1. pae consulting engineers, inc. Nick Collins, P.E., LEED™ AP
Mechanical Systems
pae consulting engineers, inc.
Nick Collins, P.E., LEED™ AP
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2. ?
Mechanical Systems
What kind of
mechanical system?

3. Mechanical Systems
Install the smallest, most efficient system possible:
Reduce perimeter loads through careful skin design.
Reduce internal loads: laptops, energy star equipment.
Multnomah County Hillsdale Library
Architect: Thomas Hacker and Associates

4. What Factors Determine the Mechanical System Selected?
Building Type
Office
Housing
Education, Higher Ed or Secondary
Industrial
Maintenance
Comfort
Mark O. Hatfield US Courthouse
Architect: BOORA Architects
Sokol Blosser Wine Barrel Storage Facility
Architect: SERA Architects

5. ASHRAE summer and winter comfort zones.

6. Mechanical Systems
Passive vs. Active
PAE Offices

7. Active Systems Cooling Heating Air Distribution COOLING
Direct Expansion
Packaged Rooftop
Chilled Water
Air Cooled
Water Cooled Central
Ground Water
Direct and Indirect
Evaporative Cooling
Distributed Heat Pumps
Active Systems
Cooling
Heating
Air Distribution
HEATING
Hydronic
Conventional Hot Water Boilers
High Efficiency Hot Water Boilers (Gas)
Electric Heat
Gas Fired
Ground Coupled Heat Pump
AIR HANDLING
Central
Rooftop
Penthouse or Inside
Distributed Air Handling
Fan Coils
Unit Ventilators
Heat Pumps

8. Active Cooling Systems
Direct expansion
Chilled water
- Air cooled
- Water cooled
- Ground Water
Direct and indirect
evaporative cooling
Distributed heat pumps

9. Cooling Systems Chilled Water Package Rooftop
First Cost: Lowest potential first cost.
Energy Cost: Higher energy cost.
Maintenance: High maintenance costs - expected life of 15 years.
Comfort: Reasonable – potential acoustical issues.
University of Oregon School of Music & Dance
Architect: BOORA Architects

10. Cooling Systems Chilled Water Air Cooled
First Cost: In conjunction with air handlers.
Energy Cost: Better than rooftop option.
Maintenance: Lowest maintenance cost option - average life of 17 years.
Comfort: High level of comfort.

11. Cooling Systems Water Cooled First Cost: Greatest first cost.
Energy Cost: Lowest Energy cost.
Maintenance: Equipment is highly reliable - chiller life is 27 years.
Comfort: Provides the best in comfort - quiet operation.

12. Ground Source Heat Pumps
GS heat pumps extract geothermal energy to condition buildings.
Very low energy consumption.
Winter – moves heat from the earth to the building
Summer – moves heat from the building to the earth
Automatic controls are used to reverse the direction of the heat transfer

13. Ground Water
PSU Northwest Center for Engineering, Science and Technology.
Ground water well system with extraction and insertion wells.
No Boiler or Cooling Tower
Ground water is used for heating and cooling.

14. Heating Systems Active Systems – Heating Hydronic - Hot water boiler
- High efficiency boiler - condensing
Electric heat
Gas fired

15. Heating Systems Hydronic Heating Systems
Energy Cost: Mid range, between electric heat and high efficiency hot water.
Maintenance: Requires little maintenance.
Comfort: Excellent comfort.

16. Radiant Floor Heating Consistent heating Low energy usage
Slow response time

17. Heating Systems Electric Heat First Cost: Low first cost.
Energy Cost: Very high. This will represent a 100% to 150% increase in energy cost due to rate differences between gas and electric.
Maintenance: Low maintenance.
Comfort:Step control on electric heaters. Acceptable comfort.

18. Active Systems – Air Handling
Central
Distributed
- Fan Coils
- Unit Vents
- Heat Pumps

19. Air Handling Package Air Handler Variable Air Volume Air Handler
Distribution:
Conventional overhead
Underfloor
Lower energy savings - longer economizer cycle
Smaller cooling zone

20. Air Handling Systems Heat Recovery Energy cost: Low energy cost.
Maintenance: Same as air handler.
Comfort: Less than air handler, if provided without coils.

21. Natural Ventilation
Passive Cooling
PAE Offices

22. Advantages of Natural Ventilation
Simple
Lower first cost (15% less)
Lower operating cost (40% less)
User satisfaction through greater control
Elimination of mechanical refrigeration
Less environment impact
No mechanical noise

23. Advantages of Natural Ventilation Option A
Simple
Lower first cost (15% less)
Lower operating cost (40% less)
User satisfaction thru greater control
Elimination of mechanical refrigeration
Less environment impact
No mechanical noise
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24. Disadvantages of Natural Ventilation
Temperature & humidity cannot be tightly controlled
No filtration
Reduced security
First cost higher if back-up A/C system is also required
Exterior noise can be a problem
Less flexible air intake locations – air quality issues
Large openings required with mass
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25. Disadvantages Temperature and humidity cannot be tightly controlled
No filtration
Reduced security
First cost higher if back-up A/C system is also required
Exterior noise can be a problem
Less flexible air intake locations – air quality issues
Rain

26. Strategies Single-sided opening ventilation Cross ventilation
Stack-induced flows through double opening

27. Washington School for the Deaf
Classroom Natural Ventilation
Daylighting
Thermal Mass
Night Flush
No Filtration

28. Thermal Mass / Night Ventilation
Need approximately 2 to 3 times the floor area
Can reduce maximum daytime temperature

29. Sustainable Design Mechanical Systems
What system? That depends . . .
Reduce loads to lowest possible amount
Know your client, maintenance, comfort, operating schedule, etc.
Select most efficient system possible
System Types
- Active
- Passive
- Mixed Mode

30. Shattuck Hall – Case Study Existing Mechanical Systems
Two dedicated outside air units with steam heat, evaporative air cleaners
Multiple air zones with mix dampers
Gravity relief from each zone (open relief duct on roof)
Other smaller mechanical
systems.
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31. Existing Classroom
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32. Old Zone Dampers - Mixing
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33. Mechanical Systems Options
HVAC Option C – Conventional VAV
Hot water heating
Variable volume AHU’s
Medium pressure supply ductwork
VAV air terminal units in each space
Low pressure return ductwork
Return air plenums
HVAC Option D – Dedicated OA/Radiant
Hot water heating radiant panels
Fan-induced ventilation
Operable windows – manual
New AHU’s/Existing ductwork - for minimum outside air
Radiant Cooling – radiant cooling panels or chilled beams
HVAC Option A – “Natural” Ventilation
Hot water heating radiators
Operable windows – automatic, with trickle vents
Building Mass/Night Flush Cooling
  HVAC Option B – “Natural” Ventilation/Mixed Mode
Fan-induced ventilation
Operable windows automatic
New AHU’s/Existing Ductwork
Cooling coils in new AHU’s deliver cold air through existing ductwork on extremely hot days
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34. Shattuck Hall New Mechanical Systems
Two dedicated outside air units with hot water heating, campus chilled water and filters
Temperature zones with VAV terminal units
Radiant heating and cooling panels
Gravity relief from each zone (open relief duct on roof)
Other smaller mechanical
systems.
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35. Estimated Energy Usage
Energy Use in Shattuck Hall
Estimated Energy Usage
No envelope upgrades
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36. Radiant Panel Concerns
Guinea Pig or Innovative
Comfort
Noise
Condensate
Valve locations
Hot water leaks
Flexibility
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37. Radiant Panels and Valves
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38. Heat
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39. Radiant Ceiling Heating / Cooling
Dedicated outside air for dehumidification
Low mass means faster response time
Uniform heating and cooling
Low energy usage
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