Cold Climate Exhaust Ventilation Research in High Performance Homes

Residential Building Energy Efficiency Meeting 2010July 20, 2010

Dianne Griffiths, Steven Winter Associates, Inc.Consortium for Advanced Residential Buildings

Steven Winter Associates, Inc.

Ventilation ResearchSide-by-side comparison of three ventilation strategies in identical ENERGY STAR homes.• Energy Recovery Ventilation• Air Cycler Supply Ventilation• Exhaust-Only VentilationAll commissioned to deliver 60 CFM continuously (equivalent, per ASHRAE 62.2).

Steven Winter Associates, Inc.

Evaluating DistributionHouse 1: ERV

CO2 Distribution

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11/9/04 0:00 11/9/0412:00

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Date & Time

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bon

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xide

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n (p

pm) Outdoors

Living RoomMaster BRSecond BR

Steven Winter Associates, Inc.

Carbon Dioxide ConcentrationsWinter 2004-2005

CO2 Concentrations

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30%

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CO2 Concentration [ppm]

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ent o

f Rea

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1 - ERV2 - Air Cycler3 - Exhaust Only

Steven Winter Associates, Inc.

‘What If’ - Efficient Air Handlers(250 Watts)

Strategy ElectricitykWh/yr

GasTherms/Yr

Total Ventilation

CostERV +Air Handler

1899 -9 $184

Air Cycler 1304 54 $165Exhaust Only 263 76 $76

ERV, No Air Handler 595 13 $68

Steven Winter Associates, Inc.

RDI Prototype HomeColrain, MA

Two Panasonic WhisperGreen fans running continuously at 40 CFM, 6 Watts.

Steven Winter Associates, Inc.

NREL Tracer Gas Results

Steven Winter Associates, Inc.

RDI’s Wisdom Way Solar Village

Steven Winter Associates, Inc.

Heating System

• Design Loads10,000 – 12,000 Btu/h

• Room Heaters:– Lo: 10,200 Btu/hr – Hi: 16,000 Btu/hr– 83% AFUE– Sealed Combustion

Steven Winter Associates, Inc.

HVAC System – First Floor

Steven Winter Associates, Inc.

HVAC System – Second Floor

Steven Winter Associates, Inc.

Tracer Gas Testing

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Case 4 Case 2

RAO

A, h

r-1

Doors Open

living room

kitchen

SW BR

SE BR

NE BR

bath

Steven Winter Associates, Inc.

Tracer Gas Testing

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0.35

0.40

Case 4 Case 2

RAO

A, h

r-1

Doors Open Doors Closed(Fan OFF)

living room

kitchen

SW BR

SE BR

NE BR

bath

Steven Winter Associates, Inc.

Tracer Gas Testing

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0.05

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Case 4 Case 2 Case 1

RAO

A, h

r-1 living room

kitchen

SW BR

SE BR

NE BR

bath

Doors Open Doors Closed(Fan OFF)

Doors Closed(Fan ON)

Steven Winter Associates, Inc.

Comfort Tests & Monitoring

• Chief concern is temperature in upstairs bedrooms without direct conditioning;

• Short-term testing with NREL in Feb 2009 (when tracer gas testing done);

• Temperature monitoring of 4 occupied homes during winter of 2009-2010;

• Utility bills reviewed.

Steven Winter Associates, Inc.

Heating Comments• No comfort complaints from occupants of 4

monitored homes;• Heating system savings ($4,000 - $5,000)

allowed for added envelope costs ($7,000 -$10,000);

• Very little or no use of supplemental heaters in bedrooms;

• Gas space heating costs ≈ $200 - $400;• Design loads are comparable to normal

internal gains.

Steven Winter Associates, Inc.

Ventilation Gaps

• When and how much distribution/mixing is really necessary?

• HVAC for smaller loads, lower air flows• Filtration• Implications of maintenance (or lack thereof)• Role for air inlets or trickle vents?• Wider understanding of when and where

exhaust-only ventilation is (and is not) appropriate.