NC-2009 IEQp1: Minimum indoor air quality performance Required

For projects that do not qualify with the requirements of the Ventilation Rate Procedure, or ASHRAE 62.1 Section 5.1, or CIBSE Applications Manual 10, and are pursuing an engineered ventilation system (e.g. a combination of natural ventilation with mechanical exhaust, or some other means of assisting the outside airflow through the openings and circulating it through the occupiable space), the following expectations apply:Compliance when the local ventilation code governing the project is ASHRAE 62.1-2007 (or 2004 for LEED-v2 projects): We understand that many local jurisdictions would not be willing to provide confirmation that your engineered natural ventilation approach meets the intent of ASHRAE 62.1-2007. Therefore, in locations where ASHRAE 62.1-2007 is required for local ventilation code compliance, it would be sufficient to document that the plans and specifications that use the engineered natural ventilation approach have been approved by the local code authority in order to show compliance with EQ Prerequisite 1. The documentation required for EQp1 would include confirmation that all of the mandatory requirements of ASHRAE 62.1 have been met, a narrative describing the engineered ventilation modeling approach, evidence documenting that the plans have been approved by the local code authority, and some form of evidence that ASHRAE 62.1-2007 (or a later version of ASHRAE 62.1) is required for local building code compliance.Compliance when the local ventilation code governing the project can be documented to be at least as stringent as ASHRAE 62.1-2007 (or 2004 for LEED-v2 projects):If the local code requirements relative to ventilation are governed by an alternate code (any code other than ASHRAE 62.1-2007 (2004 for LEED-v2) or a later version of ASHRAE 62.1), then the project team must provide evidence that this alternate code is at least as stringent than ASHRAE 62.1-2007 (2004 for LEED-NCv2) in its entirety. If this documentation could be provided, then the approval of the local code authority would be sufficient to document compliance with the prerequisite requirements. Using this methodology, the documentation required for EQp1 would include documentation showing that the alternate code is at least as stringent than ASHRAE 62.1-2007 (2004 for LEED-v2) in its entirety, confirmation that all of the mandatory requirements of the alternate code have been met, a narrative describing the engineered ventilation modeling approach, and evidence documenting that the plans have been approved by the local code authority. Compliance when the local ventilation code governing the project cannot be documented to be at least as stringent as ASHRAE 62.1-2007: If the documentation described above cannot be provided, then, for purposes of LEED Certification, USGBC/GBCI would serve as the Authority Having Jurisdiction [since the local code authority does not have jurisdiction over ASHRAE 62.1-2007 (2004 for LEED-v2) or a ventilation standard of equivalent stringency]. In this case, the project team would be required to submit documentation showing that the intent of ASHRAE 62.1-2007 (2004 for LEED-v2) has been met with the project\'s engineered natural ventilation system. This documentation must clearly identify how the natural ventilation requirements stipulated in ASHRAE 62.1-2007 (2004 for LEED-v2) Section 5.1 have not been met (e.g. smaller operable window area, larger distance from operable windows or openings, etc.). The documentation must also clearly identify how the ventilation design has been engineered to meet the intent of ASHRAE 62.1 where the requirements of Section 5.1 have not been met. For example, if the distance from windows or openings is more than 25 feet, is there an exhaust air fan located at the furthest distance from the windows that is inducing the outdoor air to flow through the space; is that exhaust fan flow equivalent to the outside airflow that would be required for the space if the Ventilation Rate Procedure were used? If the window area is less than 4% of the floor area, is the space designed with cross-ventilation to ensure adequate airflow? Drawings and some calculations or air flow analyses will be required in addition to the narrative describing the engineered ventilation approach to justify this approach. For projects that have not yet entered the review process, it is highly recommended that this be provided in a project-specific credit interpretation request in order to achieve prior approval of the engineered natural ventilation approach rather than waiting until the system has been fully designed to pursue approval of this method.Below are some specific examples of the types of documentation that would be required if using this compliance approach; but these examples are not intended to apply to every possible engineered ventilation solution:For example, in high rise residential, the team must identify any occupiable spaces (excluding coat closets and entry vestibules) in the residential units that are more than 25 feet away from the operable windows, that are interior spaces with unobstructed free area from adjacent rooms that is less than 8% of the area of the interior room, or that have operable window openings that totals less than 4% of the total naturally ventilated floor area. A narrative and/or calculations should be provided explaining how mechanical ventilation or a combination of mechanical ventilation and natural ventilation are used to meet the ventilation requirements for those spaces. For spaces or portions of spaces that are ventilated using mechanical ventilation or a combination of mechanical and natural ventilation, the documentation must show compliance with the ventilation rates indicated in Table 6-1 of ASHRAE 62.1-2007 (2004 for LEED-v2) and the Ventilation Rate Procedure calculations indicated in Section 6.2, using appropriate values for zone air distribution effectiveness (Ez.)For high-rise residential projects attempting to show compliance for EQp1 using positively pressurized corridors that are provided with excess outdoor air [above ASHRAE 62.1-2007 (2004 for LEED-v2) minimum requirements] that is to be transferred into each living unit either via undercuts in the entry doors, transfer air grilles, or some other means, the project team must document that all mechanically ventilated spaces will meet the minimum ventilation requirements of ASHRAE 62.1-2007 (2004 for LEED-v2) Section 6.2. For projects utilizing bathroom or other exhaust to negatively pressurize the unit to draw in excess ventilation air from the corridors, if the primary makeup air source for the unit exhaust is designed to be provided through the apartment entrance/vestibule, the project team should sufficiently demonstrate that the makeup air is outdoor air and not relief air (or previously "used" outside air) from other occupied spaces in the building and that the exhaust operates continuously. Additionally, note that for the case of makeup air provided from the apartment entrance, the makeup air may substantially short-circuit the space requiring mechanical ventilation depending on the location of the air entry point and the exhaust grilles, and therefore an appropriate air distribution effectiveness (Table 6-2) must be considered (see example 6-H from the ASHRAE 62.1-2007 User\'s Manual - p. 6-20, where a zone air distribution effectiveness of 0.5 is utilized.)