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Building Energy Fundementals_Halsall

Building Energy Fundementals_Halsall



Halsall Engineers presentation on building energy fundamentals for the Toronto CSBA 2013 course

Halsall Engineers presentation on building energy fundamentals for the Toronto CSBA 2013 course



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    Building Energy Fundementals_Halsall Building Energy Fundementals_Halsall Presentation Transcript

    • G SBA Course Unit 3Mechanical Systems November 24, 2012
    • Agenda1. Intro to Energy2. Design Principles3. HVAC Systems4. Controls/Commissioning/Operations5. The Game
    • Who we areErich Rohmann, B.A.Sc., LEED APMatthew Harris, M.Eng.Christopher Zabaneh, P.E., LEED APLuka Matutinovic, P.Eng., LEED AP
    • Site vs Source Energy
    • Energy Metrics
    • metrics in practice V.S. CO2 Energy Green HouseConsumption Gas Emissions In Ontario, electricity emits 281 g eCO2/kWh natural gas emits 190 g eCO2/kWh
    • Utility CostsElectricity ~ $0.10 / kWh Gas ~ $0.30 / m3 ($0.03 / ekWh)
    • the details“Net-Zero” – Site? – Source? – Energy? – Emissions? – Net-annual net zero?
    • Design PrinciplesWhat are you trying to achieve?•Comfort • Temperature • Humidity•Air Quality • Fresh Air • Pollutants
    • Occupant Comfort• Acoustical• Visual• Thermal• Physical• Psychological• Air Quality Clothing Expectation Source: http://www.passive-house.co.uk/
    • 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 sweaterAnd: Not in direct sunlight Air velocity below 40 fpm (otherwise drafty)
    • Naturally Ventilated Buildings
    • 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%
    • Thermal Comfort: CFDPreliminary Design Airflow (velocity) Air temperature
    • Thermal Comfort: CFDModified Design Airflow & Temperature
    • Indoor Air Quality
    • FiltrationASHRAE 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
    • Relevant StandardsASHRAE 62.1 – “most everything”ASHRAE 62.2 – just low-rise (Part 9)CSA – HospitalsOntario Building CodeLaboratories?
    • 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
    • ASHRAE 62.1ASHRAE specifies two different ways to calculate minimum ventilation rates:Ventilation Rate Procedure • Required by most codes • LEED EQp1 requirement • Minimum OA ventilation rate ORIndoor Air Quality Procedure • Rarely used (not credited by LEED)
    • Ventilation Rate Procedure Minimum Outdoor Air Intake
    • Breathing zone OA flow (Vbz)Vbz = (Rp*Occupancy) + (Ra*Area) Table 6-1: ASHRAE 62.1
    • Zone Air Distribution EffectivenessCeiling supply of cold Ceiling supply of warmair (typical VAV) air (VAV with reheat coils)effectiveness = 1 effectiveness = 0.8
    • Zone Air Distribution EffectivenessDisplacement ventilation Under floor air distribution(floor supply of cool air) (mixing of air at 1.4m AFF)effectiveness = 1.2 effectiveness = 1
    • 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
    • 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 zonesModified from ASHRAE Fundamentals – Chapter 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 acceptablehttp://www.architecture.uwaterloo.ca/faculty_projects/terri/carbon-aia/case/global/global10.html
    • Monitoring and Controllability • CO2 sensors • Air delivery Monitoring • User controls
    • Ventilation EnergyGeneral 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
    • 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
    • Heat vs. Energy RecoveryCommon 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)
    • Wheels• Pros: • Efficient • Both heat and humidity• Cons: • Big • Bulky (square)
    • Heat Pipes• Pros: • Simple • Robust• Cons: • “Dry heat” only • Bulky (side-by-side)
    • Other Options Glycol Loop • Pros: • Small (only adds 2 coils) • Simple • No cross contamination • Cons : • Requires a pump • Not as efficient – dry heat onlyHeat Recovery Ventilator• Self contained• Smaller air volumes• Sensible & latent heat
    • Reverse Flow Heat Exchangers
    • Considerations• Performance • Effectiveness/efficiency • “Dry/Sensible” vs “Total (Sensible + Latent)”• Cost-effectiveness• Size • Equipment • Ductwork • Configuration
    • What do we need HVAC for?Heating?Cooling?Humidifying and dehumidifying?Cleaning?Filtering?Ventilation?
    • How much HVAC and when?35                        30                        25                   Phoenix      20                        15                         balance point10                         5                        Vancouver 0                        Toronto -5                        -10                         J F M A M J J A S O N D
    • Toronto Climate Cooling 2%Heating 66%
    • Designing for low-energy Plug Loads Fa ns/ Pu Co m oli ps ng Hea t Lights
    • focus What’s important?Source: Halsall building performance database
    • focus What’s important? VentilationSource: Halsall building performance database
    • 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 flowAdapted from Stephen Pope, NRCan(List prioritized for BC Lower Mainland)
    • Codes
    • Standards / Guidelines
    • Benchmarks
    • HVAC SystemsHeating 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
    • HVAC Components t sst auu hhaPLANTPLANT x EEx DISTRIBUTION S NE ZO Ventilation Ventilation
    • HVAC Methods
    • Heating Plant
    • Cooling Plant
    • Geo-exchange Field
    • Air-Handling Unit
    • Distribution
    • Zone Terminal Units
    • Ventilation
    • Exhaust
    • 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
    • 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
    • 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
    • System Types – Mixed Fan Coils / Heat Pumps / Induction UnitsHeating 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
    • System Types – WaterHeating 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
    • Systems for a Building Type
    • Choosing a SystemAssessment, Selection, and Specification
    • Making DecisionsWhat & 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
    • Making DecisionsChallenges Concept Design •Mechanical / Energy Modeling not involved this early Schematic Design Detailed Design •Space Limitations •Service Space •Incomplete information •Coordination •Changes Tender •Controls
    • Considerations
    • Project TeamsContractorCommissioning
    • Discussion
    • The Operational Reality How does it run? How is it used? Building Occupantoperations space use Users account for 25% to 50% of all energy in a commercial office building. Building systems
    • 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
    • Low Carbon Energy What works well
    • BiomassPlant derived organic materialUsed as fuel sourceDirect or indirect combustionContinuous (unlike wind / solar)Fuel is cheapDelivery and storage can be an issue
    • Combined Heat and PowerElectricity and HeatFossil or biomass fuelsNeeds a heating base load year round for full efficiencyEconomics depend on utilities
    • Fuel CellsDirect energy conversion (no combustion)No moving partsQuietFuel flexibilityExpensiveVery early building applications
    • Ground Source SystemsHeating and cooling systemUsually combined with a electric heat pump systemEffectiveness depends on ground conditionsRequires a balanced heating / cooling load to be most efficient
    • PhotovoltaicsConverts sunlight directly to electricityLow maintenanceCosts are dropping (less than $4/Watt)Limited by area, access and efficiency of cells
    • Solar Water HeatingProven technologyEconomicMay require heat rejection in summer months
    • Solar CoolingSolar thermal energyCombined with absorption chillerOften combined with CHPSolution to “what to do with solar thermal in summer”
    • The GameReal-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
    • 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
    • Base Building – 150 ekWh/m2 (50.2 kBTU/sf)
    • Energy Modelling Wizard GameTo get a lower EUI…
    • Thank You!!ERohmann@halsall.comMHarris@halsall.com Questions?CZabaneh@halsall.comLMatutinovic@halsall.com
    • Energy Modelling Wizard GameLong east-west axis gives greater access to daylight with ease of glare control and reduced heat gainLong north-south axis creates greater exposure to low angle sun with more glare and heat gain N Building BUILDING