clima 2005 wulfinghoff plenary slides
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Clima 2005 Lausanne | Solothurnstrasse 13 | CH-3322 Schönbühl | Switzerland
8th
REHVA World Congress | Phone +41 (31) 852 13 00 | Fax +41 (31) 852 13 01 | Email: [email protected]
www.clima2005.ch
Optimized HVAC for the 21st Century
Donald R. Wulfinghoff, P.E.
Wulfinghoff Energy Services, Inc.Wheaton, Maryland USA
301 – 946 – 1196
www.EnergyBooks.com
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A REVOLUTION IN 45 MINUTES
Contemporary HVAC equipment anddesign practices are obsolete. Theycannot satisfy the stringent requirementsof the 21st Century for:
The essential changes can be made quickly.
Here is how to do it.
ENERGY EFFICIENCY HEALTH
RESISTANCE TO TERRORISM
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THE LOGIC
1. HVAC systems are either multiple-zone or single-zone.
2. Multiple-zone air handling systems inherent ly cannot perform all HVAC functions and operate efficiently.So, they must be abandoned.
3. Single-zone systems can satisfy all HVAC functionsefficiently.
4. But, contemporary single-zone HVAC equipment performspoorly because of flaws in design and equipment .
5. We will solve the design problem by introducinga new approach to design that optimizes every functionrequired by the application.
6. We will solve the equipment problem by showing how tocorrect all the flaws of contemporary single-zone equipment.
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Multiple-Zone Air Handling Systems
Inherently 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-zoneair 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 withconstant-volume systems.
Improving comfort and ventilation requiresa return to reheat.
Discomfort is endemic.
Combining heating and cooling is problematic.
An Interesting Trend: Fan-powered VAV terminalsare an evolution toward single-zone systems.
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So, … the optimized HVAC of the
21st
century will use SINGLE-ZONEsystems exclusively.
They can avoid all conflicts between
energy efficiency and the HVACfunctions.
They can avoid all health hazards.
They cover smaller areas, limiting thespread 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 func t ions needed bythe 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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INTRODUCING
OPTIMIZED-FUNCTION DESIGN
IMPROVING DESIGN PRACTICE
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OPTIMIZED-FUNCTION DESIGN
addresses 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 areneeded for each application in thefacility.
2. Define the spatial zones that correspond to eachfunction. (Zones may differ for different functions.)
3. For each zone, select equipment to fulfill eachfunction 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 OutsideCirculate 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 eachfunction 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 eachfunction. (Zones may differ for different functions.)
3. For each zone, select equipmentto 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 eachfunction. (Zones may differ for different functions.)
3. For each zone, select equipmentto 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 applicationusually does NOT require a potpourri of
equipment.
A high degree of EQUIPMENT CONSOLIDATION
is possible.
A high degree of STANDARDIZATIONis 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 eachfunction. (Zones may differ for different functions.)
3. For each zone, select equipmentto fulfill each function optimally.
4. Consolidate the equipment.
5. Optimize the control of the equipment.
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Conditioning Mode F1 F2 C1 C2 H D1 D2 D3 D4 D5 D6 D7
Heating: all conditions O O X X O O O X O X O X
Mechanical cooling: no dehumidification
needed O O O X X X O O O X O X
Mechanical cooling: low outside humidity,inside moisture requires dehumidification
O O O X O X X X O X O X
Mechanical cooling: outside humidityrequires dehumidification
O O O O O X X X O O X X
Economizer cooling: mechanical coolingnot needed
O X X X X O X O X X X O
Economizer cooling: supplementalmechanical cooling required, but notdehumidification
O X O X X X O O X X X O
Economizer cooling: supplementalmechanical cooling and dehumidification
O X O X O X X X X X X O
Purge Cycle (for cooling or air cleaning) O X X X X O X O X X X O
Zone Shutdown X X X X X X X X X X X X
Legend: F – Fan. All fans are variable-speed.C – Cooling coilH – Heating coilD – Damper. All dampers are 2-position (fully open or fully closed)R – Heat recovery (coil or heat exchanger)A – Air flow sensor O – “on” (for fans and coils) or “open” (for dampers)
X – “off” (for fans and coils) or “closed” (for dampers)
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
OPTIMIZING
DEHUMIDIFICATIONIN SINGLE-ZONE SYSTEMS
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ABOLISH
“CHEAP MOTEL SYNDROME”
24 C, 40%
11 C, 100%
D R Y BU LB T EM PE R AT U R E ( F )
80
40
40
60
W e t
B u l b ( F )
50
50
60
70
70
4 0 %
80 90 100 120
2 0 %
8 0 %
6 0 %
90
.004
.016
.012
.008
H U M I D
I T Y R A T I O
( L b v / L
b a )
.028
.024
.020
32 C, 90%
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The Solution is REHEAT
24 C, 40%
11 C, 100%
32 C, 90%
D R Y BU LB T EM PE R AT U R E ( F )
80
40
40
60
W e t
B u l b ( F )
50
50
60
70
70
4 0 %
80 90 100 120
2 0 %
8 0 %
6 0 %
90
.004
.016
.012
.008
H U M I D
I T Y R A T I O
( L b v / L
b a )
.028
.024
.020
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Isn’t Reheat EXPENSIVE?
Not in single-zone systems. It’s FREE.
Reheat is expensive in mult ip le-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 mostefficient 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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Reheat coils must be enhanced to exploit the
LOW TEMPERATURE of rejected heat
(typically ca. 50 C), which is further reducedby hydronic heat transfer.
Condenser cooling water has low energy density,
so it is important to MINIMIZE HEAT LOSS and
PUMPING ENERGY. Otherwise, pumping energywill add significant cost to dehumidification.
DESIGN CHALLENGES
WHEN USING REJECTED HEAT
IN HYDRONIC SYSTEMS
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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
OPTIMIZING
VENTILATIONIN 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 DESIGN
OUTSIDE THE EQUIPMENT BOXES
(not explicitly single-zone issues)
Cleanest air
Isolated from wind pressure
Inaccessible to mischief Warmest or coolest air source,
depending on requirement
Improve the efficiency of air distributionto the occupants.
Control ventilation rate in response to need.
Select the best air intake source.
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THE FINAL
REFINEMENTSIN 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 USA
301 – 946 – 1196 [email protected]
www.EnergyBooks.com
In LAUSANNE: Tulip Inn