A03: Ventilation Effectiveness

(Required)

INTENT

Prevent indoor air quality issues through the provision of adequate ventilation.

SUMMARY

This WELL feature requires projects to bring in fresh air from the outside through mechanical and/or natural means in order to dilute human- and product-generated air pollutants.

ISSUE

Poorly ventilated spaces contribute to symptoms — such as headache, fatigue, dizziness, nausea, cough, sneezing, shortness of breath and eye, nose, throat and skin irritation — collectively called sick building syndrome (SBS). The economic costs of SBS in under-ventilated buildings are significant and far exceed the energy-related cost savings. Poor ventilation is also linked to increased rates of absences, higher operational costs and decreased productivity. One U.S.-based study reported that the sick leave attributable to insufficient provision of fresh air in buildings is estimated to be 35% of total absenteeism.

SOLUTIONS

Many indoor and outdoor sources of air pollution emit particulate matter and volatile organic compounds (VOCs) that can cause discomfort and trigger asthma and eye, nose and throat irritation. In order to maintain healthy indoor environments for building users, it is necessary to provide sufficient ventilation required to maintain acceptable air quality. In addition to proper HVAC system design, mechanically ventilated projects need to perform regular system maintenance as inadequate maintenance is associated with reduced ventilation performance and poorer indoor air quality and thermal conditions. For naturally ventilated spaces, it is necessary to ensure that adequate outdoor air quality and noise levels are met.

IMPACT

Proper design and operation of a ventilation system is essential for supporting indoor air quality and plays a fundamental role in creating healthy buildings.

REQUIREMENTS

Part 1

Ensure Adequate Ventilation

Verified by MEP

For All Spaces except Dwelling Units

Choose between the following:

1. Mechanically ventilated spaces:

Projects utilizing mechanical ventilation comply with ventilation supply and exhaust rates set in one of the following: 

1. ASHRAE 62.1-2010 or any more recent versions (Ventilation Rate Procedure or IAQ Procedure).

2. CEN Standards EN 15251:2007 and EN 16798-3:2017 or any more recent versions. The requirements of CEN Standard EN 15251:2007 must be met as well as the performance requirements of CEN Standard EN 16798-3:2017 related to ventilation and room conditioning systems (excluding sections 7.3, 7.6, A.16 and A.17). Note that projects must meet Category I or II as described in the standards.

3. AS 1668.2-2012 or any more recent version. Note that projects that wish to comply with AS 1668.2 must assume a minimum density of 16 m² [170 ft²] per person.

4. CIBSE Guide A: Environmental Design, version 2007 or any more recent version.

2. Naturally ventilated spaces:

Projects using natural ventilation only (no mechanical ventilation) meet the following requirements:

1. Outdoor PM_2.5, PM₁₀, carbon monoxide and ozone levels within 4 km [2.5 mi] of the building are compliant with the levels specified in Feature A01: Air Quality Standards for at least 95% of all hours in the previous year. 

2. One of the following design criteria:

   1. Natural Ventilation Procedure in ASHRAE 62.1-2010 or any more recent version (as appropriate for number of floors above grade).
   2. CIBSE AM10: Natural Ventilation in Non-Domestic Buildings (2005 or any more recent version) section 2.4 – Natural ventilation strategies and chapter 4 – Design Calculations.

3. Naturally ventilated spaces:

Note: Projects pursuing this strategy are limited in WELL Certification level to Gold, regardless of total points achieved.

Projects using natural ventilation only (no mechanical ventilation) meet the following requirements:  

1. Outdoor air meets the following thresholds as an average for the previous year:

   1. PM_2.5 less than 25 μg/m³.
   2. PM₁₀ less than 50 μg/m³.

2. One of the following design criteria:

   1. Natural Ventilation Procedure in ASHRAE 62.1-2010 or any more recent version (as appropriate for number of floors above grade).
   2. CIBSE AM10: Natural Ventilation in Non-Domestic Buildings (2005 or any more recent version) section 2.4 – Natural ventilation strategies and chapter 4 – Design Calculations.

4. Naturally ventilated spaces:

Note: Projects pursuing this strategy are limited in WELL Certification level to Silver, regardless of total points achieved.

Projects using natural ventilation only (no mechanical ventilation) meet the following requirements:  

1. Outdoor air meets the following thresholds as an average for the previous year:

   1. PM_2.5 less than 35 μg/m³.
   2. PM₁₀ less than 70 μg/m³.

2. One of the following design criteria:

   1. Natural Ventilation Procedure in ASHRAE 62.1-2010 or any more recent version (as appropriate for number of floors above grade).
   2. CIBSE AM10: Natural Ventilation in Non-Domestic Buildings (2005 or any more recent version) section 2.4 – Natural ventilation strategies and chapter 4 – Design Calculations.

5. Mixed-mode ventilated spaces:

Projects using mixed-mode ventilation meet one of the following requirements:  

1. Project complies with the requirements set for naturally ventilated spaces when mechanical system is not in use and the requirements for mechanical ventilation when the mechanical system is in use. Mechanical ventilation must be operated when outdoor air quality conditions are above the limits in Feature A01: Fundamental Air Quality. 

2. Operate with mechanical ventilation CIBSE AM13: Mixed Mode Ventilation, version 2000 or any more recent version.

For Dwelling Units

Choose between the following:

1. Mechanically ventilated spaces:

Projects utilizing mechanical ventilation comply with ventilation supply and exhaust rates set in one of the following: 

1. ASHRAE 62.2-2016 (continuous or intermittent ventilation system requirements) or any more recent version.
2. CEN Standards EN 15251:2007 or any more recent version. Note that projects must meet Category I or II as described in the standards.
3. AS 1668.2-2012 or any more recent version.
4. CIBSE Guide A: Environmental Design, version 2007 or any more recent version.

2. Naturally ventilated spaces:

Projects using natural ventilation only (no mechanical ventilation) meet the following requirements:

1. Outdoor PM_2.5, PM₁₀, carbon monoxide, ozone and nitrogen dioxide levels within 4 km [2.5 mi] of the building are compliant with the thresholds specified in Feature A01: Air Quality Standards for at least 95% of all hours in the previous year. 

2. One of the following design criteria:

   1. Natural Ventilation Procedure in ASHRAE 62.1-2010 or any more recent version.
   2. CEN Standards EN 15251:2007 or any more recent version. Note that projects must meet Category I or II as described in the standards.
   3. CIBSE Guide A: Environmental Design, version 2007 or any more recent version.

3. Naturally ventilated spaces:

Note: Projects pursuing this strategy are limited in WELL Certification level to Gold, regardless of total points achieved.

Projects using natural ventilation only (no mechanical ventilation) meet the following requirements:  

1. Outdoor air meets the following thresholds as an average for the previous year:

   1. PM_2.5 less than 25 μg/m³.
   2. PM₁₀ less than 50 μg/m³.

2. One of the following design criteria:

   1. Natural Ventilation Procedure in ASHRAE 62.1-2010 or any more recent version.
   2. CEN Standards EN 15251:2007 or any more recent version. Note that projects must meet Category I or II as described in the standards.
   3. CIBSE Guide A: Environmental Design, version 2007 or any more recent version.

4. Naturally ventilated spaces:

Note: Projects pursuing this strategy are limited in WELL Certification level to Silver, regardless of total points achieved.

Projects using natural ventilation only (no mechanical ventilation) meet the following requirements:  

1. Outdoor air meets the following thresholds as an average for the previous year:
   1. PM_2.5 less than 35 μg/m³.
   2. PM₁₀ less than 70 μg/m³.
2. One of the following design criteria:
   1. Natural Ventilation Procedure in ASHRAE 62.1-2010 or any more recent version.
   2. CEN Standards EN 15251:2007 or any more recent version. Note that projects must meet Category I or II as described in the standards.
   3. CIBSE Guide A: Environmental Design, version

Part 2

Conduct System Balancing

Verified by MEP & Contractor

For All Spaces

Mechanically ventilated spaces:

To verify compliance with the ventilation rate requirements specified in Part 1: Ensure Adequate Ventilation, the following requirements are met or are scheduled to be met (as applicable):

1.  Newly installed mechanical ventilation system or ventilation system that undergoes significant alterations is tested and balanced in accordance with ASHRAE 111.

2. Existing mechanical ventilation system is tested and balanced every five years to verify that the minimum ventilation rates (as determined in Part 1: Ensure Adequate Ventilation) are within ± 10% of the minimum design values. 

3. Projects using the elevated air speed method for thermal comfort verify that air speed complies with design specifications.

 

Note: Reasons for adjustment or modification of the mechanical ventilation system that result in a requirement for system rebalancing include significant building alterations, significant changes in occupant density, changes in building use or occupancy category or other changes inconsistent with system design assumptions.

© International WELL Building Institute