Energy Efficient Heating Ventilating and Air Conditioning

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Energy Efficient Heating Ventilating and Air
Conditioning
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Fundamental Equation

• Qf (A/R V pcp) (Tia Toa) Qint / Effh
• A area of envelope
• R thermal resistance of envelope
• V air flow rate
• pcp product of air density and specific heat
• Tia inside air temperature
• Toa outside air temperature
• Qint internal heat gain
• Effh efficiency of heating equipment

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Energy Saving Opportunities From Fundamental
Equation

• Increasing R
• Decreasing V
• Decreasing Tia
• Maximizing utilization of Qint
• Increasing Eh

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Inside-out Approach to HVAC Efficiency

• Minimize heating/cooling load
• Improve distribution system
• Improve efficiency of heating/cooling plant

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Increasing R Insulation
Diminishing return of increasing
insulation Adding R10 hr-ft2-F/Btu and (Tia
Toa) 35 F
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Increasing R Insulation

• Insulate walls with spray on cellulose or
  closed-cell foam

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Increasing R Insulation

• Cover single-pane glass with double-wall
  polycarbonate sheets to reduce conduction and
  infiltration losses.

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Replace Old Dock Doors
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Replace Dark Roof with White Roof

• White roofs reflect sunlight and reduce air
  conditioning load

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Reduce Outside Air Flow

• Air leaking into/out of building
• Typically largest single heating/cooling load
• 1 air changes per hour in small buildings
• Up to 8 air changes per hour in factories
• Driven by
• Temperature difference and wind in small
  buildings
• Ventilation and combustion loads in factories
• Quantify/identify by
• Blower door test and IR camera
• Manual search during cold / windy weather
• Reduce by
• Sealing leaks around windows, doors and
  foundations in small buildings
• Balancing air pressure in plants and large
  buildings

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Reduce Outside Air FlowClose Doors and Openings

• Install garage-door openers on lift-trucks to
  close shipping doors!

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Reduce Outside Air FlowClose Doors and Openings

• Install garage-door openers on lift-trucks
• Observation Heating energy varies by 3X at same
  temp!
• Discovery Didnt close shipping doors!

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Reduce Outside Air Flow Turn Off Dust
Collectors When Not In Use
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Return Scrap Paper Collector Exhaust to Plant

• Clean air can be returned to plant

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Install VFDs on Vent Hoods
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Introduce Make-up Air Near Exhaust Air Locations
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Introduce Make-up Air Near Exhaust Air Locations
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Supply Outside Air to Scrap Transport System
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Install Louvers in High Section of Furnace
Building
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Install Louvers in High Section of Furnace
Building
Savings 19,000 mmBtu/yr
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Reverse Direction of Exhaust Fan during Winter

• Savings 300 mmBtu/yr

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Case Study Reduce Winter Ventilation and Balance
Plant Air Pressure
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Case Study Reduce Winter Ventilation and Balance
Plant Air Pressure
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Case Study Reduce Winter Ventilation and Balance
Plant Air Pressure
Weather-adjusted baseline gas use 6,117
mmBtu Weather-adjusted savings 3,137
mmBtu Reduction 51.
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Reduce Tia
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Use Programmable Thermostats

• Lower/increase interior set-point temp during
  unoccupied periods
• Important because heating/cooling load
  proportional to (Tia Toa)
• Example If Toa 50 F, then reducing Tia from
  70 F to 60 F decreases heating load by 50
• However, thermal mass limits temperature drop
  and reduces savings

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Deliver Heat Effectively

• Problem
• Warm air pulled out of facility by exhaust fans
  or openings
• Excess temperature stratification (warm air near
  ceiling)
• Solution
• Install radiant heaters in high ventilation areas

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Deliver Heat Effectively

• Problems
• Excess temperature stratification
• Solution
• Install destratification fans

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Deliver Heat EffectivelyDeficit Made up by
Infiltration
Negative pressure heating penalty drawing and
heating excess leakage air.
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Deliver Heat Effectively Employ Differential
Pressure Control

• Manometer measures DP between inside and outside,
  and adjusts air flow of MAU
• Good choice if ventilation requirements change
  frequently
• Paint booths
• Large combustion air demands

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Distribute Outside Air Throughout Plant
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100 Efficient Make-up Air Unit
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80 Efficient Unit Heater
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If Dont Need Outside Air, Use Unit Heaters

• Unit heaters and air rotation units
• 80 efficient
• Recirculate inside air
• Make-up air units
• 100 efficient
• Supply outside air
• Selection
• If dont need outside air, use unit heaters to
  reduce heating load
• If need outside air, use makeup air units for
  high efficiency

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If Need Outside Air, Use Makeup Air Units

• Unit heaters and air rotation units
• 80 efficient
• Recirculate inside air
• Make-up air units
• 100 efficient
• Supply outside air
• Selection
• If dont need outside air, use unit heaters to
  reduce heating load
• If need outside air, use makeup air units for
  high efficiency

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Use economizer if year-round cooling

• Economizer malfunction identified with billing
  analysis

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Replace Old Cooling Units with High Efficiency
Units

• Most rooftop units SEER 10 Btu/Wh
• New rooftop units SEER 12 Btu/Wh

• Example
• Savings Qload x (1/SEER1 1/SEER2)
• Savings 100,000 Btu/h x (1/10 1/12) 1.7 kW
• Savings 1.7 kW x 1,000 hr/yr x 0.10 /kWh
  170 /yr

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Use Outside Air Requirement to Select Unit
Heater or MAU

• Unit heaters and air rotation units
• 80 efficient
• Recirculate inside air
• Make-up air units
• 100 efficient
• Supply outside air
• Selection
• If dont need outside air, use unit heaters to
  reduce heating load
• If need outside air, use makeup air units for
  high efficiency