NSF Standard(S) Impacted:Section 4.3, Appendix a (Informative) of the Template for The

NSF Standard(s) Impacted:Section 4.3, Appendix A (informative) of the Template for the Draft Standard of NSF/UL 440

Issue Statement:

Indoor air quality (IAQ) concentration modeling is needed in material emission testing and evaluation standard in order to link the measured VOC emission rates to estimated airborne concentrations that are relevant to potential indoor inhalation exposures of building occupants.

Because of the diverse opinions within the Environment & Product work group on the scenario(s) to be used for IAQ concentration modeling, a multiple-model and a single-model sub-task group were formed separately. Both groups have been asked to each propose an initial document that can help the joint committee (JC) to determine whether the multiple or single model approach should be used as the basis for further standard development.

The Multiple-Model Sub-Task Group proposes the continued use of the multiple scenarios approach as used in the CDPH/EHLB Standard Method (SM) V1.1 (Section 4.3 and Appendix A in the template for the draft standard of NSF/UL 440). We believe this approach, with a limited number of application scenarios, better represents built environments, while retaining simplicity. Maintaining the continuity of the multiple scenarios also lends a practical path to facilitate market transition to the new standard and adaptation to evolving product types and scenarios.

Background:

The background on modeling scenarios (role, assumptions, equations, and key model parameters), the comparisons of exposure models currently available in various emission testing standards, and the history andmarket influence of the current CDPH SM (basis of the draft standard of NSF/UL 440) have all been discussed in details in the previous JC meeting (see supplemental materials). A brief summary is restated below:

Science behind using multiple scenarios

In material emission testing and evaluation, the first step is always to place a representative, small-scale sample of a newly manufactured building interior product into an environmental chamber at typical indoor conditions, and measure the area-specific emission rate, termed emission factor (EF) in units of µg/h•m2, at specified time points for each emitted VOC. Next, defined building modeling scenario(s) are used to convert measured VOC EFs into estimated indoor airborne VOC concentrations in order to interpret these measured results and link them to guidelines for occupant inhalation exposures. Test results for a product sample are deemed compliant with VOC emission requirements if the projected concentrations do not exceed the allowable limits which are set based on these exposure guidelines.

Regardless of single vs. multiple scenarios, the modeling is based on single-zone mass balance assuming constant VOC emission and building/houseair change rates, zero outdoor VOC concentrations, uniform indoor air concentrations, and no net losses of a VOC from air due to effects such as filtration, sorption on surfaces or chemical reactions. Under these assumptions, the indoor VOC concentration (CS in µg/m3) is estimated from the measured VOC EF (EFA in µg/h•m2), the area of material installed (Amin m2) in the building interior, and the total outdoor airflow rate (Qin m3/h):

CS= EFA x Am / Q = EFA / qA (1)

In Equation (1), qA (in m/h) is the area-specific airflow rate and can be expressed as:

qA= Q / Am = (λ x V) /Am = λ /(Am / V) = λ/ Lm (2)

where λ is the outdoor air change rate (Q/V) in h-1, V is the building volume in m3,and Lm is the product loading ratio (Am/V) in m2/m3.

Under ideal circumstances, a building product tested for VOC emissions should be labeled with numerical emission factors, so that its expected impacts on indoor VOC concentrations could be calculated for specific building projects using Equations (1) & (2) or more complex indoor air quality modeling tools. However, the desire for easy implementation and the competitive market forces among product manufacturers have motivated the use of simplified exposure models and the development of pass/fail systems for judging the acceptability of product’s potential IAQ impacts in VOC emission standards. The difference between single vs. multiple scenarios then focuses on how to define the area-specific airflow rate for different product types and application environments.

As defined in Equation (2), the area-specific airflow rate is the ratio of the outdoor air change rate to the product loading ratio. For different application environments, the design requirements and representative outdoor air change rates may be different. For example, a single-family house built with high air-tightness can have much lower outdoor air change rate compared to a mechanically ventilated office. The application environment may also affect the product loading ratio due to different space functionality and lay out. For example, the overall loading ratio for thermal insulation may be substantially higher in a single-family house than in an office. Because of the diversity of product types and their application conditions in buildings, we think scientifically it is worthy to take the efforts to define a limited number of application scenarios tobetter represent built environments yet still simple for practical use.

Market needs behind using multiple scenarios

The CDPHSM V1.1 (also known as Section 01350) has been widely adopted by many certification programs and product standards, and has been cited as a preferred procedure for testing and evaluating building products for compliance with VOC emission requirements in many green building rating systems and codes (see Figures 1a- 1d below). Therefore, keeping multiple scenarios, which is the approach used in the CDPH SM, helps to maintain the continuity and facilitate market transition.

Figure 1aFigure 1b

Figure 1c Figure 1d

Recommendation:

A template for the draft standard of NSF/UL 440 was issued by NSF on Feb 11, 2014. Section 4.3 and Appendix A of this document already contain widely-used office and classroom scenarios and a preliminary residential scenario. Given the main purpose of this issue paper, we propose:

(1) keeping all current contents of Section 4.3,

(2) taking the content of Appendix A as a new subsection (Section 4.3.7) in Section 4.3, and

(3) deleting Appendix A.

At the end of this Section the applicable Sections of “CDPH-IAQ_NSF_UL 440 Template Standard 021114” are shown with changes as described in (1) – (3) above.

As for the furniture testing and evaluation, we recommend the continued direct reference to thescience-based and well-recognized ANSI/BIFMA standards.

This proposal will be used as the starting document. The final language and modeling scenario parameters will be developed by the Environment & Product work group and recommended to the JC for adoption by the standard.For example, this subgroup is collecting information to evaluate the possible inclusion of a new Healthcare Scenario and the possible inclusion of requirements for wet-applied products with small surface areas that are not explicitly specified within the current template of the NSF/UL 440 draft standard. Several other details to be discussed are mentioned in the footnotes to Table 4-7. These are the possible apportionment of residential floor surface area by floor covering type and the possible inclusion of residential cabinetry. Other details that have been mentioned or discussed in work group conference calls include possible apportionment of thermal insulation by building area (e.g., ceiling and wall cavity) and possible use of an attenuation factor for insulation to account for the fact that insulation is not directly exposed to indoor air. If the joint committee determines to select the multiple model approach, we will move forward to complete these evaluations and suggest final language accordingly. We will also make other necessary revisions/developments based on the comments/suggestions from the JC and from the members of Environment & Product work group. We expect such revisions to be more in line with incremental improvements to the multiple models.

Affected Sections of “CDPH-IAQ_NSF_UL 440 Template Standard 021114” with changes as discussed in the Recommendation portion of this Issue Paper.

4.3IAQConcentrationModeling

4.3.1Principle:ThepurposeofIAQconcentrationmodelingistoconvertthemeasuredVOCemissionratesintoestimatedairborneconcentrationsthatarerelevanttopotentialindoorinhalationexposuresofbuildingoccupants.Thecalculationisaccomplishedusingasteady-statemass-balancemodelwithseveralsimplifyingassumptionsdescribedinSection3.10.ThecalculationrequiresinputsfortheemissionfactorofaVOCemitted byaproductandtheflowrateofoutdoorairperunitamountofproduct.

4.3.2Area-specificairflowrate:ForaproductwithagivenVOCemissionfactor,therelationshipthatdetermines,toafirst-orderapproximation,thegas-phaseVOCconcentrationinatestchamberandinabuiltenvironmentistheflowrateofoutdoorventilationairperunitareaofproduct.Thisparameteristermedthearea-specificairflowrateandhasunitsofm3h-1m-2(mh-1).Itisalsoobtainedfromtheratiooftheairchangeratetotheloadingfactor(sometimesdescribedasN/L)withthesameunits.

4.3.3Standardizedscenarios:Typicalproductcategories(e.g.,floorcoverings,wallcoverings,paint,acousticalceilings,etc.)arespecifiedwithrespecttotheirloadingineachbuildingenvironment(i.e.,schoolclassroomsandprivateofficesinpublic/commercialbuildings)andtheflowrateofoutdoorair.

4.3.4Schoolclassroomscenario:Theschoolclassroommodelisbasedonthedimensionsofatypical re-locatableclassroom;theclassroomsizealsoisgenerallyrepresentativeofsite-builtclassrooms forK-12schools(Jenkins,PhillipsandWaldman,2004).Theparametersthatdefinethestandard schoolclassroomtobeusedwiththismethodarelistedin Table4-2.ThesurfaceareasofmajorproductcategoriesandunitquantitiesofpupildesksandseatingintheschoolclassroomarepresentedinTable4-3alongwiththecalculatedcorrespondentarea-specificairflowratesorunit-specificairflowrates.

Table4-1 – TargetCRELVOCsandtheirmaximumallowableconcentrations

Table4-2 – Definitionofstandardschoolclassroom

Table4-3 – ProductquantitiesandspecificairflowratestobeusedforestimationofVOCconcentrationsinstandardschoolclassroom

4.3.5Privateofficescenario:Theprivateofficemodelisbasedonassumeddimensionsofanenclosedofficeinapublic/commercialbuildingthatisoccupiedbyasingleindividual.TheparametersthatdefinethestandardprivateofficetobeusedwiththismethodarelistedinTable4-4.ThesurfaceareasofmajorproductcategoriesarepresentedinTable4-5alongwiththecalculatedcorrespondentarea-specificairflowrates.Thisprivateofficescenarioappliestobuildingmaterialsandproductsotherthanofficefurnitureorseatingunits.PrivateofficeworkstationsarenotaddressedwithinthecurrentscopeofthisStandardMethod.Forofficeseating,refertoSection7.

Table4-4 – Definitionofstandardprivateoffice

Table4-5 – ProductquantitiesandspecificairflowratestobeusedforestimationofVOCconcentrationsinastandardprivateoffice

4.3.6Modelingparametersforproductsnotspecificallyaddressedindatatables:Thereareanumberofproductsforwhichdataonstandardapplicationsarenotreadilyavailable;manyadhesives,caulks,sealants,andwallboardfinishingproductsfallintothiscategory.Fortheseproducts,theloadingshallbedeterminedbasedon(a)thesurfaceareaofthesystem(i.e.,ceiling,wall,orfloor)intheselectedstandardenvironment(i.e.,classroom,privateoffice,orsingle-familyresidence),wheretheproductisapplied,and (b)theproduct’sstandardapplicationspecifications.Forexample,flooringadhesiveshallbemodeledusingtheentirefloorareaofthespaceandthemanufacturer’spublishedapplicationrateforthatadhesive(e.g.,gm-2).Parametersusedtoestablishtheloadingshallbemadepartofthetestreportrecordandmadeavailablethroughthecertificationreportifthemodelingparametersaredefinedbyacertification/verificationorganization(Section6.1.4).

(Section 4.3.7 are proposed new normative requirements, based on existing informative Appendix A)

4.3.7 Single-family residence scenario: Lack of residential scenario(s) is a major gap in the application of Standard Practice (2004). A preliminary new single-family residence model has been developed. It The single-family residence scenario isbasedontheassumeddimensionsofamediansizenewdetachedsingle-familyhome.Theparametersthatdefinethestandardnew single-familyresidencearelistedinTableA-14-6.Thesurfaceareasofmajorproductcategoriesandunitquantitiesofothercomponentsinthestandardnew-singlefamilyresidencearegiveninTableA-24-7alongwiththecalculatedcorrespondentarea-specificairflowratesorunit-specificairflowrates.

TableA-14-6 – Definition of new single-family residence

(Delete Appendix A as it would now be included in the normative requirements.)

AppendixA[1]

(informative)

New single-family residence scenario

Lackofresidentialscenario(s)isamajorgapintheapplicationofStandardPractice(2004).Apreliminarynewsingle-familyresidencemodelhasbeendeveloped.Itisbasedontheassumeddimensionsofamediansizenewdetachedsingle-familyhome.Theparametersthatdefinethestandardnewsingle-familyresidencearelistedinTableB-1.Thesurfaceareasofmajorproductcategoriesandunitquantitiesofothercomponentsinthestandardnew-singlefamilyresidencearegiveninTableB-2alongwiththecalculatedcorrespondentarea-specificairflowratesorunit-specificairflowrates.

TableA-1 – Definition of new single-family residence

1Item No.______

(For NSF International internal use)

03/2013

TableA-2 – ProductquantitiesandspecificairflowratestobeusedforestimationofVOCconcentrationsinstandardnewsingle-familyresidence.

B2

TableA-24-7 – ProductquantitiesandspecificairflowratestobeusedforestimationofVOCconcentrationsinstandardnewsingle-familyresidence.

Supplementary Materials (photographs, diagrams, reports, etc.):

The presentations givenat last JC meeting,including (1) Introduction of CDPH SM, and (2) Progress report of multiple-model work group, are attached to provide more background and history on this issue,. The template for the draft standard of NSF/UL 440as issued in Feb, 2014is also attached.

I hereby grant NSF International the non-exclusive, royalty free rights, including non-exclusive, royalty free rights in copyright; in this item and I understand that I acquire no rights in any publication of NSF International in which this item in this or another similar or analogous form is used.

Signature*: Wenhao Chen, Ph. D. (on behalf of the Multiple Model Subtask Group)Company: California Department of Public Health

Telephone Number: (510) 620-2868

E-mail:

Submission Date:October 7, 2014

Signature*: Nicole Munoz (on behalf of the Multiple Model Subtask Group)

Company: SCS Global Services

Telephone Number: (510) 452-8031

E-mail:

Submission Date:October 7, 2014

Please submit to:Jessica Evans () or Tim Corder ().

*Type written name will suffice as signature

1Item No.______

(For NSF International internal use)

03/2013

[1]ThisisaninformativeappendixandnotpartoftherequiredportionofthisStandardMethod.ItistheintentoftheCDPH-IAQtofurtherreviewanddeveloptheSingleFamilyResidenceScenarioforinclusioninfinalforminVersion2.0oftheStandardMethod.