air quality
BLDG 475/6751 Indoor Air Quality (& Ventilation) Department of Building, Civil & Environmental Engineering Faculty of Engineering and Computer Science Concordia University Assignment #2 1. The samples of two different carpets were tested for VOC emissions in 20m 3 environmental chamber made of stainless steel. Dynamic tests were conducted under the following conditions: - Temperature: 23 oC - Relative humidity: 50% - Air exchange rate: 1 hr ‐1 - Loading factor: 0.44 m 2/m 3 The following test results (chamber concentrations in ug/m 3) for 4‐phenylcyclohexene (4‐ PCH) were obtained. Time [hr] Carpet A Carpet B 3.0 42.8 48.5 6.0 44.0 44.7 12.0 40.4 36.5 24.0 37.0 34.8 48.0 34.3 29.8 72.0 31.2 29.4 96.0 30.8 25.2 120.0 28.6 23.8 144.0 26.6 21.6 168.0 26.8 20.9 a) Using the mass balance equation, determine the emission rates of each carpet (as a function of time) b) After one‐week of airing out, each carpet was installed wall‐to‐wall in an identical open‐ plan office with constant volume ventilation system. The area of the office is 2000 ft2 (185.8 m 2) and the number of expected occupants is 10. Assuming the carpets are the only source of 4‐PCH, estimate the 4‐PCH concentrations of both offices in ppm or ppb unit. Consider two ventilation cases: one complying ASHRAE Standard 62.1 Ventilation Rate Procedure (VRP) and the other is 30% more than VRP to comply LEED v.4 BD&C EQ credit “Enhanced Indoor Air Quality Strategies”. 2. Evaluate the effect of “flush‐out” option of LEED v4 BD&C EQ credit “Indoor Air Quality Assessment” Option 1‐Flush Out using IA‐Quest for an office space: Size: 15 m × 20 m × 3.2 m Number of occupants: 25 Occupancy hours: 08:00 – 18:00, 7 days a week Outdoor air ventilation rate Flush out period: 500 liter/sec After occupancy: minimum ventilation rate set by ASHRAE Standard 62.1 VRP Window & door area : 40 m 2 Office finishing materials Wall‐to‐wall carpet with adhesive on concrete slab (Crp7a) Latex paint (PT7) on plain gypsum board (GB1) for all wall finishing except window & door area Cellulose acoustical ceiling tiles (ACT3) Considered contaminants: toluene and TVOC Toluene: initial room concentration 0.2 mg/m 3; outdoor air concentration 0.01 mg/m 3 TVOC: initial room concentration 2.0 mg/m 3; outdoor air concentration 0.1 mg/ 3 Simulate the following three cases for 60 days and (a) Draw two figures (one for toluene and the other for TVOC) comparing the concentration profiles (Concentration vs. time curves) of three cases. (b) Determine the highest & the lowest TVOC concentrations during occupancy for each case on the day 30, 40, 50 & 60. Compare with toluene and TVOC concentration limits set in LEED v4 BD&C EQ Credit “Indoor Air Quality Assessment” Option 2‐Air Testing. (c) Examine the simulation results of three cases and discuss the limitations of IA‐Quest. Case 1: Flush‐out path 1 (a) The space is ventilated constantly at 500 liter/sec of outdoor air for flush‐out until the total 4,267,140 liters of outdoor air per square meter of gross floor area is delivered (b) After the flush‐out period, the building is occupied and regular ventilation schedule is applied: o 07:00 – 18:00 period with the ventilation rate equals to the minimum requirement of ASHRAE 62.1 VRP o Overnight the ventilation system is turned off. Case 2: Flush‐out path 2 (a) The space is ventilated constantly at 500 liter/s of outdoor air for flush‐out before occupancy until 1,066,260 liters of outdoor air per square meter of gross floor area is delivered. (b) Then, the building is occupied, and the flush‐out is continued following the Path 2 until total (including pre‐occupancy flush‐out) 4,267,140 liters of outdoor air per square meter of gross floor area is delivered: o 05:00 – 18:00 period with 500 liter/sec o Overnight the ventilation system is turned off. (c) Once the flush‐out is finished, the regular ventilation schedule is applied: o 07:00 – 18:00 period with the ventilation rate equals to the minimum requirement of ASHRAE 62.1 VRP o Overnight the ventilation system is turned off. Case 3: No flush‐out The building is ventilated using the regular ventilation schedule: o 07:00 – 18:00 period with the ventilation rate equals to the minimum requirement of ASHRAE 62.1 VRP o Overnight the ventilation system is turned off.
