Optimized HVAC for the 21st Century

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Optimized HVAC for the 21st Century

• Donald R. Wulfinghoff, P.E.
• Wulfinghoff Energy Services, Inc.
• Wheaton, Maryland USA
• 301 946 1196
• DW_at_EnergyBooks.com
• www.EnergyBooks.com

www.clima2005.ch
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A REVOLUTION IN 45 MINUTES

• Contemporary HVAC equipment and design practices
  are obsolete. They cannot satisfy the stringent
  requirements of the 21st Century for

• ENERGY EFFICIENCY
• HEALTH
• RESISTANCE TO TERRORISM

• The essential changes can be made quickly.
• Here is how to do it.

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THE LOGIC

1. HVAC systems are either multiple-zone or
   single-zone.
2. Multiple-zone air handling systems inherently
   cannot perform all HVAC functions and operate
   efficiently. So, they must be abandoned.
3. Single-zone systems can satisfy all HVAC
   functions efficiently.
4. But, contemporary single-zone HVAC equipment
   performs poorly because of flaws in design and
   equipment.
5. We will solve the design problem by introducing
   a new approach to design that optimizes every
   function required by the application.
6. We will solve the equipment problem by showing
   how to correct all the flaws of contemporary
   single-zone equipment.

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Multiple-Zone Air Handling SystemsInherently
Cannot Satisfy All HVAC Functions

1. Temperature control of individual spaces forces
   a 3-way compromise between COMFORT, VENTILATION,
   and ENERGY EFFICIENCY.
2. All multiple-zone systems inherently have?
   INEFFICIENT and/or INADEQUATE VENTILATION?
   HEALTH HAZARDS? FIRE HAZARD? AIR TRANSPORT
   LOSSES? AIR LEAKAGE into Idle Spaces and
   Equipment? And Now, VULNERABILITY TO TERRORISM

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These deficiencies of multiple-zone air handling
systems are INHERENT. They cannot be
fixed.So, multiple-zone systems must be
ABANDONED.
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Footnote VAV is a Failed Experiment

• Ventilation is radically worse than with
  constant-volume systems.
• Improving comfort and ventilation requires a
  return to reheat.
• Discomfort is endemic.
• Combining heating and cooling is problematic.

An Interesting Trend Fan-powered VAV terminals
are an evolution toward single-zone systems.
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So, the optimized HVAC of the 21st century
will use SINGLE-ZONE systems exclusively.

• They can avoid all conflicts between energy
  efficiency and the HVAC functions.
• They can avoid all health hazards.
• They cover smaller areas, limiting the spread of
  fire and noxious agents.

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Then, WHY are SINGLE-ZONE Systems Not the Primary
Choice for HVAC Today?

• DESIGN DEFICIENCIES Designers neglect to tailor
  single-zone systems to the functions needed by
  the application. (Multiple-zone systems tend to
  be multi-functional, although inefficient.)  
• EQUIPMENT DEFICIENCIES
• Lack of rational humidity control
• Ineffective control of ventilation
• Failure to exploit opportunities for efficiency
• Generally poor quality

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INTRODUCINGOPTIMIZED-FUNCTION DESIGN
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OPTIMIZED-FUNCTION DESIGNaddresses every
function of each application in an optimum
manner.
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The Steps of OPTIMIZED-FUNCTION HVAC Design

1. Define all the HVAC functions that are needed
   for each application in the facility.
2. Define the spatial zones that correspond to each
   function. (Zones may differ for different
   functions.)
3. For each zone, select equipment to fulfill each
   function optimally.
4. Consolidate the equipment.
5. Optimize the control of the equipment.

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The Steps of OPTIMIZED-FUNCTION HVAC Design

1. Define all the HVAC functions that are needed for
   each application in the facility.
2. Define the spatial zones that correspond to each
   function. (Zones may differ for different
   functions.)
3. For each zone, select equipment to fulfill each
   function optimally.
4. Consolidate the equipment.
5. Optimize the control of the equipment.

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The Common Functions of HVAC(More Than You
Realize!)
FUNCTIONS NOT INVOLVING O.A. FUNCTIONS INVOLVING O.A.
Raise Space Temperature Select Cleanest Outside Air
Lower Space Temperature Use Outside Air for Cooling
Raise Space Humidity Raise Humidity of Outside Air
Lower Space Humidity Lower Humidity of Outside Air
Distribute Conditioned Air Control Pressure Relative to Outside
Circulate Air for Comfort Remove Outside Air Pollutants
Remove Space Air Pollutants Recover Sensible Heat from Exhaust
Control Pressure Between Spaces Recover Latent Heat from Exhaust
Limit Spread of Fire Prevent Intake of Noxious Agents
Limit Spread of Noxious Agents
AND perform all these functions with minimum
energy!
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The Steps of OPTIMIZED-FUNCTION HVAC Design

1. Define all the HVAC functions that are needed for
   each application in the facility.
2. Define the spatial zones that correspond to each
   function. (Zones may differ for different
   functions.)
3. For each zone, select equipment to fulfill each
   function optimally.
4. Consolidate the equipment.
5. Optimize the control of the equipment.

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The Steps of OPTIMIZED-FUNCTION HVAC Design

1. Define all the HVAC functions that are needed for
   each application in the facility.
2. Define the spatial zones that correspond to each
   function. (Zones may differ for different
   functions.)
3. For each zone, select equipment to fulfill each
   function optimally.
4. Consolidate the equipment.
5. Optimize the control of the equipment.

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The Steps of OPTIMIZED-FUNCTION HVAC Design

1. Define all the HVAC functions that are needed for
   each application in the facility.
2. Define the spatial zones that correspond to each
   function. (Zones may differ for different
   functions.)
3. For each zone, select equipment to fulfill each
   function optimally.
4. Consolidate the equipment.
5. Optimize the control of the equipment.

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EQUIPMENT CONSOLIDATION(One Unit is Needed for
Each Zone)
(Filters, humidifiers, and controls are omitted
for clarity.)
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Fulfilling all the functions of the application
usually does NOT require a potpourri of
equipment.A high degree of EQUIPMENT
CONSOLIDATIONis possible. A high degree of
STANDARDIZATION is possible.
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The Steps of OPTIMIZED-FUNCTION HVAC Design

1. Define all the HVAC functions that are needed for
   each application in the facility.
2. Define the spatial zones that correspond to each
   function. (Zones may differ for different
   functions.)
3. For each zone, select equipment to fulfill each
   function optimally.
4. Consolidate the equipment.
5. Optimize the control of the equipment.

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Provide OPTIMUM CONTROL for ALL Conditions
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ECONOMICS of Optimized-Function HVAC
COST ISSUE(in order of cost) PERFORMANCE (Relative to Multiple-Zone Systems)
Human Productivity Health Major Improvement
Energy Cost Much Lower
Loss of Rentable Space Much Less
Equipment Cost About Same
Insurance Against Hazards Much Less Expensive
Maintenance More Expensive, but Minor
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FIXING THE EQUIPMENT

• OPTIMIZINGDEHUMIDIFICATIONIN SINGLE-ZONE
  SYSTEMS

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ABOLISH CHEAP MOTEL SYNDROME
24 C, 40
11 C, 100
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The Solution is REHEAT
32 C, 90
24 C, 40
11 C, 100
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Isnt Reheat EXPENSIVE?Not in single-zone
systems. Its FREE.

• Reheat is expensive in multiple-zone systems
  because it is used for temperature control in
  addition to humidity control.
• But, single-zone systems do not need reheat for
  space temperature control.
• A cooling system always rejects enough heat to
  provide free reheat for humidity control.

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REHEAT for humidity control in single-zone
systems is FREE because it can be done entirely
with REJECTED HEAT

1. Heat rejected in any cooling process always
   exceeds the cooling load.
2. Reheat needed for dehumidification is always
   less than the cooling load.
3. Single-zone systems do not need reheat for other
   functions (temperature control).

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Reheating with condenser heat is the most
efficient method of dehumidification by cooling
that is possible

• It INCREASES THE EFFICIENCY of the cooling
  equipment.
• It is even more efficient than using renewable
  energy sources for reheat.

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REHEAT in a HYDRONIC Conditioning Unit
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DESIGN CHALLENGES WHEN USING REJECTED HEATIN
HYDRONIC SYSTEMS

• Reheat coils must be enhanced to exploit the LOW
  TEMPERATURE of rejected heat (typically ca. 50
  C), which is further reduced by hydronic heat
  transfer.
• Condenser cooling water has low energy density,
  so it is important to MINIMIZE HEAT LOSS and
  PUMPING ENERGY. Otherwise, pumping energy will
  add significant cost to dehumidification.

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OTHER DEHUMIDIFICATION IMPROVEMENTS(not
explicitly single-zone issues)

• Dehumidify where moisture concentration is
  greatest.
• Include latent heat recovery.
• Eliminate moisture retention on cooling coils.

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OTHER DEHUMIDIFICATION IMPROVEMENTS(not
explicitly single-zone issues)

• Dehumidify where moisture concentration is
  greatest.
• Include latent heat recovery.
• Eliminate moisture retention on cooling coils.

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OTHER DEHUMIDIFICATION IMPROVEMENTS(not
explicitly single-zone issues)

• Dehumidify where moisture concentration is
  greatest.
• Include latent heat recovery.
• Eliminate moisture retention on cooling coils.

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FIXING THE EQUIPMENT

• OPTIMIZINGVENTILATIONIN SINGLE-ZONE SYSTEMS

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NOTORIOUS VENTILATION DEFECTSIN SINGLE-ZONE
SYSTEMS

• Inability to regulate outside air intake
  accurately.
• Air infiltration into spaces and equipment
  during idle periods.

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ACCURATE CONTROL OF OUTSIDE AIR

• ABOLISH CONTROL DAMPERS! This requires 2 steps

1. Control ventilation air intake with
   variable-speed fans.
2. Control fans with air flow monitoring.

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PREVENTION OF OUTSIDE AIR LEAKAGE

• Install HERMETIC dampers for ISOLATION.

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OTHER SINGLE-ZONE VENTILATION IMPROVEMENTS

• Optimize outside air economizer cycle.
• Incorporate exhaust air heat recovery.

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OTHER SINGLE-ZONE VENTILATION IMPROVEMENTS

• Optimize outside air economizer cycle.
• Incorporate exhaust air heat recovery.

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IMPROVE VENTILATION SYSTEM DESIGNOUTSIDE THE
EQUIPMENT BOXES (not explicitly single-zone
issues)

• Improve the efficiency of air distribution to
  the occupants.
• Control ventilation rate in response to need.
• Select the best air intake source.

• Cleanest air
• Isolated from wind pressure
• Inaccessible to mischief
• Warmest or coolest air source, depending on
  requirement

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THE FINALREFINEMENTSIN OPTIMIZED-FUNCTION
SYSTEMS

• MINIMIZE AIR MOVEMENT ENERGY
• ELIMINATE ALL HEALTH HAZARDS

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MINIMIZE AIR MOVEMENT ENERGY

• Abolish control dampers (another reason).
• Bypass idle coils.

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MINIMIZE AIR MOVEMENT ENERGY

• Abolish control dampers (another reason).
• Bypass idle coils.

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ELIMINATE ALL HEALTH HAZARDS

• Sterilize air handling equipment continuously.
• Include appropriate filtering, biocides, etc. to
  eliminate hazards from the air stream.

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ELIMINATE ALL HEALTH HAZARDS

• Sterilize air handling equipment continuously.
• Include appropriate filtering, biocides, etc. to
  eliminate hazards from the air stream.

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EQUIPMENT MANUFACTURING ISSUES

• Optimized HVAC equipment is easy to manufacture,
  not significantly more difficult than
  contemporary equipment.
• Existing equipment serves as prototypes for
  optimized equipment.
• Much existing equipment can be used in optimized
  systems as it presently exists.

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ONWARD TO THE FUTURE!

• Design Your HVAC for this Century, Not the Last
  One
• The Survival of Civilization Depends on It

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Let the discussion continue

• Donald R. Wulfinghoff, P.E.Wulfinghoff Energy
  Services, Inc.Wheaton, Maryland USA301 946
  1196 DW_at_EnergyBooks.comwww.EnergyBooks.com
• In LAUSANNE Tulip Inn