8.1 EQ Prerequisites
Key Takeaways
- Minimum Indoor Air Quality Performance requires compliance with ASHRAE 62.1-2016, Sections 4-7 (Ventilation Rate Procedure) or Section 6.4 (natural ventilation).
- Densely occupied spaces (>25 people per 1,000 sf) require CO2 monitors that alarm at 10% above setpoint and are placed 3-6 ft above the floor.
- Environmental Tobacco Smoke (ETS) Control prohibits smoking inside the building and within 25 ft of all outdoor air intakes, operable windows, and entryways.
- Residential projects must post no-smoking signage and weatherstrip exterior doors and windows; multifamily projects must compartmentalize dwelling units.
- Both EQ prerequisites are mandatory for all BD+C rating systems (NC, CS, Schools, Retail, Healthcare, Data Centers, Warehouses, Hospitality).
Why Indoor Environmental Quality Matters
The Indoor Environmental Quality (EQ) category protects the people inside the building. Americans spend roughly 90% of their lives indoors, and indoor pollutant concentrations are often 2-5 times higher than outdoors. The EQ category has the largest direct impact on occupant health, comfort, and productivity, which is why both prerequisites are non-negotiable.
For LEED v4.1 BD+C, the EQ category awards up to 16 points through credits plus the two prerequisites described below. Every BD+C rating system - New Construction, Core & Shell, Schools, Retail, Healthcare, Data Centers, Warehouses & Distribution, and Hospitality - shares the same two prerequisites, although Schools and Healthcare layer on additional minimum acoustic performance requirements covered later in this chapter.
Exam writers love these two prerequisites because they are easy to confuse with optional credits. Memorize the standard name and version exactly, and memorize the 25 ft setback distance verbatim. Reviewers and exam questions both use "ASHRAE 62.1-2016" and "25 ft" as keyword anchors.
Prerequisite 1: Minimum Indoor Air Quality Performance
Intent: Contribute to the comfort and well-being of building occupants by establishing minimum ventilation rates.
Mechanically Ventilated Spaces
Design the ventilation system to meet ASHRAE Standard 62.1-2016, Sections 4-7, using the Ventilation Rate Procedure or a local equivalent (whichever is more stringent). Required calculations include:
- Outdoor air intake rate for each zone using the ASHRAE 62.1 formula:
Vbz = Rp x Pz + Ra x Az - Zone air distribution effectiveness (Ez) based on supply/return configuration
- System ventilation efficiency (Ev) for multi-zone recirculating systems
Naturally Ventilated Spaces
Follow ASHRAE 62.1-2016 Section 6.4 (natural ventilation procedure). Operable openings must:
- Provide an openable area of at least 4% of the net occupiable floor area
- Be located within 25 ft of every occupant in the ventilated zone
- Include a diagrammatic flow path showing how air moves through the space
Mixed-Mode Systems
Mixed-mode systems must satisfy both the mechanical and natural ventilation paths or follow the CIBSE AM10 procedure.
Monitoring Requirements
| Space Type | Required Monitor |
|---|---|
| Mechanically ventilated, densely occupied (>25 people / 1,000 sf) | CO2 sensor, 3-6 ft AFF, alarm at >10% above setpoint |
| Mechanically ventilated, non-dense | Outdoor airflow measurement device (±15% accuracy) |
| Naturally ventilated, densely occupied | CO2 sensor in each thermal zone |
Key exam trap: CO2 monitoring is only mandatory in densely occupied spaces. Designers sometimes voluntarily install CO2 sensors elsewhere, but the prerequisite does not require it.
Prerequisite 2: Environmental Tobacco Smoke (ETS) Control
Intent: Prevent exposure of building occupants, indoor surfaces, and ventilation air-distribution systems to ETS.
Universal Requirements
- Prohibit smoking inside the building.
- Prohibit smoking outside the building except in designated smoking areas located at least 25 ft from all entries, operable windows, and outdoor air intakes.
- Post no-smoking signage within 10 ft of all building entrances.
Residential Project Additions
Residential and hospitality projects layer on additional barriers because tenants control their own units:
- Weatherstrip all exterior doors and operable windows in residential units to minimize air leakage.
- Compartmentalize each dwelling unit using sealed penetrations, gasketed door assemblies, and continuous draft stops between units.
- Conduct a blower-door test (ASTM E779) verifying unit leakage ≤0.23 cfm/sf at 50 Pa pressure differential, or accept a prescriptive path with detailed sealing requirements.
- Vent all common-area smoking rooms (if permitted) directly to the outdoors with the room held at negative pressure of at least 5 Pa (0.02 in. WC).
Why Both Prerequisites Are Non-Negotiable
Unlike credits, prerequisites have no point value but must be earned to achieve certification at any level. A project that scores 80 points but fails ETS Control will not certify. Memorize the 25 ft setback distance and the ASHRAE 62.1-2016 reference - they appear on nearly every BD+C exam form.
A mechanically ventilated open office has a measured occupant density of 32 people per 1,000 sf. Which monitoring device does the Minimum Indoor Air Quality Performance prerequisite require?
A hospitality project includes a designated outdoor smoking area on the rooftop terrace. Which placement satisfies the Environmental Tobacco Smoke Control prerequisite?