International. Strategies to improve ventilation and filtration in buildings have been a priority over the past year as teams work on re-entry plans and adjustments to better support occupant health in light of the COVID-19 pandemic.
Now, with the addition of airborne transmission as part of the Centers for Disease Control and Prevention's (CDC) coronavirus guidance, a renewed focus will be placed on best practices for improving indoor air quality in existing buildings.
Indoor air quality management is an important part of running a LEED building. Earlier this year, the USGBC outlined existing LEED strategies and resources to help guide teams in improving indoor environments. The USGBC then launched four LEED Safety First pilot credits for buildings in response to COVID-19. These pilot credits offer best practices that align with public health and industry guidance, including one on indoor air quality.
Here's how the new credit and Arc support existing buildings, as well as indoor air quality requirements under LEED v4.1:
Safety First Pilot Credit: Indoor Air Quality Management During COVID-19
This pilot credit builds on existing LEED strategies and requires construction teams to ensure indoor air quality systems are working as designed. It also encourages adjustments in ventilation that can minimize the spread of the coronavirus through the air. The credit encourages increasing the percentage of outside air when appropriate and increasing air filtration by using MERV 13 or 14 filters when possible. Additional requirements are continuous monitoring and evaluation of indoor air quality. Read the full credit requirements.
Indoor air quality measurement
The new Arc Re-Entry pilot credit recognizes a coordinated effort to reduce the risk of infection by taking several steps, including measuring and analyzing indoor air quality. Measurements, while unable to detect infectious agents, are useful in helping building managers assess whether there is adequate ventilation in a space. Arc helps track key areas identified by the scientific literature described in the Arc Reentry Guide.
Relative humidity: Relative humidity between about 40% and 60% has been correlated with lower disease transmission.
CO2 concentration: High concentrations of CO2 indoors indicate inadequate ventilation or overcrowding. Building standards (e.g. ASHRAE 62, EN 16798-1) have consistently sought to encourage increased ventilation to dilute indoor contaminants and pathogens. High levels of CO2 concentration have also been correlated with reduced cognitive performance and alertness.
Particle concentration: The presence of relatively high concentrations of particles may indicate inadequate ventilation or filtration. There is limited evidence that particulate matter concentrations may be related to the rate of viral spread under specific circumstances, according to data from northern Italy. High concentrations of particles in the environment have been linked to an increased incidence of chronic respiratory diseases, such as COPD and asthma, and a host of other health problems. These respiratory conditions can, in turn, exacerbate the susceptibility and impact of the coronavirus on people.
LEED v4.1 Indoor Air Quality Requirements
Existing buildings wishing to obtain LEED v4.1 certification must meet the minimum indoor air quality requirement, which is intended to benefit occupants and set minimum standards for indoor air quality. Projects must maintain the equipment and components of the ventilation system and, at the same time, follow the requirements described for spaces with mechanical and natural ventilation.
The second indoor air quality requirement is described in the Indoor Environmental Quality Performance Credit.
The intention is to assess how well the building is performing for the occupants, especially with regard to indoor air quality and comfort. Projects receive points based on the results of CO2 and TVOC measurements.
