BEST PRACTICE RECOMMENDATIONS - PHIUS · Intake and exhaust hoods min 6’ apart, above snow levels...

Second and Delaware, Kansas City, MO

BEST PRACTICE RECOMMENDATIONS

©2016 Passive House Institute US | PHIUS 1

OUTLINE

� VENTILATION & COMPONENT REQUIREMENTS UNDER PHIUS+

� COMPARISON TO OTHER VENTILATION STANDARDS:

� ASHRAE 62.2 2016 ERV/HRV� ASHRAE 62.2 2016 ERV/HRV

� IRC

� BSC Standard 01

� CONCLUSIONS & RECOMMENDATIONS

2©2016 Passive House Institute US | 2

LEARNING OBJECTIVES

� Understand the ventilation and system requirements for PHIUS+2015 certification as currently in place

� Understand components and layout requirements and best practices

� Understand how PHIUS+ ventilation system requirements differ from other ventilation requirements differ from other ventilation standards

� Understand tech committee to be working on issuing/confirming guidance on appropriate kitchen exhaust solution

3©2016 Passive House Institute US |

Definition &

Purpose

Controlled movement of air into

and out of a building, generally

using mechanical means,

through deliberately placed

holes in the building envelope

Provide the necessary

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Provide the necessary

fresh(supply) air and remove

the necessary stale (exhaust)

air to maintain high indoor air

quality (control temperature,

humidity, odors, carbon

dioxide, airborne contaminants,

etc.) inside the building

©2016 Passive House Institute US |

Contaminants in Indoor Air

Molds

Pollens

Pets

From Outdoors From Indoors

People

Dust

Radon

Mold/Bacteria

Formaldehydes

VOC/PM-2.5 &10

Soil gases CO2 + Humidity

5

CO


Methods for Improving Indoor Air Quality

Pets, harmful cleaners,

bathroom/kitchen moisture &

odors, airborne contaminants, off-

gassing building materials, etc.

1: Source Control

Bring in “fresh” outside air, exhaust

“stale” inside air

2: Ventilation

Clean the inside air

3: Filtration


Mechanical Ventilation Methods

•Neutral Pressure

•Air Inlet & Exhaust Controlled

Balanced

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Heat Recovery Ventilation Heating Loss is equal to

0.6-2.2 kBTU/ft²yr for cool moderate climate.

This is 13-46% of the PH Heating Limit (4.75 kBTU/ft²yr)

Controlled

•VERY Efficient w/ Heat Recovery

Balanced


Mechanical Ventilation Methods

•Depressurizes Building

•Draws Air in Randomly

•Poor Efficiency

•May Hurt Building Durability

Exhaust Only

Exhaust Only

•Pressurizes Building

•Forces Air Out Randomly

•Poor Efficiency

•May Hurt Building Durability

Supply OnlySupply Only

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Exhaust or Supply Only Ventilation Heating Loss is equal to

6.3-9.5 kBTU/ft²yr for Central Europe

This is 133-200% of the PH Heating Limit (4.75 kBTU/ft²yr)


Mechanical Ventilation Heat Recovery Efficiency

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s. www.PHIUS.ORG /Tools/Resources for:

1. HVI-Winter-Ratings-modified-for-PHIUS-modeling


Ventilation System ConceptFor Excellent Distribution

ALL Ventilation Through HRV/ERV

Air Extracted


Air Extracted from “Wet” Rooms

Supplied to Living/Sleeping Rooms

Ventilation Flow Criteria

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Extract Air:Extract Air:

• Kitchen – 35 cfm

• Bathrooms – 24 cfm

• ½ Bath – 12 cfm

Max Design

Airflow =

Greater of

Supply/

Extract

PH delivered ventilation exceeds ASHRAE 62.2, because PH sizes

ventilation systems to meet actual loads, not assuming a leaky

envelope will provide any fresh air

Supply Air:Supply Air:

• 18 cfm/person (DIN1946)

• OR 0.3 AC/h

• Typ Home: 72 cfm


Ventilation System Layout -Recommendations

Keep Ambient (Outside) Air Ducts Short – place ventilator centrally located, close to envelope

Keep Ambient (Outside) Air Ducts Short – place ventilator centrally located, close to envelope

Well-Insulated w/ Vapor Impermeable InsulationWell-Insulated w/ Vapor Impermeable Insulation

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Keep Conditioned (Inside) Air Ducts

Within the Thermal Envelope

Keep Conditioned (Inside) Air Ducts

Within the Thermal Envelope

Minimize Duct LossesMinimize Duct LossesSource:

www.proairservices.i.e.com


Ventilation System Layout -Best Practice

Smooth InteriorSmooth Interior

Minimize Bends/Kinks/ConstrictionsMinimize Bends/Kinks/Constrictions

Low Velocity (< 3 m/s | ~600fpm)Low Velocity (< 3 m/s | ~600fpm)

Tightly Sealed (< 3% Leakage)Tightly Sealed (< 3% Leakage)

Minimize Duct Losses

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Size for Low & High Speed (Air Flow)Size for Low & High Speed (Air Flow)

Short & Centralized Duct LayoutShort & Centralized Duct Layout

(Use Far-Throwing Diffusers & Coanda Effect)(Use Far-Throwing Diffusers & Coanda Effect)

Intake away from pollutant sources Intake away from pollutant sources

Intake and exhaust hoods min 6’ apart, above snow levels with screened weather hoodsIntake and exhaust hoods min 6’ apart, above snow levels with screened weather hoods

Source:

www.proairservices.i.e.com


Ducts and Ventilator Noise

Sound Attenuation

• Vibration isolate ERV/HRV from floor joists

• Use flex duct or silencers

• to mitigate noise from rigid ducts

Sound Attenuation

• Vibration isolate ERV/HRV from floor joists

• Use flex duct or silencers

• to mitigate noise from rigid ducts

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rigid ducts

• between bedrooms

• Consider sound attenuation in walls/ceiling/floor of mechanical room

rigid ducts

• between bedrooms

• Consider sound attenuation in walls/ceiling/floor of mechanical room

Source: Fantech


Ducts: Exhaust Placement

• in far corner of bathroom

• away from doorBathroomsBathrooms

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• at least 6’ away from cooktop

•with grease filterKitchensKitchens


Ducts: Supply Placement

• Placed high in the room for coanda effect

• Typ. pointed towards windowsBedroomsBedrooms

• Placed high in the room for coanda effect

• Typ. pointed towards windows

Living/Family Rooms

Living/Family Rooms

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• Dependent on occupancy

• For residences, treat as bedroomOfficesOffices

• Supply air similar to other floorsConditioned BasementsConditioned Basements


Duct Layout Single Unit Example

Layout Review:

� Find Exhaust Locations and Flow Rates

� Balance with Supply Locations

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Supply Locations

� No Short Circuits

� Short runs with distribution towards perimeter

� Duct sized properly for flow


Effective Ventilation System Attributes

Ensure Even Distribution Throughout

•Use Adjustable Diffusers

•Set Each Register and Diffuser

•Balance Overall In & Out Flow

Balance the System

(< 10% Diff.)

Balance the System

(< 10% Diff.)

•Use Jump Ducts, Undercut Doors

Overflow Openings Between

Overflow Openings Between

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Doors

•1 Pa Maximum Differential Between RoomsBetween Rooms

• No Recirculating Air StreamsAvoid “Short

Circuits”

Avoid “Short

Circuits”

• Simple Low, Medium or High

• Overrides in Kitchen & BathsControlsControls


Kitchen Ventilation Requirements

•Continuous

•Boost override in kitchen to max

35 cfmKitchen Exhaust

35 cfmKitchen Exhaust

•Good capture efficiency

RecircHoodRecircHood

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efficiencyRecircHoodRecircHood

• Min 6’ from stoveExhaust

placement Exhaust

placement

•MERV 7 filter at kitchen

intakeFiltrationFiltration


IAQ Measured Results

Approx. continuous ventilation rate: 20+ cfm average


VENTILATION STANDARDSVENTILATION STANDARDS


Example: 1,800ft2 (gross), 3 beds

0.01* cfm+ 0.02 cfm * per 1ft2 (gross) + (7.5cfm x # of bedrooms +1)

ASHRAE 62.2-2016

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*ASHRAE calls for 0.03cfm/ft2, but allows 0.02cfm/ft2

infiltration credit

(0.01cfm x 1800) + (0.02cfm x 1800) + (7.5cfm x 4) = 48cfm (mech.) + 36cfm (infiltration) = 84 cfm


ASHRAE 62.2-2016 – Local Exhaust

Kitchens – 100cfm intermittent / has to be directly vented if rate is less than 5 ACH continuous

Bathrooms - 50cfm intermittent / 20cfm continuous

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Example – 10’Wx20’Lx9’H kitchen = 150cfm

This is a problem in medium to big and open kitchens!


ASHRAE 62.2-2016 – Kitchen Exhaust

Workaround 1 – design for intermittent (ERV/HRV on boost pulls 100cfm from kitchen)

Example A – 10’Wx20’Lx9’H kitchen = 1800 ft3 x5ACH/60min = 150cfm

Kitchens – 100cfm intermittent / 5 ACH continuous

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Use booster switch and duct regulators to pull required from the kitchen

Example B: 10’Wx10’Lx9’H space around range = 900 ft3 x5ACH /60min = 75cfm

Workaround 2 – define volume as “reasonable” area surrounding range and design for continuous

kitchen)


ASHRAE 62.2-2016 – NEW

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Combined intake/exhaust for direct kitchen vent if cross contamination is less than 10% as attested by manufacturer in writing.

NOT ALLOWED FOR BALANCED VENTILATION SYSTEMS


IRC 2012 and 2015

Based on square footage/bedrooms of home, s. table below

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1,350ft2 (net), 3 bedrooms = 60cfm



0.01 cfm* per 1ft2 (gross) + (7.5cfm x # of bedrooms +1)

BSC Standard 01(Balanced, intermittently balanced or unbalanced)

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*0.75 credit for balanced distributed systems: 0.75x48cfm = 36cfm

(0.01cfm x 1800) + (7.5cfm x 4) = 48cfm



100 cfm per kitchen+ (7.5cfm x # of bedrooms +1)

BSC Standard 01, additional kitchen exhaust, intermittent, directly exhausted, dampered

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Total ventilation for balanced distributed systems:

= 36cfm + 100 cfm direct intermittent kitchen exhaust

100 cfm x 1= 100 cfm


Passive Buildings Ventilation Requirement, Continuous

Example: 1,800ft2 (gross)…~1,350ft2 iCFA

Minimum 0.30ACH (based on net enclosed volume)

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10,800 x 0.30 / 60 = 54cfm

Approximate volume: 1,350 x 8 = 10,800ft3


Example: 1,800ft2 (gross), 3 beds, 1 kitchen, 2 baths, 1 powder room/laundry

(35cfm x # of kitchens) + (24cfm x # of bathrooms) + (12cfm x # powder room/laundry)

Passive Buildings Ventilation System Capacity Sizing Requirement for Max Extract Air Event

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*Assumes no infiltration to help meet requirement

35cfm + (24cfm x 2) + 12 cfm = 95cfm


Summary System Components

� Air-tight envelope, no infiltration

� Very efficient balanced ventilation

system with heat recovery and filtration

� Duct system

� High quality recirculating range hood to

capture large particles

� Balanced ventilation Kitchen exhaust

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� Balanced ventilation Kitchen exhaust

with boost override and filter at intake

� Overflow provisions at rooms

� If direct exhaust depressurizing

appliances provide make-up air

� If combustion appliances then direct-

vented


Standard Recommendation

� Passive building ventilation standard:

� Sizing requirements, ventilation flow

rates, required local exhaust

� Efficiency requirements by climate

� Testing and commissioning protocols

� Air-tightness and compartmentalization

protocols

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protocols

� Rules for combustion and exhaust

appliances, make-up air

� Filtration requirements

� Duct system requirements, intake,

exhaust placement, insulation

� Specify indoor air quality limits for

VOC/CO2/PM 2.5-10


BEST PRACTICE RECOMMENDATIONS - PHIUS · Intake and exhaust hoods min 6’ apart, above snow levels...

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