Designing High Performance Schools In New Orleans

Designing High Performance Schools in New Orleans 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 Gulf Coast Green Ian Doebber April 16, 2009

NREL Building Technologies Program

NREL is a national lab for the US Department of Energy with a single mission to develop and promote renewable and energy efficiency technologies

National Renewable Energy Laboratory Innovation for Our Energy Future

Commercial & Residential

Building Energy Efficiency

Technical Assistance to

DOE’s EnergySmart

Schools Program

Advanced Energy Design Guides

Computer Simulation Tool Development

Presentation Overview

K-12 Advanced Energy Design Guide

Rebuilding New Orleans Schools : Quick Start Schools

High Performance Schools in Humid Climates

National Renewable Energy Laboratory Innovation for Our Energy Future

K-12 Advanced Energy Design Guide National Renewable Energy Laboratory Innovation for Our Energy Future

Guidelines, based on climate zones, to help K-12 school owners and designers achieve 30% energy savings over ASHRAE 90.1 – 1999

Recommendations only, not a code

or standard

Applies to new construction and

major renovation

Case studies showcase schools

nationwide that have achieved or

exceeded 30% energy savings

Focus of Recommendations

Building envelope

Fenestration

Wall/Roof Insulation

Lighting systems

Daylighting

Electrical lights

Heating, ventilation and air-conditioning (HVAC) systems

Building automation and controls

Outside air (OA) treatment

Service water heating (SWH)

Guide looks at integration of these systems – savings goal dependent on the interaction National Renewable Energy Laboratory Innovation for Our Energy Future

Where to get the K-12 AEDG? National Renewable Energy Laboratory Innovation for Our Energy Future www.ashrae.org/freeaedg

170,500 AEDGs have been downloaded or sold

13,000 AEDG-K-12 hard copies provided to every school district

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

Quick Start Schools National Renewable Energy Laboratory Innovation for Our Energy Future RFQs Schematic Design Construction Documents Construction 2009 Opening Next 10 Years ~44 New Schools >40 Major Renovations LEED for Schools Silver : 30% Utility Savings over AHSRAE 90.1 - 2004 Kick Off Design Charrette – Guided based on the K-12 AEDG

Quick Start Schools: Lighting Design National Renewable Energy Laboratory Innovation for Our Energy Future ASHRAE 90.1 – 2004 1.4 W/ft 2 K-12 AEDG 1.1 W/ft 2 Quick Start Schools 0.8 – 0.9 W/ft 2 8% - 10% saving!! 0.5 CORRIDOR 0.7 DINING AREA 1.2 SERVERY 0.4 WALKIN COOLER D 0.4 WALKIN FREEZER D 1.1 KITCHEN 0.6 LOCKER ROOMS 0.8 FITNESS CENTER 1.2 GYM (spectator area) 1.2 GYM (play area) 1.4 MUSIC/THEATER/DANCE n/a AUDITORIUM 0.8 LOBBY/PREFUNCTION 1.1 MEDIA CENTER 1.4 SCIENCE LAB 1.3 ART CLASSROOM 1.2 COMPUTER CLASSROOM 1.2 GENERAL CLASSROOM 1.0 CONFERENCE ROOM 1.0 OFFICE [W/ft2] PROPOSED LPD ZONE CATEGORY

Quick Start Schools: Daylighting Design National Renewable Energy Laboratory Innovation for Our Energy Future From AEDG Classroom Daylighting Recommendations

Quick Start Schools: Cooling Systems National Renewable Energy Laboratory Innovation for Our Energy Future OA Pre-Treatment Main System Desiccant Wheel Water Cooled Magnetic Bearing Centrifugal Chiller Chilled Water Enthalpy Wheels & Packaged DX Units Water Cooled High Efficiency Screw Chillers Air Cooled Screw Chillers

Quick Start Schools: Savings National Renewable Energy Laboratory Innovation for Our Energy Future Percent Savings Annual Utility Savings* 30.5% $98,000 [$0.61/ft 2 ] 35.1% $77,500 [$0.80/ft 2 ] 26.2% $98,000 [$0.45/ft 2 ] *Based on Energy Model

Quick Start Schools: Lesson Learned National Renewable Energy Laboratory Innovation for Our Energy Future

Feedback to the next phase K-12 AEDG

More Aggressive Lighting Design

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 the K-12 AEDG Recommendations REQUIRED a dedication to conquering Humidity otherwise forgo significant thermal comfort and energy performance

High Performance in Humid Climates National Renewable Energy Laboratory Innovation for Our Energy Future Story of an Architect and Two Engineers… Previous Success : LEED Platinum on a High Rise Office Building in Phoenix, AZ Project Scope 100,000 ft 2 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 Silos National Renewable Energy Laboratory Innovation for Our Energy Future Architect Silo Engineer 1 Silo “ Loads Based” Engineer 2 Silo “ System Based” Maximized Daylighting 0.8 W/ft 2 LPD building [1.1 W/ft 2 LPD classroom ] High Performance Glazing Zone by Zone Humidistats Ventilation : ∑cfm/occ + ∑cfm /ft 2 Loads as Usual : 1.4 W/ft 2 LPD classroom 0.3 ACH Infiltration… High EER Roof Top Units High COP/IPLV Centrifugal Chiller Premium Motors Efficient Centrifugal Airfoil Fans

Resultant School’s Performance National Renewable Energy Laboratory Innovation for Our Energy Future After a year of operation… Complaints of Cold, Damp Conditions Extremely High Utility Bills Each Silo’s Design Focus was Implemented EXACTLY With 4 more schools under design, School District decided to form a Forensics Team

Building Forensics : Infiltration National Renewable Energy Laboratory Innovation for Our Energy Future Problem : Increased Fenestration Details 0.3 ACH 1.0 to 1.5 ACH Remedy : Sealed Construction Details but too expensive to fix vestibules Can not rely on Building Pressurization!

Building Forensics : Duct Leakage National Renewable Energy Laboratory Innovation for Our Energy Future Looking at Testing and Balancing Report yielded ~30% Leakage Rate Remedy : Reduced to ~10% Leakage Rate by improving to seal class B based on ASHRAE 90.1 following SMANCA Guidelines

Building Forensics : RTU Sizing/Control National Renewable Energy Laboratory Innovation for Our Energy Future Remedy : Replaced with smaller Roof Top Units? Anyone else got any cheaper ideas? Roof Top Units oversized and short cycling Problem : Relying on Rules of Thumb and Lack of Communication Direct Evaporative Cooling

Building Forensics : Ventilation National Renewable Energy Laboratory Innovation for Our Energy Future Problem : Misinterpretation of ASHRAE 62.1 Ventilation Rate Procedure for Multi-Zone Systems No Diversity 50 ft 2 / occ 4 – 6 times actual school population Remedy : Calculated necessary Ventilation and reduced Outdoor Air Intake Ventilation = ∑cfm/occ + ∑cfm /ft 2 All Zones All Zones

Building Forensics : Reheat Dilemma National Renewable Energy Laboratory Innovation for Our Energy Future Problem : Limitation of using only DX or Chilled Water Coils to provide both Cooling and Dehumidification Result 1 : Cold, Damp Conditions Remedy 1 : Eliminate Zone by Zone Humidistats When the supply air flow required to dehumidify the space exceeded the supply air flow required to meet 75 ºF . Result 2 : Significant Reheat yielding High Utility Bills Remedy 2 : Do Nothing

Psychometric Review 1 National Renewable Energy Laboratory Innovation for Our Energy Future Properties of Air Temperature Moisture Content Relative Humidity mass of water mass of dry air Moisture Content = grains of water pound of dry air =

Psychometric Review 2 Imagine 100% Relative Humidity at these Temperatures National Renewable Energy Laboratory Innovation for Our Energy Future 40 ºF 40 gr/lb 50 ºF 55 gr/lb 80 gr/lb 60ºF 110 gr/lb 70ºF 100% Relative Humidity 50% Relative Humidity

Conventional System National Renewable Energy Laboratory Innovation for Our Energy Future 75ºF Fan DX -or- Chilled Water 65 gr/lb 75ºF Siamese Twins : Temperature & Moisture Content 52ºF 55ºF 57 gr/lb Moisture Potential Temperature Potential

North Facing Classroom 1,000 ft 2 Classroom 31 occupants 1.4 W/ft 2 Lighting 0.9 W/ft 2 Plug Load 0.3 ACH Infiltration Supply Air = 55 ºF & 57 gr/lb R-13 Walls / 0.5 SHGC 0.4% Design Day Conditions (Sunny) Space Air = 75 ºF & 65 gr/lb Thermal Load Requires = 1,000 cfm Moisture Load Requires = 850 cfm Cloudy Lights Off No Plug Load 500 cfm

Psychometric Chart National Renewable Energy Laboratory Innovation for Our Energy Future 75ºF 65 gr/lb Cold and Damp are the Worst Conditions in Regarding Reheat

Technologies to Battle Humidity

Hot Gas Reheat

Heat Pipe or Sensible Wheel

Desiccant Wheels

Enthalpy Wheels

Combination of all of the above

Following Systems provide Energy Efficient way to Supply Air at HIGHER Temperature (55ºF to 65 º F) but LOWER Moisture Content (57 gr/lb to 53 gr/lb)

Hot Gas Reheat National Renewable Energy Laboratory Innovation for Our Energy Future 65 gr/lb 75ºF DX Hot Gas 53 gr/lb 65ºF 50ºF

Heat Pipe or Sensible Wheel National Renewable Energy Laboratory Innovation for Our Energy Future 65 gr/lb 75ºF DX Heat Pipe or Sensible Wheel Exhaust Air -or- Chilled Water 53 gr/lb 65ºF 50ºF

Desiccant Wheels National Renewable Energy Laboratory Innovation for Our Energy Future 65 gr/lb 75ºF DX Hot Gas 53 gr/lb 65ºF 57ºF

Enthalpy Wheels - Regenerative Braking National Renewable Energy Laboratory Innovation for Our Energy Future 65 gr/lb 75ºF DX Exhaust Air Hot Gas Most Cost Effective Means of Dehumidification 53 gr/lb 65ºF 50ºF

Enthalpy Wheel & Heat Pipe National Renewable Energy Laboratory Innovation for Our Energy Future 65 gr/lb 75ºF Exhaust Air Heat Pipe or Sensible Wheel DX -or- Chilled Water 53 gr/lb 65ºF 50ºF

Dedicated Outdoor Air System (DOAS) National Renewable Energy Laboratory Innovation for Our Energy Future

Trifecta Decouple

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

2. Temperature – Local Fan Coil Units or Water Source Heat Pumps to maintain 75ºF setpoint

3 . Ventilation – Dampers on 100% Outdoor Air Supply controlled by Zone CO2 sensor K-12 AEDG

What Happened to our Design Team National Renewable Energy Laboratory Innovation for Our Energy Future

Used the K-12 AEDG as a starting point :

-Lighting Design

-Daylighting Design

-Envelope Design

-Started the Discussion of Mechanical Systems EARLY in Conceptual Design

2. Focused on how to conquer humidity by balancing

Energy Efficient Dehumidification while minimizing Reheat

Architects Review National Renewable Energy Laboratory Innovation for Our Energy Future Infiltration : Focus on Construction Details and Vestibule Design to minimize Infiltration Access to Exhaust Air : Coordinate room layout to provide access to Exhaust Air Coordinate Space Requirements : Equipment using Desiccant or Enthalpy Wheels often need double height space Reference : “ASHRAE Humidity Control Design Guide”

Engineer National Renewable Energy Laboratory Innovation for Our Energy Future Start the Mechanical Conversation EARLY : Work with the rest of the Design Team in Conceptual or Schematic Design to determine the Optimal System Duct Leakage : at least leakage class B READ “ASHRAE Humidity Control Design Guide” Ventilation : Understand ASHRAE 62.1 Ventilation Requirements but do not need to Over Ventilate Energy Efficiency Dehumidification without Comprimising Reheat