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IEQ c2: Increased Ventilation


To provide additional outdoor air ventilation to improve indoor air quality (IAQ) and promote occupant comfort, well-being and productivity.


Case 1. Mechanically ventilated spaces

Increase breathing zone outdoor air ventilation rates to all occupied spaces by at least 30% above the minimum rates required by ASHRAE Standard 62.1-2007 (with errata but without addenda) as determined by IEQ

Prerequisite 1: Minimum Indoor Air Quality Performance.

Case 2. Naturally ventilated spaces

Design natural ventilation systems for occupied spaces to meet the recommendations set forth in the Chartered

Institution of Building Services Engineers (CIBSE) Applications Manual 10: 2005, Natural Ventilation in Non-domestic Buildings.  Determine that natural ventilation is an effective strategy for the project by following the flow diagram process shown in Figure 2.8 of the CIBSE Applications Manual 10.



Option 1

Use diagrams and calculations to show that the design of the natural ventilation systems meets the recommendations set forth in the CIBSE Applications Manual 10: 2005, Natural Ventilation in Non-domestic Buildings, CIBSE AM 13 (Mixed Mode Ventilation), or natural ventilation/mixed mode ventilation related sections of the CIBSE Guide B2 (Ventilation and Air Conditioning).


Option 2

Use a macroscopic, multi-zone, analytic model to predict that room-by-room airflows will effectively naturally ventilate, defined as providing the minimum ventilation rates required by ASHRAE 62.1-2007 Chapter 6 (with errata but without addenda 1 ), for at least 90% of occupied spaces.


Potential technologies & Strategies


For mechanically ventilated spaces: Use heat recovery, where appropriate, to minimize the additional energy consumption associated with higher ventilation rates.

For naturally ventilated spaces, follow the 8 design steps described in the Carbon Trust Good Practice Guide 237:

  • Develop design requirements.

  • Plan airflow paths.

  • Identify building uses and features that might require special attention.

  • Determine ventilation requirements.

  • Estimate external driving pressures.

  • Select types of ventilation devices.

  • Size ventilation devices.

  • Analyze the design.

Use public domain software such as NIST’s CONTAM, Multi-zone Modeling Software, along with Loop DA, Natural Ventilation Sizing Tool, to analytically predict room-by-room airflows.


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