Indoor Environmental Quality Flashcards
Floor Area Calculations & Floor Plans
Based on % of Floor Area
Space Categorization
Identify User Type & Activity Performed
Create table of all rooms & spaces and identify:
- Ventilation Strategy
- Net occupiable space
- Occupancy Category
- Polluting Level (if foreign project) using CEN Standard
- Design Occupancy
Occupied vs Unoccupied
Occupied : Enclosed for human activity
Unoccupied : Only for a Short Period of Time (Inactive)
Regularly Occupied vs Non-regularly Occupied
Regularly : 1 hr of continuous occupancy per person per day
Non-regularly : Pass Through or used less than one hour per person per day
Occupied Space Sub-categories
Individual : Distinct Tasks are Performed
Shared Multi-occupant : Collaborative Tasks by a Group
Density of Occupied Space
Dense : 25 persons / 1,000 ft2 (93 m2) OR 40 ft2 (3.7 m2) or less per person
Tricky Spaces
Residential Auditoriums Gyms Transport Terminals Dorms/Military Barracks Industrial Facilities
Mechanically Ventilated Spaces : Case 1
CASE 1 : Systems able to meet required outdoor airflow rates
Option 1 : ASHRAE Standard 62.1-2010
- Determine minimum outdoor air intake (more stringent between ASHRAE or local standard)
- Meet the requirements of Section 4-7
Option 2: CEN Standards EN 15251-2007 & EN 13779-2007 (Foreign Projects)
- Determine minimum outdoor air requirements 15251-2007
- Meet requirements for 13779-2007 for ventilation
Mechanically Ventilated Spaces : Case 2
- Complete engineering assessment of the system’s max outdoor air delivery rate
- Supply max to reach minimum setpoint in Case 1
- 10 ft3/min per person
Naturally Ventilated Spaces
- Determine minimum using ASHRAE Standards 62.1-2010 or local equivalent
- Use flow diagram in CIBSE
Monitoring : Mechanically Ventilated Spaces
- Provide device to measure the min outdoor air intake flow with +/- 10% accuracy
- Alarm when airflow rate value exceeds 15% from setpoint
- Monitoring does not have to be dedicated to project spaces, but each system must have a measurement device
- Monitor can be installed at the outdoor air vent…but ventilation rates must be calculated for each terminal device
Min Indoor Air Quality Performance
Pre-Requisite
Includes Ventilation & Monitoring
Monitoring : Naturally Ventilated Spaces
Comply with 1:
Option 1
- Direct exhaust airflow device with +/- 10% of the design min exhaust airflow rate
- Alarm when airflow varies by 15% or more from setpoint
Option 2
- Provide automatic indication devices on all openings
- Alarm when openings are closed
Option 3
- Monitor CO2 within each thermal zone
- Installed between 3-6 feet above the floor
- Alarm with audible or light to alert when varies to 10% or more from setpoint
- Setpoints outlined as in ASHRAE 62.1-2010, Appendix C
Behind the Intent of IAQ
Requirements vary by:
Space Type
Building Type
Project Type
Ventilation element as part of the pre-req credit required if HVAC is part of landlord space or controlled by the tenant, but Monitoring is only required for the systems in the project scope of work.
Existing HVAC systems may need a performance assessment.
Determine HVAC System Configuration
- Zone Configuration
- Ventilation Design
- Air Temperature
- Supply System
Calculate Required Outdoor Airflow (Option 1)
- Ventilation Rate Procedure for each system
- Include all occupied spaces
- Perform Ventilation Rate Procedure Calculations
- Document Assumptions
- Respond to any varying conditions
Meeting Minimum Requirements (Option 1)
- Compliance with ASHRAE Standard 62.1-2010, Section 4-7
- Confirm project is in area for fine particulate matter and filters of MERV 11 or higher have been installed
- Confirm if ozone exceeds the concentration of 0.107 ppm and will have air-cleaning devices installed
Naturally Vented Spaces (& Mixed-Mode Systems)
- Confirm effectiveness with CIBSE
- Do flow chart path for the project
- Determine ceiling heights
- Locate vent openings and size
- Use ASHRAE 62.1-2010 to determine calculation results (Section 6.4 doesn’t apply if project has been approved by local authority)
- Confirm exhaust vent requirements
- Determine if exceptions are warranted
Natural Vented Spaces Monitoring
- Airflow devices installed at the exhaust locations
- Provide cutsheets, plans and control sequences and diagrams
- Identify all windows, louvers and vents
- Alarm for each opening
- C02 sensors in each thermal zone (breathing zone)
- Determine setpoints using ASHRAE 62.1
- Alarm for each sensor when exceeded by 10%
Shared Ventilation Systems
- Account for total system population, area, supply air and outdoor air volume
- Perform floor area weighted calculations to determine the required outdoor air ventilation rates
- % of outdoor air by volume may be used if provided to the project space to calculate requirement
- Vent rate only required for the project space
Existing Ventilation Systems
If project space cannot meet requirements, Case 2 applies.
- Provide engineering assessment
- Determine max outdoor air volume
- Confirm that ventilation system provides max amount of outdoor air at 10 ft3/min/person
Natural Ventilation Exceptions
Mechanical systems must be included unless one of the following applies:
- Vent openings are permanently open
- Include controls that prevent them from being closed during occupation
- Zone not served by heating or cooling equipment
- System is engineered and approved by local authority
Ventilation Zone Defined by ASHRAE 62.1-2010
Similar:
- Occupancy Category
- Occupancy Density
- Zone Air Distrbution Effectiveness
- Zone Primary Airflow per unit area
Mechanical Ventilation Systems
Single-zone : one system serving one type, mixed ventilation + conditioned air
100% outdoor air systems : only outdoor air to multiple ventilation zones, cannot have recirculating systems within various ventilated zones
Multiple-zone recirculating system : mixed outdoor air + recirculating air to various ventilated zones (VAV system or rooftop system)