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SBA Course Unit 3 Mechanical Systems
- 1. G SBA Course Unit 3 Mechanical Systems November 24, 2012
- 2. Agenda 1. Intro to Energy 2. Design Principles 3. HVAC Systems 4. Controls/Commissioning/Operations 5. The Game
- 3. Who we are Erich Rohmann, B.A.Sc., LEED AP Matthew Harris, M.Eng. Christopher Zabaneh, P.E., LEED AP Luka Matutinovic, P.Eng., LEED AP
- 4. Site vs Source Energy
- 6. metrics in practice V.S. CO2 Energy Green House Consumption Gas Emissions In Ontario, electricity emits 281 g eCO2/kWh natural gas emits 190 g eCO2/kWh
- 7. Utility Costs Electricity ~ $0.10 / kWh Gas ~ $0.30 / m3 ($0.03 / ekWh)
- 8. the details “Net-Zero” – Site? – Source? – Energy? – Emissions? – Net-annual net zero?
- 9. Design Principles What are you trying to achieve? •Comfort • Temperature • Humidity •Air Quality • Fresh Air • Pollutants
- 10. Occupant Comfort • Acoustical • Visual • Thermal • Physical • Psychological • Air Quality Clothing Expectation Source: http://www.passive-house.co.uk/
- 11. Typical office parameters Value 0.5 – 0.7 1.0 1.1 – 1.3 Activity Level Sleeping Seated Standing Long-sleeve shirt, Long-sleeve shirt, Clothing Level Pants, short shirt suit sweater And: Not in direct sunlight Air velocity below 40 fpm (otherwise drafty)
- 13. Thermal Comfort Envelope Contribution? Mechanical Contribution? 100% Electrical Contribution? 90% 80% 70% 60% 50% 40% SUMMER COMFORT WINTER 30% COMFORT 20% `10% ASHRAE 55 COMFORT CONDITIONS –PDD< 10%
- 14. Thermal Comfort: CFD Preliminary Design Airflow (velocity) Air temperature
- 15. Thermal Comfort: CFD Modified Design Airflow & Temperature
- 17. Filtration ASHRAE 52.1: Spot efficiency (old) ASHRAE 52.2: Particle Size (new) Efficiency MERV Value Application Types (52.1) (55.2) <20% 1-4 Residential Throwaway 20 - 35% 5-8 Commercial Pleated/Cartridge 80 - >95% 13-16 Hospitals / Labs Bag/Box 80- 90% 13 LEED Credit Bag Box N/A 17-20 Surgery / HEPA/ULPA Cleanrooms
- 18. Relevant Standards ASHRAE 62.1 – “most everything” ASHRAE 62.2 – just low-rise (Part 9) CSA – Hospitals Ontario Building Code Laboratories?
- 19. Where does ASHRAE 62.1 apply? • Any building intended for human occupancy • Except residential (< 3 storeys) • Regularly occupied and unoccupied spaces • Single- and multi-zone systems
- 20. ASHRAE 62.1 ASHRAE specifies two different ways to calculate minimum ventilation rates: Ventilation Rate Procedure • Required by most codes • LEED EQp1 requirement • Minimum OA ventilation rate OR Indoor Air Quality Procedure • Rarely used (not credited by LEED)
- 21. Ventilation Rate Procedure Minimum Outdoor Air Intake
- 22. Breathing zone OA flow (Vbz) Vbz = (Rp*Occupancy) + (Ra*Area) Table 6-1: ASHRAE 62.1
- 23. Zone Air Distribution Effectiveness Ceiling supply of cold Ceiling supply of warm air (typical VAV) air (VAV with reheat coils) effectiveness = 1 effectiveness = 0.8
- 24. Zone Air Distribution Effectiveness Displacement ventilation Under floor air distribution (floor supply of cool air) (mixing of air at 1.4m AFF) effectiveness = 1.2 effectiveness = 1
- 25. Modes of Ventilation Mixed Air Systems • VAV, CV, Induction Unit • Return air is mixed with outdoor air • Air handler provides ventilation and conditioning air • Fans and dampers are sized for cooling load typically Mixing Dampers • Outdoor air provided is based on the outdoor air fraction required at the “critical zone” ASHRAE Fundamentals – Chapter 27
- 26. Modes of Ventilation Decoupled Systems • DOAS or 100% OA • No mixing of return air with outdoor air • Stale air is exhaust from the space • Heating/cooling provided in the zone by radiant panels, heat pumps, or fancoils. • Outdoor air provided is sum of outdoor air required in all zones Modified from ASHRAE Fundamentals – Chapter 27
- 27. Modes of Ventilation Natural Ventilation • Ventilation is provided without the use of fans through operable windows or dampers • Process is driven by wind pressure or stack effect • Challenges with implementing in our climate • May see mixed mode systems that use natural ventilation when the OA temp is acceptable http://www.architecture.uwaterloo.ca/faculty_projects/terri/carbon-aia/case/global/global10.html
- 28. Monitoring and Controllability • CO2 sensors • Air delivery Monitoring • User controls
- 29. Ventilation Energy General Exhaust Sanitary Exhaust • Outdoor air required for BAS – Time of Day Schedule ventilation. • Outdoor air must usually be heated or cooled. • That requires energy. Outdoor Air Supply Air Return Air
- 30. Ventilation Energy Recovery • Exhaust air has energy in it (warmth in winter, “coolth” in summer) • Concept: Use that energy to temper the incoming outdoor air
- 31. Heat vs. Energy Recovery Common Terms: • “Heat Recovery Wheel” • “Heat Recovery Ventilator” • “Energy Recovery Wheel” • “Enthalpy Wheel” • “Energy Recovery Ventilator” • “Total Energy Wheel” • Change in DB is sensible heat (dry) • Change in WB is latent heat (wet)
- 32. Wheels • Pros: • Efficient • Both heat and humidity • Cons: • Big • Bulky (square)
- 33. Heat Pipes • Pros: • Simple • Robust • Cons: • “Dry heat” only • Bulky (side-by-side)
- 34. Other Options Glycol Loop • Pros: • Small (only adds 2 coils) • Simple • No cross contamination • Cons : • Requires a pump • Not as efficient – dry heat only Heat Recovery Ventilator • Self contained • Smaller air volumes • Sensible & latent heat
- 35. Reverse Flow Heat Exchangers
- 36. Considerations • Performance • Effectiveness/efficiency • “Dry/Sensible” vs “Total (Sensible + Latent)” • Cost-effectiveness • Size • Equipment • Ductwork • Configuration
- 37. What do we need HVAC for? Heating? Cooling? Humidifying and dehumidifying? Cleaning? Filtering? Ventilation?
- 38. How much HVAC and when? 35 30 25 Phoenix 20 15 balance point 10 5 Vancouver 0 Toronto -5 -10 J F M A M J J A S O N D
- 39. Toronto Climate Cooling 2% Heating 66%
- 40. Designing for low-energy Plug Loads Fa ns/ Pu Co m oli ps ng Hea t Lights
- 41. focus What’s important? Source: Halsall building performance database
- 42. focus What’s important? Ventilation Source: Halsall building performance database
- 43. focus On Ventilation 1. Window-to-wall ratio 2. Lighting power (fixtures and controls) 3. Window performance (highest U-value affordable) 4. Separate ventilation from heating and cooling (and low-energy hydronic heating and cooling) 5. Ventilation heat-recovery 6. Demand-controlled ventilation 7. Condensing heating boilers 8. Chiller efficiency (including chiller heat-recovery) 9. Wall and roof insulation (MNECB + R20 max) 10. Domestic hot water flow Adapted from Stephen Pope, NRCan (List prioritized for BC Lower Mainland)
- 44. Codes
- 46. Benchmarks
- 47. HVAC Systems Heating Ventilation Air Conditioning The purpose of an HVAC system is to control: • Temperature • Moisture (humidity) • Supply of outside air for ventilation • Filtration • Air movement in occupied spaces
- 48. HVAC Components t sst auu hha PLANT PLANT x EEx DISTRIBUTION S NE ZO Ventilation Ventilation
- 49. HVAC Methods
- 50. Heating Plant
- 51. Cooling Plant
- 55. Distribution
- 57. Ventilation
- 58. Exhaust
- 59. System Types –Single Zone Air Systems (Single Duct) Air is supplied to a single zone: • May or may not heat • Constant or variable volume • Constant or Variable temperature • Supply fan only, or return fan too • Cooling by DX or chilled water. • Heating by natural gas, or hot water • Provides ventilation • Simple controls
- 60. System Types –Multi Zone Air Systems (Single Duct) Air is supplied to multiple zones: • Generally cooling only • Constant (CV) or variable volume (VAV) • Constant or Variable temperature • Supply fan only, or return fan too • Cooling by DX or chilled water. • Heating by natural gas, or hot water • Provides Ventilation • Complicated Controls
- 61. System Types –Multi Zone Air Systems (Dual Duct) Air is supplied to multiple zones: • Heating and cooling by air • CV or VAV • Single fan or Dual fan (2 Supply Fans) • Used to avoid piping water • Cooling by DX or chilled water. • Heating by natural gas or hot water • Provides ventilation • Very Complicated Controls
- 62. System Types – Mixed Fan Coils / Heat Pumps / Induction Units Heating and Cooling is distributed to/from zone by water • Heating and cooling in zone by air • CV • Single fan • Needs ventilation ducted to space • Simple Controls
- 63. System Types – Water Heating and Cooling is distributed to/from zone by water • Heating / Cooling is done by water • Used typically with displacement ventilation but can be used with airside cooling • Radiant cooling requires tight controls on humidity • Controls can be fairly simple or very complex
- 64. Systems for a Building Type
- 65. Choosing a System Assessment, Selection, and Specification
- 66. Making Decisions What & When Concept Design •Zone Terminal •Distribution Method •Systems and Plants Schematic Design Detailed Design •Building Loads •Equipment Type, •Plant Location Location, and Size •Distribution Size and •Control Strategy Path •Coordination Tender •Contractors •Equipment
- 67. Making Decisions Challenges Concept Design •Mechanical / Energy Modeling not involved this early Schematic Design Detailed Design •Space Limitations •Service Space •Incomplete information •Coordination •Changes Tender •Controls
- 68. Considerations
- 72. Discussion
- 73. The Operational Reality How does it run? How is it used? Building Occupant operations space use Users account for 25% to 50% of all energy in a commercial office building. Building systems
- 74. Off is better than Efficient Provide Controllability – Lighting controls – Separate ventilation from heat/cool – Decentralized conditioning – Tenant engagement – Simple to Operate Manual override to turn ON
- 75. Low Carbon Energy What works well
- 76. Biomass Plant derived organic material Used as fuel source Direct or indirect combustion Continuous (unlike wind / solar) Fuel is cheap Delivery and storage can be an issue
- 77. Combined Heat and Power Electricity and Heat Fossil or biomass fuels Needs a heating base load year round for full efficiency Economics depend on utilities
- 78. Fuel Cells Direct energy conversion (no combustion) No moving parts Quiet Fuel flexibility Expensive Very early building applications
- 79. Ground Source Systems Heating and cooling system Usually combined with a electric heat pump system Effectiveness depends on ground conditions Requires a balanced heating / cooling load to be most efficient
- 80. Photovoltaics Converts sunlight directly to electricity Low maintenance Costs are dropping (less than $4/Watt) Limited by area, access and efficiency of cells
- 81. Solar Water Heating Proven technology Economic May require heat rejection in summer months
- 82. Solar Cooling Solar thermal energy Combined with absorption chiller Often combined with CHP Solution to “what to do with solar thermal in summer”
- 83. The Game Real-World Application of Low-Energy Design William Ding’s Novelty Bat Factory Head Office 40,000 sf two-story office building Cheap, inefficient design You’re hired as the Sustainability Consultant
- 84. Energy Modelling Wizard Game The Rules: Six Teams – Company A (3 teams) – Company B (3 teams) Each Team starts at different point: – Conceptual – Design Documents – Construction Documents
- 85. Base Building – 150 ekWh/m2 (50.2 kBTU/sf)
- 86. Energy Modelling Wizard Game To get a lower EUI…
- 87. Thank You!! ERohmann@halsall.com MHarris@halsall.com Questions? CZabaneh@halsall.com LMatutinovic@halsall.com
- 88. Energy Modelling Wizard Game Long east-west axis gives greater access to daylight with ease of glare control and reduced heat gain Long north-south axis creates greater exposure to low angle sun with more glare and heat gain N Building BUILDING