Time-Based Scheduling of Residential Ventilation

Transcription

1 Time-Based Scheduling of Residential Ventilation by Armin Rudd USDOE Building America Program for EEBA Conference 2000 Building for Peak Performance Denver, Colorado 26 October 2000

2 Climate Specific Design Solutions buildingscience.com October 2000 Building Science Consortium

3 Purposes of ventilation 1. Point-source ventilation - Remove Pollutants exhaust fans: kitchen, bath, laundry 2. Whole-building ventilation - Dilute Pollutants supply, exhaust, or balanced fans distributing to all rooms

4 Time Basis of ventilation operation 1. Continuous, or constant operation usually smaller fans: supply, exhaust, HRV/ERV 2. Intermittent operation usually larger fan/blower: central air handler

5 Constant Operation Sizing cfm per person (use bedroom count plus 1 as estimate) cfm per person + offgasing ventilation cfm per person + offgasing + excess capacity Timing no timing or scheduling controls needed, except: an ON/OFF switch for vacations or unusual circumstances a bump-up control to get excess capacity for a time

6 Intermittent Operation Sizing constant flow divided by duty cycle fraction constant flow reduced by low background infiltration amount when blower is not on, all divided by duty cycle fraction Q& cfan = ( & I Qcont) ( V ( 1 f )) 60 f

7 Intermittent Operation where, on f = = t on t + t off t t on total and, t on f ( toff ) = 1 f and, t off = ( 1 f f ) t on

8 Intermittent Operation Sizing, cont. have fixed outside air flow to work with and back-calculate the duty cycle needed f = Q& Q& co in IV 60 IV 60

9 Timing Intermittent Operation basic equation: t t total = on + choose which terms you want to fix (selected by design) and which ones you want to be variable (user selected) t off t off t on t total calculated variable fixed fixed fixed calculated variable variable calculated

10 Builder Town & Country Homes Subdivision Centennial Crossing Location Climate Vernon Hills, Illinois cold Homes Started or Completed 189 of 191 Ventilation system Central-fan-integrated supply with fan recycling - 6 insulated OA duct to AHU return, with balancing damper - 7% outside air fraction, minimum 33% duty cycle - filtration by AHU filter - no complaints after three years October 2000 Building Science Consortium

11 Central-fan-integrated supply ventilation Interior closet or basement configuration Thermostat Humidistat (optional) Control Wiring Terminals Supply Air To Interior Space Return Air From Interior Space Exterior Wall Wall Cap with Insect Screen AirCycler TM Control buildingscience.com Heating/ Humidifying Apparatus 6" Insulated Outside Air Duct Ventilation Air Intake (locate away from pollutant sources) Air Distribution Fan Air Handler Unit Cooling/ Dehumidifying Apparatus Field measurement of outside air duct pressure, used to set balancing damper position Filter/Air Cleaner Register box adapted with slide-in filter Balancing Damper October 2000 Building Science Consortium

12 Central-fan-integrated supply ventilation Unvented-cathedralized attic configuration Gable End Wall AirCycler TM Control Supply Air Heating Coil Cooling Coil Main Return Duct buildingscience.com Wall Cap Extended Collar Gypsum Ceiling Central Return Box Return Grille and Filter Metal Tabs to hold filter Outside Air Filter cut from blank Outside Air Duct 5" Insulated Flex-duct Balancing Damper October 2000 Building Science Consortium

13 Monitored Runtime Data Centennial Crossing, Lot 22 Fan Recycling Cool ON Heat ON Vent ON Cost (%) (%) (%) ($) Apr (27-30) May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar (1-9) Notes: Fan recycling control set for 25 min OFF, 6 min ON (19% duty cycle)

14 Monitored Runtime Data Centennial Crossing, Lot 176 Fan Recycling Cool ON Heat ON Vent ON Cost (%) (%) (%) ($) Aug Sep Oct Nov Dec Jan Feb Notes: Fan recycling control set for 20 min OFF, 8 min ON (29% duty cycle)

15 Monitored Runtime Data Centennial Crossing, Lot 179 Fan Recycling Cool ON Heat ON Vent ON Cost (%) (%) (%) ($) Oct Nov Dec Jan Feb Mar (1-8) Notes: Fan recycling control set for 20 OFF 10 ON (33% duty cycle)

16 Lot 6 Arbor View Indoor temperature variation from the house average 6 Temperature Variation (F) max min avg -6 Return Storage Mbed Hall Great Dining Bed 2