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

[email protected]

www.EnergyBooks.com

http://www.ics.li/CFDOCS/cmsout/admin/i_folge.cfm?meID=1&Lang=1&GroupID=69




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




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.





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





These deficiencies of multiple-zoneair handling systems are INHERENT.

They cannot be fixed.

So, multiple-zone systems must be

ABANDONED.





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.





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.





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





INTRODUCING

OPTIMIZED-FUNCTION DESIGN

IMPROVING DESIGN PRACTICE





OPTIMIZED-FUNCTION DESIGN

addresses every function

of each application

in an optimum manner.





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.






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.







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!






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.










3. For each zone, select equipmentto fulfill each function optimally.

















EQUIPMENT CONSOLIDATION(One Unit is Needed for Each Zone)

(Filters, humidifiers, and controls are omitted for clarity.)





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.














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




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





FIXING THE EQUIPMENT

OPTIMIZING

DEHUMIDIFICATIONIN SINGLE-ZONE SYSTEMS





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%





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





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.





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).









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.





REHEAT in a HYDRONIC Conditioning Unit





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





OTHER DEHUMIDIFICATION IMPROVEMENTS(not explicitly single-zone issues)

Dehumidify where moisture concentration is greatest.

Include latent heat recovery. Eliminate moisture retention on cooling coils.



















FIXING THE EQUIPMENT

OPTIMIZING

VENTILATIONIN SINGLE-ZONE SYSTEMS





NOTORIOUS VENTILATION DEFECTSIN SINGLE-ZONE SYSTEMS

Inability to regulate outside air intake

accurately.

Air infiltration into spaces and equipment

during idle periods.





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.





PREVENTION OF OUTSIDE AIR LEAKAGE

Install HERMETIC dampers for ISOLATION.





OTHER SINGLE-ZONE VENTILATION IMPROVEMENTS

Optimize outside air economizer cycle.

Incorporate exhaust air heat recovery.





OTHER SINGLE-ZONE VENTILATION IMPROVEMENTS

Optimize outside air economizer cycle.

Incorporate exhaust air heat recovery.





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.





THE FINAL

REFINEMENTSIN OPTIMIZED-FUNCTION SYSTEMS

MINIMIZE AIR MOVEMENT ENERGY

ELIMINATE ALL HEALTH HAZARDS






Abolish control dampers (another reason).

Bypass idle coils.






Abolish control dampers (another reason).

Bypass idle coils.






Sterilize air handling equipment continuously.

Include appropriate filtering, biocides, etc.

to eliminate hazards from the air stream.






Sterilize air handling equipment continuously.

Include appropriate filtering, biocides, etc.

to eliminate hazards from the air stream.





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.





ONWARD TO THE FUTURE!

Design Your HVAC for this Century,

Not the Last One

The Survival of Civilization Depends on It





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


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