Ian Doebber Handout

Designing High Performance Schools in New OrleansSchools in New Orleans

Gulf Coast Green

Ian Doebber

April 16, 2009

NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC

NREL Building Technologies ProgramNREL is a national lab for the US Department of Energy with a single mission

to develop and promote renewable and energy efficiency technologies

• Commercial & Residential Building Energy Efficiency

• Technical Assistance to DOE’s EnergySmart Schools Program

• Advanced EnergyDesign Guides

• Computer Simulation Tool Development

National Renewable Energy Laboratory Innovation for Our Energy Future

Presentation Overview

• K-12 Advanced Energy Design Guide

• Rebuilding New Orleans Schools : Quick Start Schools

• High Performance Schools in Humid Climates


K-12 Advanced Energy Design GuideGuidelines, based on climate zones, to help K-12

school owners and designers achieve 30% energy savings over ASHRAE 90 1 – 1999savings over ASHRAE 90.1 – 1999

• Recommendations only, not a code y,or standard

• Applies to new construction and major renovation

• Case studies showcase schools ti id th t h hi dnationwide that have achieved or

exceeded 30% energy savings


Focus of Recommendations

Building envelope– Fenestration– Wall/Roof Insulation

Lighting systemsD li hti– Daylighting

– Electrical lights

Heating, ventilation and air-conditioning (HVAC) systemsg, g ( ) y– Building automation and controls– Outside air (OA) treatment

S i t h ti (SWH)Service water heating (SWH)

Guide looks at integration of these systems –Guide looks at integration of these systems savings goal dependent on the interaction


Where to get the K-12 AEDG?www.ashrae.org/freeaedg

Download a copy at no charge -or- Purchase a print copy

• 170,500 AEDGs have beenhave been downloaded or sold

• 13,000 AEDG-K-12 hard copies provided a d cop es p o dedto every school district


Quick Start SchoolsS h tiRFQs Schematic

DesignConstruction Documents

Construction 2009 Opening

LEED for Schools Silver : 30% Utility Savings over AHSRAE 90.1 - 2004y g

Kick Off Design Charrette – Guided based on the K-12 AEDG

Next 10 Years

~44 New Schools

>40 Major Renovations


Quick Start Schools: Lighting Design

ZONE CATEGORYPROPOSED LPD

[W/ft2]

OFFICE 1.0

CONFERENCE ROOM 1 0

ASHRAE 90.1 – 2004

1 4 W/ft2 CONFERENCE ROOM 1.0

GENERAL CLASSROOM 1.2

COMPUTER CLASSROOM 1.2

ART CLASSROOM 1.3

SCIENCE LAB 1 4

1.4 W/ft2

SCIENCE LAB 1.4

MEDIA CENTER 1.1

LOBBY/PREFUNCTION 0.8

AUDITORIUM n/a

MUSIC/THEATER/DANCE 1 4

K-12 AEDG

1 1 W/ft2 MUSIC/THEATER/DANCE 1.4

GYM (play area) 1.2

GYM (spectator area) 1.2

FITNESS CENTER 0.8

LOCKER ROOMS 0 6

1.1 W/ft

Quick Start Schools LOCKER ROOMS 0.6

KITCHEN 1.1

WALKIN FREEZER D 0.4

WALKIN COOLER D 0.4

Quick Start Schools

0.8 – 0.9 W/ft2


SERVERY 1.2

DINING AREA 0.7

CORRIDOR 0.58% - 10% saving!!

Quick Start Schools: Daylighting Design

From AEDG Classroom Daylighting Recommendations


Quick Start Schools: Cooling Systems

OA Pre-Treatment Main System

Water CooledDesiccant Wheel

Water CooledMagnetic BearingCentrifugal ChillerCentrifugal Chiller

Chilled WaterWater CooledHi h Effi iChilled Water High EfficiencyScrew Chillers

Enthalpy Wheels&

Air CooledScrew Chillers


Packaged DX Units

Quick Start Schools: Savings

Percent Savings Annual Utility Savings*

26.2% $98,000 [$0.45/ft2]

30.5% $98,000 [$0.61/ft2][ ]

35.1% $77,500 [$0.80/ft2]


*Based on Energy Model

Quick Start Schools: Lesson Learned

Feedback to the next phase K-12 AEDG• More Aggressive Lighting Designo e gg ess e g g es g• Classroom Daylighting (Solving Glare-More Flexibility)• Demand Controlled Ventilation (System or Zone)• Insulation Levels (integrate with infiltration reduction)

Major Short Coming was FOCUSING how following th K 12 AEDG R d ti REQUIREDthe K-12 AEDG Recommendations REQUIRED a dedication to conquering Humidity otherwise forgo significant thermal comfort and energy performance


significant thermal comfort and energy performance

High Performance in Humid ClimatesStory of an Architect and Two Engineers…

Previous Success : LEED Platinum on a High Rise OfficePrevious Success : LEED Platinum on a High Rise Office Building in Phoenix, AZ

Project Scope100,000 ft2 K-5 Elementary School in New Orleans

Conceptual Design thru Construction Administration

LEED for Schools Silver


Minimum of 23% Utility Savings over ASHRAE 90.1-2004

Designing within SilosM i i d D li h iArchitect Silo Maximized Daylighting0.8 W/ft2 LPDbuilding [1.1 W/ft2 LPDclassroom ]High Performance Glazing

Engineer 1 Silo

High Performance Glazing

Zone by Zone HumidistatsEngineer 1 Silo

“Loads Based”

Zone by Zone HumidistatsVentilation : ∑cfm/occ + ∑cfm/ft2

Loads as Usual : 1.4 W/ft2 LPDclassroomclassroom

0.3 ACH Infiltration…

Engineer 2 Silo

“S t B d”

High EER Roof Top UnitsHigh COP/IPLV Centrifugal ChillerP i M t


“System Based” Premium MotorsEfficient Centrifugal Airfoil Fans

Resultant School’s Performance

Each Silo’s Design Focus was Implemented EXACTLY

After a year of operation

EXACTLY

After a year of operation…

Complaints of Cold, Damp Conditions

Extremely High Utility Bills

With 4 more schools under design, School District decided to form a Forensics Team


District decided to form a Forensics Team

Building Forensics : Infiltration

Problem : Increased Fenestration Details

0.3 ACH 1.0 to 1.5 ACH

Remedy : Sealed Construction Details but too

Can not rely on Building Pressurization!


yexpensive to fix vestibules

Building Forensics : Duct Leakage

Looking at Testing and Balancing Report yielded ~30% Leakage Rate

Remedy : Reduced to ~10% Leakage Rate byRemedy : Reduced to 10% Leakage Rate by improving to seal class B based on ASHRAE 90.1 following SMANCA Guidelines


g

Building Forensics : RTU Sizing/ControlProblem : Relying on Rules of Thumb and Lack of

Communication

Roof Top Units oversized and short cycling

Direct Evaporative CoolingDirect Evaporative Cooling

Remedy : Replaced with smaller Roof Top Units?Anyone else got any cheaper ideas?


y g y

Building Forensics : VentilationProblem : Misinterpretation of ASHRAE 62.1 Ventilation

Rate Procedure for Multi-Zone Systems

Ventilation =∑cfm/occ + ∑cfm/ft2All Zones All Zones

No Diversity 50 ft2 / occNo Diversity 50 ft / occ

4 6 times actual school population4 – 6 times actual school population

Remedy : Calculated necessary Ventilation and


Remedy : Calculated necessary Ventilation and reduced Outdoor Air Intake

Building Forensics : Reheat DilemmaProblem : Limitation of using only DX or Chilled Water

Coils to provide both Cooling and Dehumidification

When the supply air flow required to dehumidify the space exceeded the

R d 1 Eli i t Z b Z H idi t t

y psupply air flow required to meet 75ºF.

Result 1 : Cold, Damp Conditions

Remedy 1 : Eliminate Zone by Zone Humidistats

Remedy 2 : Do Nothing


Result 2 : Significant Reheat yielding High Utility Bills

Psychometric Review 1Properties of Air

Temperature Moisture Content

RelativeHumidity

mass of watermass of dry airMoisture Content =

grains of waterd f d i

=


pound of dry air

Psychometric Review 2

Imagine 100% Relative Humidity

100% Relative Humidity

50% Relative Humidity

at these Temperatures 110 gr/lb

Humidity y

80 gr/lb

40 gr/lb

55 gr/lb

40 gr/lb


40ºF 50ºF 60ºF 70ºF

Conventional System Siamese Twins : Temperature & Moisture Content

FanDXTemperature PotentialFanDX

-or-Chilled Water 65 gr/lb

Potential

Water

57 gr/lb

65 gr/lbMoisture Potential


75ºF52ºF 55ºF 75ºF

North Facing Classroom1,000 ft2 Classroom

31 occupants

1 4 W/ft2 Li hti

Lights Off 1.4 W/ft2 Lighting

0.9 W/ft2 Plug LoadNo Plug Load

0.3 ACH Infiltration

R-13 Walls / 0.5 SHGCCl d

Supply Air = 55ºF & 57 gr/lb

0.4% Design Day Conditions (Sunny)

Space Air = 75ºF & 65 gr/lb

Cloudy

pp y g

Thermal Load Requires = 1,000 cfm500 cfm

Moisture Load Requires = 850 cfm

Psychometric ChartCold and Damp are the Worst Conditions in Regarding Reheatg g

65 gr/lb

75ºF


75ºF

Technologies to Battle HumidityF ll i S t id E Effi i t tFollowing Systems provide Energy Efficient way toSupply Air at HIGHER Temperature (55ºF to 65ºF) but

1. Hot Gas Reheat

LOWER Moisture Content (57 gr/lb to 53 gr/lb)

2. Heat Pipe or Sensible Wheel

3. Desiccant Wheels

4. Enthalpy Wheels

5. Combination of all of the above

Hot Gas Reheat

DX Hot Gas

65 /lb

Gas

65 gr/lb

53 gr/lb


75ºF65ºF50ºF

Heat Pipe or Sensible WheelH t PiHeat Pipe or

Sensible Wheel

Exhaust Air

65 /lbDX

65 gr/lb

53 gr/lb-or-

Chilled Water


75ºF65ºF50ºF

Desiccant WheelsHot Gas

65 /lbDX

65 gr/lb

53 gr/lb


75ºF65ºF57ºF

Enthalpy Wheels - Regenerative Braking

Exhaust

Most Cost Effective Means of Dehumidification

Air

65 /lbDX Hot

65 gr/lbGas53 gr/lb


75ºF65ºF50ºF

Enthalpy Wheel & Heat PipeHeat Pipe or

Exhaust

Heat Pipe or Sensible Wheel

Air

65 /lbDXor 65 gr/lb

53 gr/lb

-or-Chilled Water


75ºF65ºF50ºF

Dedicated Outdoor Air System (DOAS)T if t D lTrifecta Decouple

1. Moisture - Centralized System that provides “Dry” (~50 gr/lb) Outdoor Air between 55ºF 75ºF (~65ºF)(~50 gr/lb) Outdoor Air between 55ºF-75ºF (~65ºF)

2 T t L l F C il U it W t S2. Temperature – Local Fan Coil Units or Water Source Heat Pumps to maintain 75ºF setpoint

3. Ventilation – Dampers on 100% Outdoor Airon 100% Outdoor Air Supply controlled by Zone CO2 sensor


K-12 AEDG

What Happened to our Design Team

1. Used the K-12 AEDG as a starting point :-Lighting Designg g g-Daylighting Design-Envelope DesignSt t d th Di i f M h i l S t-Started the Discussion of Mechanical Systems

EARLY in Conceptual Design

2. Focused on how to conquer humidity by balancingEnergy Efficient Dehumidification while minimizing gy gReheat


Architects Review

Infiltration : Focus on Construction Details and Vestibule Design to minimize Infiltration

Access to Exhaust Air : Coordinate room layout to provideAccess to Exhaust Air : Coordinate room layout to provide access to Exhaust Air

Coordinate Space Requirements : Equipment using Desiccantor Enthalpy Wheels often need double height spacepy g p

Reference : “ASHRAE Humidity Control Design Guide”


Reference : ASHRAE Humidity Control Design Guide

Engineer

Duct Leakage : at least leakage class B

Ventilation : Understand ASHRAE 62 1 VentilationVentilation : Understand ASHRAE 62.1 Ventilation Requirements but do not need to Over Ventilate

Start the Mechanical Conversation EARLY : Work with the rest of the Design Team in Conceptual or Schematic Design to determine the Optimal Systemthe Optimal System

Energy Efficiency Dehumidification without Comprimising ReheatEnergy Efficiency Dehumidification without Comprimising Reheat


READ “ASHRAE Humidity Control Design Guide”

Ian Doebber Handout

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