the case for energy recovery in addressing … case for energy recovery in addressing commercial...

The Case for Energy

Recovery in addressing

Commercial Building

Indoor Air Quality

Fundamentals

Common Misconceptions

Performance Certification

Applications

Learning Objectives

Improve and broaden dialog concerning the role and

importance of Energy Recovery Ventilation

Define Energy Recovery Ventilation

Review fundamental terms involved in description and

operation of Energy Recovery Ventilation

Review the fundamentals to apply effective and reliable

Energy Recovery Ventilation

Compare and Contrast common Energy Recovery

Ventilation Media

Applications

Why Energy Recovery?

Address issues related to Indoor Air Quality

Improve heath and productivity of occupants

Elevated CO2 levels

Moisture control

Off gassing of Volatile Organic Chemicals

Comply with energy codes

Save energy / reduce energy consumption

Building Functionality and Economics

Reduce HVAC system costs

Indoor Air Quality Basis of Discussion

Rate of ventilation air required, most often by

mechanically induced (forced) outside

(ventilation) air

ASHRAE 62.1 for CII Buildings

ASHRAE 62.2 for low-rise residential buildings

LEED Increases ventilation rates over ASHRAE

standard

What is “Ventilation Air”? The Air used to provide acceptable indoor air quality per

prescribed ventilation rates outlined in ASHRAE Standard 62

HOURS

1.8

1.7

1.6

1.5

1.4

1.3

1.2

1.1

1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

M 1 2 3 4 5 6 7 8 9 10 11 N 1 2 3 4 5 6 7 8 9 10 11 M

PP

M C

O2

(T

HO

US

AN

DS

)

OSHA

800 PPM

CO2 LIMIT

ASHRAE-1000

PPM CO2 LIMIT

PRESCHOOL FACILITY- CO2 levels obseved

Before Ventilation Strategy

OUTDOOR

300-400 PPM CO2

Why Ventilate?

HOURS

1.8

1.7

1.6

1.5

1.4

1.3

1.2

1.1

1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

M 1 2 3 4 5 6 7 8 9 10 11 N 1 2 3 4 5 6 7 8 9 10 11 M

PP

M C

O2

(T

HO

US

AN

DS

)

PRESCHOOL FACILITY- After ERV Installation

OSHA

800 PPM

CO2 LIMIT

ASHRAE-1000

PPM CO2 LIMIT

TIME

CLOCK

TURNED

OFF - ERV

TIME

CLOCK

TURNED

OFF - ERV

Why Ventilate?

OUTDOOR

300-400 PPM CO2

Fundamental Terms Differences in performance and cost is significant

ERV aka:

Energy Recovery

Ventilator

Heat Exchanger

Sensible and Latent

Recovery

Energy Wheel

Static Plate Core

Enthalpy

Enthalpic Plate

HRV aka:

Heat Recovery Ventilator

Sensible Recovery

Heat Exchanger

Energy Recovery Ventilation

Opportunities Every commercial

building needs

ventilation

Cost Benefits

Downsize HVAC equipment

Reduced ductwork

complication

Favorable payback

Quantifiable energy savings

Rebates (where applicable)

Performance Benefits

Decouple ventilation from space

conditioning

Demand control ventilation

Humidity control

Capture exhaust energy

Fundamentals of Energy

Recovery Ventilation

Summer: Pre-cooling /drying of hot & humid

incoming air

Winter: Pre-heating/humidifying of cold & dry

incoming air

Transfers upwards of 55 - 75% of the energy in

the exhaust air stream to fresh air stream

Wheels or Plates are most common

Elements of Properly

Applied ERV

Performance

Media independently certified - AHRI

Ratio between highest energy recovered

vs. lowest device operation energy

consumed in the recovery process • (vs. cost / footprint)

Recovery Efficiency Ratio (Guideline V)


Applied ERV Value

Easy to drop into HVAC systems

Minimal complexity

Minimal maintenance

Minimal commissioning effort


Applied ERV

Reliability

• Performance and operation is consistent

and reliable as HVAC equipment

applied on project

• Confident in downsizing the HVAC

equipment

The Potential for Energy Efficiency -

State of Iowa S. W. Hadley, OAK RIDGE NATIONAL LABORATORY

One-Year Example of Adding

a Commercial 1850 cfm ERV

3.8 tons cooling equipment downsize

(Conventional AC system avoided installed cost

$5,700)

Annual energy savings $2,387.98

Annual demand savings $276.07

Total energy savings $2,664.05

Simple payback: 0.5 years

Software selection tools

General ERV Selection

ERV Selection – Core/Wheel CFM Per air stream (leaving EA/ entering OA)

Static Pressure Drop

Summer/winter weather data (ASHRAE standard)

Electrical voltage, phase and horsepower required to operate

ERV

ERV Selection – Wheel Specific Purge air - Project schedules will show an imbalance of up to

50% between EA/OA

• Common for Wheel ERV to clean media surface

Cross leakage/contamination consideration

Condensate/defrost strategy consideration

Common Energy Recovery

Media / Packages

Core material: Aluminum or Plastic

Core material: Hydroscopic Resin

20-30% total effectiveness

Sensible only recovery

HRV: Heat Recovery Ventilator

Sensible and Latent recovery

ERV: Enthalpy Core


ERV: Enthalpy Wheel


Sensible and Latent recovery

Wheel material: • Aluminum

• Synthetic Fiber

• Polymer

Manufacturers: Fantech, Lifebreath, Venmar

Manufacturers: Greenheck, SEMCO

Manufacturer: RenewAire, S&P, Mitsubishi

HRV: Sensible Core

Numerous Media Manufacturers

Packaged HRV Equipment

Common Transfer material

Aluminum

Polypropylene

Performance

The return and supply airstreams pass

within air passages perpendicular to

each though the plate material

Liquid water is a common byproduct

Critical Media Components

End pans and frame

Defrost

Drain pan

Associated plumbing

ERV: Enthalpy Wheel

Transfer Performance Media rotates between the

airstreams transferring the energy

from exhaust airstream to the

supply airstream

Critical Media

Components Cassette

Bearings

Wheel Segments

Wheel Drive Belt & tensioner

Pulley

Wheel Motor

Frost control

ERV: Enthalpy Wheel

Packaged Options

300 to 20,000 cfm Indoor and Rooftop

Stand Alone Energy

Recovery Ventilator

Energy Recovery

w/Heating

Energy Recovery

w/Heating and Cooling

Energy Recovery

w/Evaporative Cooling

Dedicated Outdoor Air

Systems

ERV: Enthalpy Core

Transfer Performance

Air passages perpendicular to

each airstream though the plate

material

Sensible via conduction

Latent via diffusion

Straight Air Passages

Laminar Flow

Typical Velocity

250 - 500 ft./ min.

Static pressure loss

0.6 – 1.2 inch

ERV: Enthalpy Core

Packaged Options 70 to Unlimited cfm Indoor and Rooftop

Stand Alone Energy

Recovery

Dedicated Outdoor Air

Systems

Energy Recovery

Bypass

Tight Humidity Control

Performance

AHRI Certification

UL 1812 flammability rated

Design and Construction

Symmetrical/well

proportioned

Fully adhered construction

Unobstructed airflow

Similar transfer materials

Critical Media Components

End pans and frame

Attributes of a Superior

Enthalpy Core

Addressing Common

Misconceptions

Media performance, correct equipment sizing and

application, warranty and maintenance influence actual

performance

Static plate core:

Is made of a high engineered polypropylene

Core will not burn

Core will transfer sensible and latent energy

Energy Star does not have a U.S. standard for HRV and

ERV

AHRI-1060 certified versus performance in accordance with

AHRI -1060 standards or some other standard

ERV Design Ideas: Downsize Heating and Cooling Equipment

Retrofit: Preconditioning OA with ERV can allow

conventional Heating and Cooling systems to

remain unchanged

Increases in outdoor air load w/o increasing

the size of the equipment

ERV Design Ideas: Downsize Heating and Cooling Equipment

New: Preconditioning OA with ERV allows for

downsized HVAC equipment • New ERV technology is more reliable making downsizing

more viable

• Oversized H&C equipment is expensive and inefficient

• Increase H&C system efficiency

• Reduce H&C equipment cost

• Payback on ERV cost <5 yrs

• Annual energy savings

ERV Design Ideas: Peak Load Reduction

Oversized AC is inefficient, ineffective and

expensive

Can lead to short cycling

ERV can be a strategy to manage peak

load

Largest contributor to peak load is ventilation

Tie ERV in to BMS or apply zone

approach

ERV Design Ideas: Recirculation of Toilet Exhaust

ASHRAE Standard 62.1-2010, Section 5.16.3.2.5 Class 2 air shall not be transferred in to Class 1 spaces

Exception – When using an energy recovery device, recirculation

from leakage (EATR), carryover or transfer (Purge air) from the

exhaust side of the energy recovery device is permitted

• Not to exceed 10%

Another Option: An AHRI 1060 rated static plate core with no recirculation through

the core for defrost

• 0% EATR

• 0% purge air

ERV Design Ideas: Must Use Ventilation Wheel to Control Humidity

City 75°F WB 73°F WB 70°F WB

Detroit 10 75 238

New York 29 78 495

Washington DC 170 328 735

Columbus 0 149 475

Pittsburgh 0 52 235

Columbus 0 149 475

Boston 11 61 201

When outdoor air conditions are dryer than 70wb, RenewAire total effectiveness is

comparable to most Wheels

At most locations around the US there are very few ventilation hours where the wet

bulb temperature exceeds 70 degrees

National Weather Service 40-year weather data bin hours / 8760 hours p/yr / ASHRAE Design Test

Conditions 95/78

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

0 20 40 60 80 100 120 140 160 180

Wheel

Heat Pipe

Plate

RenewAire

ARI-1060 Winter Sensible

Unit Number

Eff

ec

tive

ne

ss

Median

ARI-1060 Summer Total

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 20 40 60 80 100 120 140 160 180

RenewAire 78 WBWheelHeat PipePlateRenewAire 75 WBRenewAire 73 WBRenewAire 70 WB

Unit Number

Eff

ec

tive

ne

ss

Median

ERV Design Ideas: Zoning ERV

Supports space sensitive, architectural and

historically sensitive building requirements Mechanical room not required

Smaller equipment and smaller duct diameter

• Duct space only required above ceiling

Eliminate large rooftop footprint

Source point controls are low cost and simple Operation is based on ASHRAE ventilation rates

Simple, lower cost, less complex maintenance Maintenance affects the zone, not entire building

ERV Design Ideas: Replace non process exhaust fans with ERV

CFM/watt consumed per airstream (OA/EA) Energy Star standard for bathroom and utility room fans is 2.8 watt

p/cfm (EA only)

ERV cfm/watt can be competitive depending on the manufacturer

Compare and contrast Fan exhausting 100% of heating and cooling

ERV recapturing up to 75% of heating and cooling

ERV Advantages

Payback of ERV: <5 yrs

Advantages of ERV remain for 10+ years

IAQ advantages

ERV Design Ideas: Simple ERV CO2 control with RTU Economizer

Separate static-plate ERV from RTU

RTU economizer runs standard based on

enthalpy control

ERV runs based on CO2 control from the

space

Simple, self-correcting system control!

ERV Design Ideas: Simple ERV CO2 control with RTU Economizer

Economizer conditions: 55F DB OA, cooling mode

RTU opens economizer panel for free cooling

CO2 levels drop quickly in the space

ERV turns off

ERV Design Ideas: Using ERV with a VRF system

VRF fan coil units have strict EAT ranges

Bringing in too much untreated outside air may cause the mixed

EAT to be outside the acceptable range

Using a zoned or central ERV can bring EAT to an acceptable

temperature without needing a full DOAS system!

Typical Heating EAT Range

59°F DB 81°F DB

Typical Cooling EAT Range

59°F WB 75°F WB

ERV Design Ideas: Using ERV with a VRF system

OA 300CFM 5F DB

RA 706 CFM 70F DB

Mixed Air 1006 CFM

50.8F DB

Without ERV: Unacceptable EAT

Typical Heating EAT Range

59°F DB 81°F DB

With ERV: Acceptable EAT

OA 300CFM 51.2F DB

RA 706 CFM 70F DB

Mixed Air 1006 CFM

64.4F DB

Media Performance

Comparisons

HRV, ERV Enthalpy Wheel,

ERV Enthalpy Core

AHRI 1060-2005 Exchange Media Certification

Pressure drop in e.g. @ 100% cfm

Effectiveness @ 100 & 75% rated cfm

for heating and cooling conditions

Sensible

Latent

Total

Exhaust Air Transfer Ratio, Outdoor Air

Correction Factor, and Purge Angle or

Setting (if applicable) at 0.00 in H2O

[0.0 Pa] and two or more pressure

differentials

Tested at Balanced Airflow

Performance at “Standard

Conditions”

Winter -

OA= 35°Fdb, 33°Fwb

RA=70°Fdb, 58°Fwb

Summer -

OA= 95°Fdb, 78°Fwb

RA= 75°Fdb, 63°Fwb

Required by ASHRAE 90.1 Addendum E. and where rebates are available to be

submitted with application

comparison of energy-recovery technologies

Typical Performance

airside pressure drop (per side), in. H2O

0.2 0.8 1.2 0.6 0.4 1.0

coil loop

HRV plate heat exchanger

heat pipe

HRV wheel

ERV wheel

ERV Enthalpy Plate Exchanger


Typical Performance

effectiveness, %

30 60 80 50 40 70

coil loop


heat pipe

HRV wheel

ERV wheel

sensible

sensible

sensible

sensible

sensible latent

sensible latent



Typical Performance

Outdoor Air Correction Factor

100 160 140 120 180

Heat Pipe

HRV Sensible Plate Exchanger

ERV Wheel


110 130 150 170 190


Typical Performance

Exhaust Air Transfer Ratio

0 6 4 2 8

Heat Pipe

HRV Sensible Plate Exchanger

ERV Wheel


1 3 5 7 9

Comparison of energy-recovery technologies

Typical Frosting Conditions

outdoor temperatures at which frosting typically occurs, °F

-50°F 10°F 50°F -10°F -30°F 30°F

coil loop


heat pipe

HRV wheel

ERV wheel

557 hrs

(1788 hrs) 12 hrs

(79 hrs)

7 hrs

(25 hrs)

Chicago, IL 6 AM – 6 PM, weekdays

(all hours, all days)

ERV core

Exchange Media

Flammability Rating

All components pass UL-723 test for burning characteristics of

building materials

Less than 25/50 flame spread/smoke developed rating

The basic standard:

UL 1812 “Ducted Heat Recovery Ventilators.”

National Fire Protection Association (NFPA) 90A and 90B

90A: Standard for air conditioning and ventilating systems

90B: Standard for warm air heating and air conditioning systems

ERV Maintenance

Comparison

Wheel Routine Inspection / Replacement

Components Wheel cassette

Drive belt

Belt motor

Air seals

Defrost

Cleaning Procedure Short soak

Overnight soak

Media Remove and Reinstallation Segments

Entire wheel

Replace Filters

Core

Routine Inspection Core face

Filters

Cleaning Procedure Vacuum core face of any accumulated

particulate

Media Removal and

Reinstallation Not required

Replace filters

ERV Media Warranty

Comparison

Enthalpy Wheel:

Five year warranty

against manufactures

defects and

workmanship * Source: Airexchange

Enthalpy Core

Ten year performance

warranty against

performance

degradation * Source: RenewAire

ERV Application Examples And Common Attributes

Non process exhaust

AHRI 1060 Certified Media Recovery effectiveness

0% Cross Contamination

Zero Purge Air

No active defrost deployed

10-year performance warranty

Zone or Central ERV Approach

Zone Ventilation

Codify all Building Exhaust Points into a Ventilation

List

• Satisfy the intake air of “Suitable Exhausts” with ERV

• Satisfy the Replacement of Non-Recoverable Exhausts with

Makeup Air Equipment

• Satisfy any Remaining Balance of intake air with Fans,

Makeup Air Equipment or the equivalent

Central Ventilation

Feed building ventilation in to one centralized system

Distribute out to individual VAV boxes or fan coils

Integrated

ERV/Fan Coil

in School

Classroom

Applying Energy Recovery –

Zoning HVAC Systems

Zone ERV with DX Air

Handler

Zone Energy Recovery

1 indoor

Horizontal ERV

Two restroom

exhaust points

Exchanging

450 CFM fresh

air into building

Applying Energy Recovery –

Central HVAC Systems

Roof Top Connect in to Air

Handling Unit 14 rooftop ERVs

Exchanging 21,000 CFM

fresh air into building

100% OA Rooftop Application

Fractional Source Point-

Toilet Exhaust

Fractional Rooftop Ventilation

17 rooftop ERVs

Exchanging 60,000 CFM fresh

air into building

Manifold Stack -(3)- CA4X Units

Packaged Air

Conditioning Unit

Fresh Air Blower

Service Area

Exhaust Air Blower

ERV Media Installed in Air Handling System

ERV

Cabinets

ERV Media Integrated

in to HVAC System

1 indoor ERV cabinet

Integrated in to HVAC

system



ERV Core Custom Application:

Hospital Installation 4 indoor ERV cabinets

Integrated in to custom

enclosure and third party

fans and blowers



ERV Core: Custom Modular Air

Handling Unit

Exchanging 6,000

CFM fresh air into

building

Discussion Resources Other Sources ahridirectory.org

ashrae.org/

epa.gov/

hvi.org/ ul.com/global usgbc.org/ energystar.gov/ nfpa.org/index.asp

renewaire.com ERV Calc –

• Define ventilation needs • Equipment sizing • Develop project schedule • Payback analysis • ASHRAE Weather data • RenewAire ERV Product

data – Submittals – Guide specs – Drawings (Revit, PDF, 3D,

DWG)

About RenewAire Downloads

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