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TOUR OF NIST MANUFACTURED RESEARCH HOUSE. Andy Persily, Steve Nabinger, Steve Emmerich, Cindy Howard Reed Building and Fire Research Laboratory National Institute of Standards and Technology Michael Lubliner Washington State University October 2, 2002. SCHEDULE FOR MORNING. - PowerPoint PPT Presentation
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TOUR OF NIST MANUFACTURED RESEARCH HOUSE
Andy Persily, Steve Nabinger, Steve Emmerich, Cindy Howard Reed
Building and Fire Research LaboratoryNational Institute of Standards and Technology
Michael LublinerWashington State University
October 2, 2002
SCHEDULE FOR MORNING
• Background on NIST manufactured house ventilation and IAQ research
– NIST Modeling study for HUD
• Mike Lubliner on DOE/EPA/HUD activities
• Tour of research house
A MODELING STUDY OF VENTILATION IN MANUFACTURED HOUSES
Andrew K. Persily, Samuel R. MartinBuilding and Fire Research Laboratory
National Institute of Standards and TechnologyGaithersburg, Maryland USA
ASHRAE/BETEC/CIBSE/ORNL/DOE/NRCC Performance of Exterior Envelopes of Whole Buildings VIII
December 2001
Funded by US Dept of Housing and Urban Development
BACKGROUND
US manufactured homes built to HUD Manufactured Homes Construction and Safety Standards
MHCSS RequirementsMinimum air change rate of 0.35 h-1
Mechanical or passive system to provide 0.1 h-1
(assumes infiltration rate of 0.25 h-1)
Variety of systems being used to meet standardOutdoor air intake on forced-air furnace return
Whole house exhaust fan with or without inlet vents
STUDY QUESTIONS
Validity of 0.25 h-1 assumption for infiltration
Ventilation rates, air distribution and energy use of systems being used to meet the MHCSS standard:
Outdoor air inlet on furnace returnWhole house exhaust fan with passive inlet vents
Whole house exhaust fan without passive inlet vents
SIMULATION APPROACH
CONTAM multizone airflow model:Exterior envelope leakage, interior partitions, forced-
air distribution and duct leakage, exhaust fan operation, and outdoor weather
Steady-state airflow simulations for different systems
Annual simulations for different systems: Miami (hot/humid), Albany (cold/mixed), Seattle (temperate)
Albany: Forced-air intake controlled by heating & cooling demand
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
-20 -10 0 10 20 30 40 50
Indoor-outdoor temperature difference (°C)
Air Change Rate (h
-1)
SAMPLE RESULTS (Albany)
Simulation conditions Mean air change
rate (h-1)
% of hours < 0. 35 h-1
Effective air change rate (h-1)
Envelope leakage and scheduled exhaust fans
0.27 77 0.17
Forced-air inlet; operating on outside temperature
0.37 46 0.19
Forced-air inlet operating during occupancy
0.59 18 0.34
Passive inlets: whole house exhaust on limited schedule
0.41 42 0.24
Passive inlets: whole house exhaust on during occupancy
0.50 29 0.34
ENERGY CONSUMPTION (Albany)
Simulation conditionsAnnual Energy Use MJ (kWh)
Heating, Cooling and Fans
No “mechanical ventilation”; ductleakage and exhaust only
18459 (5128)
Forced-air inlet; operating on Tout 20140 (5595)
Forced-air inlet operating duringoccupancy
31339 (8706)
Passive inlets: whole house exhaustoperating on limited schedule
21217 (5894)
Passive inlets: whole house exhaustoperating during occupancy
24646 (6846)
Constant air change rate; 0.35 h-1 14970 (4159)
CONCLUSIONS0.25 h-1 assumption for infiltration
Ignores weather; < 0.25 h-1 for much of the year
Outdoor air inlet on furnace returnProvides sufficient ventilation and good distribution, but impact depends on operating strategy; potential
for both under- and over-ventilation
Whole house exhaust fan with passive inlet ventsSufficient ventilation and good distribution, but
depends on operation; potential for under- and over-ventilation; make more sense in tight buildings
RECOMMENDATIONS
Modify infiltration assumption in standard to account for weather-induced variation
Standards need to address operation of mechanical ventilation systems
“Optimize” by tightening ducts and building envelope, then assess systems
Verify findings through field studies
Investigate pollutant impacts of ventilation
NIST RESEARCH HOUSEDelivery and installation, January 2002
NIST RESEARCH HOUSE
Installation of instrumentation, Spring 2002
Initial testing
RESULTS TO DATE (preliminary)
•Airtightness–Whole building blower door: 9.1 h-1 at 50 Pa, ELA at 4 Pa = 103 in2
–Duct leakage: 225 cfm at 25 Pa
•Tracer gas measurements of air change rate–Forced-air fan off: 0.1 - 0.2 h-1 (summer)
–Forced-air fan on, intake closed: 0.4 - 0.5 h-1 (summer)
–Forced-air fan on, intake open: 0.4 - 0.6 h-1 (summer)
•Initial VOC concentrations and emissions
•Initial relative humidity levels and removal by AC
CONTAM MODELS OF HOUSECrawl space
CONTAM MODELS OF HOUSE
Living area
SYSTEM AIRFLOWS (preliminary)Measured and predicted with CONTAM
Measured(cfm)
Predicted(cfm)
Sum of supply registers 736 736Supply leak into crawl space -- 197Total flow through fan 942 933
Return grille 925 918
Outdoor air intake 16 16
EXHAUST AND INTAKE AIRFLOWS (preliminary)
Design and measured values
Required(cfm)
Measured(cfm)
Kitchen exhaust 100 47Bath exhaust #2 50 20Master bath exhaust 50 20Whole house exhaust 53 20
Outdoor air intake 53 16
INDOOR VOC LEVELS (preliminary)
503
400
450
500
550
600
650
700
750
800
08/09 00:00 08/10 00:00 08/11 00:00 08/12 00:00 08/13 00:00 08/14 00:00
Date & Time
Concentration (ug/m3)
0
10
20
30
40
50
60
70
80
Temperature (C)
TVOC Temp_IN Temp_OUT Temp_CRAWL
RESEARCH PLANS Complete initial characterization, fall ‘02 Air change rates under different operating modes
Fans off, infiltration only Forced-air operating on thermostat, with intake open/sealed Forced-air operating, bath & kitchen exhaust fans on schedule Forced-air operating, whole house exhaust, window vents open/sealed
Compare measured and predicted (CONTAM) air change rates
Characterization of humidity performance, water vapor storage in materials and furnishings
Performance of gaseous air cleaners VOC/formaldehyde emissions over time (LBNL)
LONGER TERM RESEARCH
Retrofit
First stage, could have been done at little cost
Address envelope and duct leakage
Second stage, more advanced and cost
Replace forced-air system
Efficient whole house exhaust Details studies of moisture: sources, transport and
ventilation Emissions from combustion appliances