benjamin banneker elementary€¦ · michelle baldwin mechanical option dedicated outdoor air...

Benjamin Banneker ElementaryMilford, DE

Michelle M. BaldwinMechanical Option

Benjamin Banneker ElementaryAE Senior Thesis Spring 2003

Michelle BaldwinMechanical Option

Presentation OutlineExisting ConditionsExisting Mechanical SystemAnalysis of Mechanical Redesign

Dedicated Outdoor Air SystemRadiant Panels

Fire ProtectionEconomic AnalysisLightingConclusions



Project TeamOwner: Milford School DistrictMechanical: Furlow AssociatesElectrical: Carew AssociatesStructural: Baker Ingram AssociatesGeneral Contractor: Conventional Builders

Building Cost: $8,195,200Building Size: 64,600 ft2Dates of Construction

Start: January 2002Finish: October 2003

Existing Conditions



ArchitectureBuilding Exterior

Decorative concrete block with a stacked bondPrefinished metal panels Metal awnings



First Floor



Second Floor



Electrical750 KVA transformer208/120 V, 3 phase, 4 wire70 A emergency generator

Classroom LightingDirect/indirect fluorescent suspended fixtures



StructuralStructural steel joists and girdersNon-composite floor system14’ floor to floor height10’ ceiling height

Construction ManagementNew school built on the same site as existing school



Existing Mechanical SystemDedicated Outdoor Air System

Two Energy Recovery Units (ERU)Six Roof-top unitsAir-cooled chillerFire-Tube BoilersTwo-Pipe System

Unit VentilatorsFan Coil UnitsFin-Tube Radiation



Mechanical System Flow Diagram



Existing Mechanical SystemSupply Air Temp: 75˚FTerminal unit supply air temp:

Cooling – 55˚FHeating – 150˚F

Space dew point temp: 57˚FSpace relative humidity: 53%Latent and Sensible load on the terminal units



Mechanical Redesign GoalsRemove the existing terminal units

Add radiant panels

Decouple the Sensible and Latent LoadsDecrease the supply air temperature

Resize the cooling coil

Reduce the dew point temperatureDetermine radiant panel supply water temperature



Mechanical RedesignNoise in Classrooms

Decrease in ability to learn as background noise increasesHVAC systems are the major source of background noise Classroom rating – NC 30dBUnit Ventilators – NC 45dBTypical classroom with unit ventilators –NC 50 - 55dB



Dedicated Outdoor Air System

1. Outdoor air inlet2. Enthalpy Wheel 3. Cooling and

Heating Coils

100% Outdoor Air15 cfm/personEnergy Recovered from the return air stream without mixing



Dedicated Outdoor Air SystemCooling

Outdoor air inlet: 93˚FEnthalpy Wheel outlet: 81˚F

HeatingOutdoor air inlet: 14˚FEnthalpy Wheel outlet: 54˚F



Mechanical Redesign

ERU supply temperature reduced from 75˚F to 50˚F

Resized Cooling Coil

Relative humidity reduced from 53% to 49%Dew point temperature reduced from 57˚F to 54˚FReheat Coils



Radiant Panels

Invensys RCU-166 panelsPiping ConnectionPanel Shape



Radiant PanelsRoom Air Temperature °F 75

Temperature Water Inlet °F 56

Temperature Water Outlet °F 59

Total Ceiling Area in ft2 800

Total RCU Area in ft2 per Module 10.40

Room Ceiling Height ft 8.50

Total Cooling Capacity BTUH/ft2 Active Area 53.41

Water Flow RCU per Module in gal/min 0.37

Total Number of Panels 844



Controls

Thermostat controlHeating CoilsRadiant Panels

Condensation RiskOperable windowsOutdoor humidity



Fire ProtectionIntegration of sprinkler piping and radiant panel piping

Normal Flow controlChilled water supplied to radiant panels

Fire Flow controlWater supplied directly to sprinkler heads



Flow Diagram



Economic AnalysisFirst Cost Analysis

$6,634$39,000$2,760$111,300Total

Condensate Piping

Fan-Coil Units

Fin-Tube Radiators

Unit Ventilators

Equipment Removed

$900$26,498$21,000$11,210$114,109Total

PumpsValvesReheat CoilsPipingRadiant Panels

Equipment Added



Energy AnalysisInitial System Total Cost: $69,414

22.9% Air System Fans

22.6%Cooling

2.2%Heating 1.9%Pumps

29.5%Lights

21.0% Electric Equipment


22.6%Cooling

2.2%Heating 1.9%Pumps

29.5%Lights

21.0% Electric Equipment



Energy AnalysisRedesigned System Total Cost: $ 65,292


23.2%Cooling

4.0%Heating

3.6%Pumps

31.4%Lights 22.3% Electric Equipment


23.2%Cooling

4.0%Heating

3.6%Pumps

31.4%Lights 22.3% Electric Equipment



Economic Analysis SummaryFirst Cost Analysis Summary

$14,024Additional Cost

$1,196,699Total

$173,717Plus

$159,693Minus

$1,182,675Mechanical Cost

Energy Analysis SummaryThe redesigned system is $4,122 less expensive annuallyPayback period is 3.4 years



Lighting30 fc on task surface

1.5 W/ft2

3 types of light fixtures consideredDirect/Indirect fluorescent suspended fixtureDirect recessed fluorescent fixtureDirect fluorescent suspended fixture



Indirect/Direct Suspended Fluorescent Fixtures

48.6 fc1.07 W/ft2



Direct Recessed Fluorescent Fixture

45.6 fc0.89 W/ft2



Direct SuspendedFluorescent Fixture

40.1 fc1.31 W/ft2



Lighting RecommendationDirect fluorescent suspended fixtures40.1 fc > 30 fcNo shadows1.31 W/ft2 < 1.5 W/ft2



ConclusionsAdvantages

Lower Annual Energy CostShort Payback PeriodIncreased System Control FlexibilityIncreased Floor AreaDecreased Background Noise

Increased ComfortIncreased Learning Ability

DisadvantagesMore Complicated ControlsHigher First Cost



ThanksFurlow AssociatesDr. MummaAE DepartmentFriends & Family

?? Questions ??

AE Senior ThesisSpring 2003

benjamin banneker elementary€¦ · michelle baldwin mechanical option dedicated outdoor air...

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