1. Eastern High School Baltimore, MD
Patrick Dempsey
Mechanical Option

2. Project Background Renovation: Historical Building
Multi-Use Owner/Tenant: Johns Hopkins
Project Team
General Contractor: The Whiting Turner Construction Co.
Architect: Kahn & Associates
MEP Consultant: Schlenger/Pitz & Associates
Structural Consultant: Skarda and Associates
Developer/Owner: Johns Hopkins(DOME Real Estate)
Cost: $22 million
MEP Cost: $6 million

3. Existing Mechanical System
Design Objectives
Lack of Basic Cooling System
Limit the Ductwork
Reserve as much tenant space as possible
Energy Recovery
Off Peak Air Conditioning: Ice Storage
Components
4 pipe chilled water/hot water system
3 Weil McClain 588 Boilers(Fuel Oil fired)
2 Carrier water cooled screw chillers
2 Baltimore Air Coil Cooling Towers
1 Ice Storage Tank

4. Existing Mechanical System (cont.)
3. System Characteristics
Ice Storage associated with lab/off peak space use
Shell perspective: limited tenant information

5. Mechanical Redesign Redesign Objectives Pre-Cooling
Re-examine the loads/modeling
Lighting Loads > 2.0 W/sq.ft
Equipment Loads > 4.0 W/sq.ft
Remodel the space using HAP
Reduced the Peak Cooling Load
Focused on cooling system
Reduce the First Cost & Operating Cost
Size down the Equipment
Smaller Chillers: (211 ton < 246 ton)
Smaller Cooling Towers: (227 ton < 272 ton)
Less Ductwork
Down-sized AHU’s
Pre-Cooling
Adjusted Method of Off Peak Air Conditioning

6. First Cost Analysis Savings garnered First Cost Existing: $ 1285453
First Cost Redesign: $
Difference: $ Adjusted(Baltimore): $
Savings garnered
AHU’s saved $
Diffusers/Return Registers $
Ductwork
55000 lbs < lbs $

7. Annual Cost Analysis HAP Calculations (HVAC components only)
Baltimore Gas & Electric Rates
Existing Annual Cost
$ per year for HVAC costs
Redesign Annual Cost
$ per year
Differential
$ per year
Lifecycle Cost
Duration = 15 years
Nominal Interest Rate = 5%
$ saved (Present Value)

8. Pre-Cooling Methodology: Dr. Braun Building Candidacy Modeling
Cool the structure during off peak hours
Float the temperature
Control oriented
Building Candidacy
Significant Structure for thermal storage: Thick Walls
Utility Rate that penalizes peak usage
Mechanical system comfortable with off peak air conditioning
Modeling
Thermostat based ideally
Setpoints
68 degrees Fahrenheit(unoccupied morning cooling)
75 degrees (occupied cooling)
Issues: limited setpoints, temperature profiles
Not feasible
EQUEST
HAP

9. Pre-Cooling Continued
How to model the pre-cooling effect
Utility Based: Trying to Prove Annual Cost savings
Peak shifts to the morning then scales back up in the afternoon
Compare to the Ice Storage Setup
Load profiling
HAP thermostat schedules are limited to 2 setpoints
HAP loading schedules can stagger the load as a percentage on an hourly basis
Simulate the peak shifts using 3 load inputs
Occupancy
Lighting
Equipment
Keep the profiles close to equal(area under the curve)
Adjusted the throttling range(float)

10. Ice Storage Profile

11. Pre-Cooling Profile

12. Load Profiling Results
Annual Cost Analysis(HVAC components only)
Annual Cost of Redesign(Ice Storage): $89710
Annual Cost of Pre-Cooling System: $84915
Differential: $ 4795
Primary Area of Reduction: Cooling
Air Fans, Heating, Pumps, Tower Fans: neglible total diff.
Lifecycle Cost
Duration= 15 years
Nominal Interest Rate = 5%
$ saved (Present Value)

13. Mechanical Redesign Summary
Remodeled building with lowered electrical loads
Resized equipment using newer model saving roughly a quarter of a million dollars in first cost and saving roughly $15000 annually.
Instituted a pre-cooling controlled system taking advantage of the existing off peak air conditioning apparatus.
Pre-cooling saved nearly $5000 annually.
Comparison between original system and smaller pre-cooled system results in nearly $20000 in annual savings.
All savings were tabulated for HVAC costs only.

14. Electrical Impact
Reduced lighting loads led to drastic reductions in the Non-HVAC annual cost
Existing Original System Component Costs
Lighting: $
Equipment: $
Ratios are off
Equipment Reduction would be justifiable but the reduction in peak load was overly generous

15. Electrical Impact Redesign
Redesign Reduced Annual Cost
Original Lighting Cost: $229807
Redesign Lighting Cost: $
Differential: $170358
Distribution
Roughly $ Equipment Cost
4.0 Watts/sq.ft
Savings support reduced loads
Existing Annual Cost: $401122
Redesign: $236032
Differential: $165090
Illusory
Reduced lighting actual loading
Supports the rationale for reduction

16. Schedule Impact Smaller Mechanical System = Shorter Schedule
Major Components
Air Handling Units
Original Schedule: 25 days
New Schedule: days
Ductwork
Original Schedule: 194 days
New Schedule: 133 days
Diffusers & Return Registers
Original Schedule: 114 days
New Schedule: 78 days
Chillers & Towers: no real savings
Difference: days
Conservatively: days saved.

17. Conclusions Reduced MEP First Cost by roughly 20%
Saved $15000 annually just by reducing the lighting loads to accepted levels
Saved another $5000 annually through pre-cooling
Supported my reduced lighting loads by examining the annual costs of the electrical equipment
Achieved a massive reduction in schedule, conservatively reduced to nearly 75 days

18. Acknowledgements Thanks to:
My sponsor, Jimmy Cachola, of Schlenger/Pitz
Penn State AE Faculty
Especially Dr. Mumma, Dr. Srebric, Dr. Freihaut, and Prof. Ling
Prof. Parfitt & Jonathan Dougherty
Special thanks to my thesis advisor: Dr. Bahnfleth
Fellow AE’s
Jason Borowski, Katie McGimpsey, Brad Cordek, Nicole Renno
Family & Friends
Any that I may have left out

19. Questions?