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Students Waste Water Buildings Energy

Deep retrofits: You get what you pay for

Leslie Kramer, Stanford University and Jonathan Schoenfeld, kW Engineering

June 17, 2014

Whole Building Energy Retrofit Program

• Deep retrofits in highest energy using buildings on campus

• Maximizes energy savings in each building within cost-effectiveness criteria

• Looks at a package of measures: no cream skimming

• Big payoffs from in-depth energy audit, advanced control strategies, and relentless performance testing.

WBERP Process

Supplemental and Pre-

Construction Studies

Construction Commissioning

Phase 1&2

Studies

Bid Docum

ents

Construction

& Commissionin

g Suppor

t

M&V Report

Consulting Engineers

Contractors

Review

Studies

Construction

and Commissioni

ng Suppo

rt

1st Year

Tuning and

Monitoring

Persistence

Tracking

Achieve ROI

Stanford Team

• Savings of $3.5 million per year to date• Total cost $14.6 million to date• PG&E rebates of $2 million• Overall simple payback period under 4 years

Results

Case Study: Packard

• $400,000/year energy cost• 3 stories and a basement• Faculty and grad student offices

and dry labs• Built in 2000• Chilled water, steam and electricity

from Stanford’s central plant• 122,500 gross square feet• 4 Air Handlers, 212 VAV boxes• 12 fan coils for additional cooling• VAV boxes controlled by pneumatic thermostats• DDC control of air handlers

INITIAL BASELINE CONDITIONS: NOT BAD!

Energy Audit Process

ASHRAE Level I Rough savings estimates Go/No-Go decision for measure

analysis

Level II (Measure Analysis) Limited trend review Calibrated eQUEST Model

-

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Elec

tric

ity U

sage

(kW

h) Billing Data

Model Output

Audit Findings No-cost Measures

Increase zone setpoints for unoccupied rooms Schedule how water pumps

Low-cost Measures Daylighting controls Eliminate air handler heating coil operation

when economizing Zone Level DDC Conversion

Deadband thermostats Pressure and Supply Air Temperature Resets Zone scheduling and override

Zone Level DDC Implementation Options

Design-Bid-Build Develop request for proposal (RFP) for design Develop design documents Bid construction

Design-Build Develop RFP Bid design-construction

Design-Assist with Performance Specification Energy consultant develops performance specification Bid design-construction

Performance Specification Development

• Input from Multiple Parties– Stanford Facilities Energy

Management Team– Stanford Energy Management

& Control Systems (EMCS)– ACCO & Sunbelt Controls – kW Engineering

• Key Contents:– Equipment specifications– Hardware installation including

control hardware locations and

wiring pathways – System integration– System architecture & control

schematics– Sequence of operations

Basis of Energy Savings

VAV box w/ New DDC controls Existing Air Handling Unit (AHU)

Cooling, Heating, Damper RequestsAirflows

Supply air temp. (SAT) and duct static pressure (DSP) setpoints

Schedule & Setpoints

SAT & Status

Existing DeltaV Control System

• New DDC Thermostats with 4°F deadband• Improved scheduling with standby mode• DSP & SAT reset• Global zone setpoint control for curtailment

Energy Savings

Ensuring Persistence of Performance

• Fully programmable controllers• NiagaraAX Framework• Distech Controls• Spare I/O & controller memory

Flexibility & Future Growth

• Floor level maps color coded by temp./damper

• Zone summaries in tabular format• Intelligent alarming• Quality components

Diagnostics

• Submittal review• Detailed functional testing of 10% sample• 72 hour trend review of additional sample• 3rd party Cx Agent

Commissioning

Commissioning Findings (UPDATE Graphic)

Verified Energy Savings

y = 3.9185x + 624.05R² = 0.9699

y = 2.2642x + 536.56R² = 0.9641

0

500

1,000

1,500

2,000

2,500

0 100 200 300 400

Chill

ed W

ater

Usa

ge(t

on-h

rs/d

ay)

Cooling Degree Days (CDD)

Baseline

Post-Retrofit

Figure 3: Relationship between chilled water usage data and CDD

Verified Energy Savings

y = 41.46x + 8864.7R² = 0.9635

y = 40.001x + 1782.2R² = 0.9881

02,0004,0006,0008,000

10,00012,00014,00016,00018,00020,000

0 50 100 150 200 250

Stea

m U

sage

(lbs/

day)

Heating Degree Days (HDD)

Baseline

Post-Retrofit

Figure 4: Relationship between steam usage data and HDD

Verified Energy Savings

Annual Energy and Cost Savings Project Payback

Electricity Savings (kWh)

Chilled Water Savings (ton-hrs)

Steam Savings (lbs.)

Total Cost Savings Measure Cost Utility

Incentive Simple

Payback (yr)

273,663 134,415 3,359,064 132,569$ 625,514$ 43,455$ 4.4

Verified (Post-Retrofit)

Efficiency Measures Still Available

50.0 55.0 60.0 65.0 70.0 75.0 80.0 85.0 90.0

12 AM 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM 12 AM

Tem

pera

ture

(F)

Time of Day

Normal Day

Cooling Setpoint Heating Setpoint Zone Setpoint

• Global temperature adjustment

• Occupancy based scheduling

Take-Aways

• Private, not-for -profit institution

• 8,500 acres• Oldest buildings from

1890s• Santa Clara County is

the main jurisdiction• >14 million square

feet, 700 buildings• ~$70 million annual

utilities spend

• Deeper savings require a comprehensive approach

• Even relatively new buildings may have out-of-date control systems that are wasting energy

• A detailed specification ensures maintenance and energy savings persist

• Consider using energy-experts with input from all parties to specify, commission and verify control systems

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