeveloped .

(Source: Official LEED BD+C Reference Manual)