Fading grid on green Commercial Building Ventilation and Indoor Environmental Quality
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Indoor VOC's

VOC Concentrations and Emissions in New Houses

Study to characterize VOC concentrations and emissions in new manufactured and site-built houses
Indoor sources of VOCs are a determinant of air quality in houses. Many materials used to construct and finish the interiors of new houses emit formaldehyde and other VOCs. Air contamination resulting from these emissions potentially can cause health effects and discomfort among occupants. Ventilation is the other main determinant of air quality in houses. Ventilation serves as the primary mechanism for the removal of gaseous contaminants generated indoors. The trend in new house construction is to make house envelopes tighter with respect to air leakage to improve energy performance. Consequently, ventilation rates in new houses without some form of supplemental ventilation can be low with a potential for degraded air quality.

There was a general lack of contemporary data on concentrations of VOCs in new houses being constructed in the U.S. It also was suspected that changes in the products and materials used in new house construction over the last decade have impacted VOC concentrations. Thus, in 1997 and 1998 the IED in collaboration with the Florida Solar Energy Center (FSEC) conducted a study to characterize the concentrations and emissions of VOCs in selected new manufactured and site-built houses (Hodgson et al., 2000). The primary objectives were to compare these two housing types and to identify sources of VOCs of concern.

Four new manufactured houses in one project and 7 new site-built houses in three projects were selected for study. The houses were located in eastern and southeastern states in mixed-humid and hot-humid climates. They were finished and operational, but unoccupied. The manufactured houses were decorated as sales models. The houses are described in Table 6 and Table 7.

Table 6 Descriptions of the 4 new manufactured study houses. All houses were produced at a single facility in Florida.

  Manufactured House I.D.
Parameter M1 M2 M3 M4

No. bedrooms/bathrooms 2/2 4/2 3/2 3/2
Floor area, m2 112 169 141 131
Volume, m3 273 412 344 320
HVAC system Heat pump Heat pump Heat pump Heat pump
Supplemental ventilation Nonea Fan re-cycleb None None
Carpeted floor area, % 64 76 67 73
Sheet vinyl floor area, % 0 17 21 16
Ceramic tile floor area, % 25 0 0 0
Low-VOC paint, Yes/No No Yes No No
Low emitting carpet, Yes/No No Yes No Yes

a No supplemental mechanical ventilation other than switched exhaust fan in living area

b Ducted outdoor air inlet and automatic fan re-cycle device installed on HVAC system
 

Table 7 Descriptions of the 7 new site-built study houses. The houses were located in three projects.

  Site-Built House I.D.
  Project A Project B Project C
Parameter A B1 B2 B3 C1 C2 C3

Completion date (mo/yr) 12/97 2/98 2/98 2/98 8/98 8/98 8/98
Sampling date (mo/yr) 12/97 4/98 4/98 4/98 9/98 9/98 9/98
No. floors 2 1 1 1 1 1 1
No. bedrooms/ bathrooms 3/1 3/1.5 3/1.5 3/1.5 3/2 3/2 3/2
Floor area, m2 111 97 92 90 110 110 110
Volume, m3 272 237 224 220 286 286 286
HVAC system Heat pump Heat pump Heat pump Heat pump Heat pump Heat pump Heat pump
Supplemental ventilation HRVa Noneb None None None None Fan re-cyclec
ASHRAE vent. rated, h-1 0.37 0.43 0.46 0.46 0.36 0.36 0.36
Exterior wall type Frame Frame ICFe ICF Frame Block Insul. Blockf
Carpeted floor area, % 70 80 80 80 84 84 84
Sheet vinyl floor area, % 30 20 20 20 16 12 16

a HRV = Balanced heat-recovery ventilation system

b No supplemental mechanical ventilation other than switched bathroom exhaust fan

c Ducted outdoor air inlet and automatic fan-recycle device installed on HVAC system

d ASRAE Standard 62 recommended ventilation rate for four occupants (ASHRAE, 1989)

e ICF = Insulating concrete form of expanded polystyrene with concrete core

f Insulated concrete block

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