Asia Pacific Research Initiative for Sustainable Energy Systems
2013 (APRISES13)
Office of Naval Research Grant Award Number N00014-14-1-0054
DESICCANT DEHUMIDIFICATION APPLICATIONS IN HAWAII
PHASE 1 PROJECT SUMMARY
Task 7
Prepared For Hawaii Natural Energy Institute
Prepared By Sustainable Design & Consulting LLC & HNEI
November 2017
DESICCANT DEHUMIDIFICATION TO SUPPORT ENERGY EFFICIENT SPACE CONDITIONING
SYSTEMS FOR HAWAII
Project Deliverable 5:
“PROJECT SUMMARY REPORT AND PRESENTATION
THE GROWING INDOOR HUMIDITY CHALLENGES OF
BUILDINGS, AND STRATEGIES TO SOLVE THEM”
November 27, 2017
FINAL
Sustainable Design & Consulting LLC
Prepared by:
Manfred J. Zapka, PhD, PE James Maskrey, MEP, MBA
Prepared for
Hawaii Natural Energy Institute
RCUH P.O. #Z10143891
Project Phase 1: Design Study and Project Site Selection
Nov. 27, 2017
DESICCANT DEH
UMIDIFICATION TO SUPPORT EN
ERGY
EFFICIENT SPACE CONDITIONING SYSTEM
S FO
R HAWAII
"PROJECT SU
MMARY REP
ORT AND PRESEN
TATION; TH
E GROWING IN
DOOR
HUMIDITY CHALLEN
GES OF BUILDINGS, AND STR
ATEGIES TO
SOLVE TH
EM”
Sustainable Design &
Consulting LLC
5.5.Deliverable
FINAL Nov. 27, 2017
DESICCANT DEH
UMIDIFICATION TO SUPPORT EN
ERGY
EFFICIENT SPACE CONDITIONING SYSTEM
S FO
R HAWAII
"PROJECT SU
MMARY REP
ORT AND PRESEN
TATION; TH
E GROWING IN
DOOR
HUMIDITY CHALLEN
GES OF BUILDINGS, AND STR
ATEGIES TO
SOLVE TH
EM”
Sustainable Design &
Consulting LLC
5.5.Deliverable
FINAL
DESICCANT DEHUMIDIFICATION TO SUPPORT ENERGY EFFICIENT SPACE CONDITIONING SYSTEMS FOR HAWAII
PROJECT PHASE 1: DESIGN STUDY AND PROJECT SITE SELECTION
PROJECT DELIVERABLE NO. 5
PROJECT SUMMARY REPORT AND PRESENTATION
THE GROWING INDOOR HUMIDITY CHALLENGES OF BUILDINGS,
AND STRATEGIES TO SOLVE THEM
Preparing a pilot installation in Hawaii of using Liquid desiccant dehumidification in HVAC to control indoor humidity problems and improve indoor air quality, while saving energy.
A Summary Report of the Project Work and Illustrated Presentation
FINAL
Prepared for
Hawaii Natural Energy Institute
RCUH P.O. #Z10143891
November 27, 2017
Prepared by:
Manfred J. Zapka, PhD, PE (1)
James Maskrey, MEP, MBA, Project Manager (2)
(1) Sustainable Design & Consulting LLC, Honolulu, Hawaii
(2) Hawaii Natural Energy Institute Honolulu, Hawaii
ACKNOWLEDGEMENTS
This project is funded by the Hawaii Natural Energy Institute under grant no. N00014‐14‐1‐0054 from
the Office of Naval Research. The authors would like to thank both HNEI and ONR for the opportunity to
pursue explore the potential for this technology. The authors believe that desiccant cooling applications
can be a significant contribution increasing the energy efficiently of building conditioning, providing a
better humidity control and foster the implementation of more environmentally friendly ways to
provide better occupant indoor environmental quality.
Project Summary – Overview of Finding and Conclusion
TABLE OF CONTENTS
RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
Hawaii Natural Energy Institute Sustainable Design & Consulting LLC
November 27, 2017 Page iii
TABLE OF CONTENTS
EXECUTIVE SUMMARY .................................................................................................................................. 1
PART 1: SUMMARY REPORT ‐ OVERVIEW OF MAIN FINDING AND CONCLUSIONS ...................................... 4
1.1 The Problem of Increasing Latent Cooling Loads Compared to Heat Gain in Buildings .................... 4
1.2. An Effective Approach to Solve the Growing Humidity Problem ...................................................... 7
1.3 Conventional Liquid Desiccant Dehumidification Processes ............................................................. 9
1.4 Proposed Low‐Flow Liquid Desiccant Technology Used in the Project ........................................... 11
1.5. Proposed System Integration of LD Technology with Sensible Cooling Technologies ................... 13
1.6. Energy Performance of the Proposed Integrated LDAC system .................................................... 15
1.7. Projected Benefits of Improved IEQ and Wellness Created by Proposed LDAC System ................ 19
1.8 General Benefits of the Proposed LDAC Technology to Hawaii ....................................................... 23
1.9 Design of the LDAC Set‐up for Initial Tests in a Lab Controlled Environment ................................. 24
PART 2: OVERVIEW OF WORK SCOPE OF PROJECT DELIVERABLES 1 THROUGH 4 .................................... 26
PROJECT SUMMARY ‐ POWER POINT PRESENTATION ............................................................................... 43
Project Summary – Overview of Finding and Conclusion
EXECUTIVE SUMMARY
RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
Hawaii Natural Energy Institute Sustainable Design & Consulting LLC
November 27, 2017 Page 1
EXECUTIVE SUMMARY
This report, “Project Task 5: A Summary Report of the Project Work”, is Deliverable 5 of the project
“Desiccant Dehumidification to Support Energy Efficient Space Conditioning Systems for Hawaii – Project
Phase 1: Design Study and Project Site Selection”. Sustainable Design & Consulting (SDC) LLC is
performing the work under contract (RCUH P.O. #Z10143891) for Hawaii Natural Energy Institute (HNEI).
This report summarizes the main findings and conclusions and provides an overview about the scope of
project work presented in four previously submitted deliverables.
Introduction
With buildings becoming increasingly energy efficient, their heat gain, which must be removed by space
conditioning, switches from mainly sensible cooling, which lowers indoor temperatures, to increased
latent cooling loads, which remove moisture.
Standard Heating Ventilation Air Conditioning (HVAC) systems typically operate under part load for most
of their operating hours. In part load operating conditions, standard HVAC systems can remove a
maximum of about 30% of latent cooling loads. When they are oversized, what frequently happens is
that the latent load removal capacity under part load can diminish to 15%. In Hawaii’s hot and moist
climate, the latent loads of buildings are at times as high as 40%, and even higher levels if ventilation air
rates are increased to provide better indoor air quality (IAQ).
Too high levels of indoor humidity negatively affect air quality and carry health risks for occupants. Too
high humidity levels also deteriorate building materials through undesired growth of fungi and increased
outgassing of chemical compounds.
These humidity related problems have long been recognized as serious risks to occupants and building
structures, but cost‐effective solutions are hampered by the fact that standard AC systems are
challenged to deal effectively with elevated indoor humidity levels. The main barrier has been that in
standard AC systems, sensible and latent cooling cannot be effectively separated, since these systems
are designed to first remove sensible cooling load before latent cooling.
Discussion
Consequently, an effective approach to avoid indoor humidity problems is to decouple sensible and
latent cooling. This can be done through conventional cooling based dehumidification systems; but far
more effective are desiccant systems, which do not require cooling the moist supply air to below‐
dewpoint temperatures. This report proposes to use liquid desiccant dehumidification systems which
have significant advantages over their solid desiccant counterparts.
Liquid desiccant dehumidification systems have been successfully used for high performance air drying
applications, mainly for industrial processes and to a lesser extent for specific building applications, such
as hospitals, libraries and museums. Wider liquid desiccant cooling applications for general HVAC
systems have been less common, mainly due to operational barriers, such as considerable maintenance
and problems of carryover of liquid desiccant solution droplets.
Project Summary – Overview of Finding and Conclusion
EXECUTIVE SUMMARY
RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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November 27, 2017 Page 2
More recent technology developments of advanced so‐called “low‐flow” liquid desiccant technology
have started to overcome these barriers. This new technology has matured to a point where commercial
products are now available for dehumidification in general HVAC. These new liquid desiccant systems
have significant benefits in terms of lower energy use and the opportunity for use of solar heat or waste
heat.
This project has identified a suitable liquid desiccant (LD) dehumidification product by the US company
AIL Research Inc. for a pilot installation in Hawaii. The LD core system will be combined with energy
effective sensible cooling and peripheral systems, which together establish the liquid desiccant air
conditioning (LDAC) system. This LDAC system will be tested in a pilot installation; in the first phase in a
lab‐controlled environment, and in the second phase as a regular HVAC unit for a regularly occupied
space. The pilot installation will showcase the benefits of the technology and validate projected energy
savings as well as improvements to occupant thermal comfort and air quality of the conditioned spaces.
Increasing ventilation rates have been reported to be an important factor to achieve higher indoor air
quality (IAQ). For standard HVAC, increased ventilation air rates, however, typically come with a
significant energy burden due to increased latent cooling demand. The proposed liquid desiccant air
conditioning (LDAC) system supports energy efficient dehumidification, even at higher ventilation rates,
since overcooling and system reheat is avoided in LDAC systems. An optimum indoor humidity level is at
45% relative humidity (RH). This RH level avoids potentially serious indoor humidity problems and
increases the IAQ.
An evolving performance metric for buildings is the level of indoor environmental quality (IEQ) and
wellness for the occupants. IEQ has many aspects that are directly attributable to the HVAC system
performance including thermal comfort (TC) and IAQ. This report presents recent studies that correlate
improvements in IAQ and thermal comfort with quantifiable financial gains for companies, which
operate in improved indoor building spaces. The financial gains can be expressed in avoiding unhealthy
indoor conditions, which in turn lowers absenteeism and health related costs, and improving
productivity of employees. Building owners can take advantage of increased net operating income and
cap rate as companies and tenants increasingly look for healthy and productive buildings.
An example comparison of space conditioning performance using a standard HVAC and an advanced
liquid desiccant was carried out for an 8,000‐sqft. office space. The projected energy savings of the
liquid desiccant system with solar heat (for desiccant regeneration) was predicted at about 30% when
compared to standard HVAC system even though the ventilation air rate of the LDAC system was double
that of the ventilation rate for the standard AC system.
Using recently published expected revenue premiums for office spaces with better IAQ of up to $6,500
per person, the financial benefits of better IEQ was estimated for the company occupying the improved
office space. The results, which used a conservative 50% of the suggested $6,500 cost benefits, suggest
that the equivalent benefits of higher ventilation rates, improved humidity and IAQ control outperform
the projected energy savings by 96% to 4%, respectively. These results put into perspective how an
Project Summary – Overview of Finding and Conclusion
EXECUTIVE SUMMARY
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advanced HVAC system, such as the liquid desiccant system, can save energy and create high value by
providing a better indoor environmental climate.
For Hawaii, energy efficiency HVAC technology and the use of renewable energy for these HVAC systems
is essential to achieve the state’s energy goals. Providing good energy performance and excellent indoor
air quality and thermal comfort is the differentiating quality of the proposed LDAC.
This report has two parts. Part 1 discusses the challenges of increased latent loads and proposes an
innovative low‐flow liquid desiccant dehumidification process design. This section describes the benefits
of the proposed LDAC to Hawaii, significant energy savings and advanced indoor humidity control, that
are essential to the hot and humid climate of Hawaii. Part 2 summarizes the scope of project work
contained in four previously submitted deliverables.
Summary Project Conclusions and Recommendations: The wider use of green building technologies
helps Hawaii to achieve its important goal of reducing energy. On the flip side, in more energy
efficient buildings that are tightly sealed when air conditioned, humidity problems can arise,
especially in Hawaii’s hot and humid climate. This causes significant risks to occupants and the
building itself, as healthy indoor relative humidity levels are often not effectively maintained with
standard HVAC systems. New HVAC strategies can provide safe removal of increasing humidity loads
and, at the same time, significantly increase energy efficiency with the use of renewable thermal
energy in building HVAC. The HNEI and SDC project team has conducted a significant research effort
in new types of HVAC systems that are based on the evolving “low‐flow” liquid desiccant technology.
The new HVAC technology is called Liquid Desiccant Air Conditioning (LDAC). LDAC systems can
reduce energy imported to Hawaii as well as carbon emissions. The average level of these savings is
30%, but can be as high as 80% when all cooling loads are provided by thermally driven chillers. In
addition, the LDAC technology offers significant financial benefits to companies as they can reduce
health related costs and boost office productivity with a healthy indoor environment. These financial
benefits can surpass energy cost savings many times over. LDAC technology clearly outperforms
standard HVAC in achieving good indoor environmental quality, through improved ventilation and
advanced humidity control. It also significantly improves indoor air quality and thermal comfort. LDAC
must be field tested in Hawaii to optimize its performance in the hot and humid climate of Hawaii.
The project team of HNEI and SDC has prepared the design to install a pilot LDAC system as a key first
step for broader deployment of LDAC in Hawaii.
Project Summary – Overview of Finding and Conclusion
PART 1: SUMMARY REPORT ‐ OVERVIEW OF MAIN FINDING AND CONCLUSIONS
RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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PART 1: SUMMARY REPORT ‐ OVERVIEW OF MAIN FINDING AND CONCLUSIONS
Fundamental Challenges of Increasing Latent Cooling Loads in High‐performance Buildings and the use
of Liquid Desiccants for Energy Efficient and Advanced Humidity Control and IEQ improvements.
1.1 The Problem of Increasing Latent Cooling Loads Compared to Heat Gain in Buildings
Starting in the late 1970s, and in response to national energy crises, a steady pattern of improved
energy efficiency in buildings emerged. National energy codes and guidelines prescribed improvements
in buildings to reduce energy consumption. State governments developed or adopted even more strict
energy codes into their own regulations. Figure 1.1.1 illustrates the relative performance improvements
due to mandated energy codes for buildings and building technology compared to a 1975 baseline.
Figure 1.1.1 shows the historical and the predicted reduction of energy use in buildings, as required by
different energy codes.
Figure 1.1.1: Historical and future predicted development of energy efficiency based on energy codes
The magnitude of energy use in buildings is closely related to the energy required for space
conditioning. Internal and external thermal gains require mechanical cooling energy to remove heat gain
from the conditioned spaces. Figure 1.1.2 illustrates the types of external and internal thermal gains in
buildings that increase energy demand for space conditioning.
Project Summary – Overview of Finding and Conclusion
PART 1: SUMMARY REPORT ‐ OVERVIEW OF MAIN FINDING AND CONCLUSIONS
RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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Figure 1.1.2: Typical Heat gain processes in buildings The indices 1‐A through 1‐G are cross referenced and further described in Section 1
The primary improvements to offset these heat gains 1‐A through 1‐G in Figure 1.1.2 include:
(1‐A) High performance windows reduce the conductive and radiative heat transfer from
windows through reduction of solar gain and adding insulation to lower conductive gain.
(1‐B) Shading of windows reduces the solar gain by avoiding heat transmittance into the
building.
(1‐C) Increased wall insulation through adding higher “R‐value” walls layers reduces conductive
heat transfer.
(1‐D) Sealing the envelope and tightening envelope penetrations lowers the convective heat
transfer. Effective envelope sealing also minimizes intrusion of moisture into the building.
(1‐E) Cool roof technology significantly reduces heat gain through roofs and attics. These
technologies include a range of measures that includes reflective and radiative roof
materials, radiant barriers and attic ventilation.
(1‐F) High performance appliances and equipment reduce the indoor electricity demand and
therefore the indoor heat gain.
(1‐G) High performance lighting, such as LED and CFL, reduces lighting related energy use and
thermal gain. The increased use of controlled daylighting augments electric lighting at no
energy cost.
Project Summary – Overview of Finding and Conclusion
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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The improvements in building technologies described serve to reduce the sensible cooling loads
which must be managed by HVAC systems. Conversely, the latent cooling loads remain unchanged. With effective sealing of the envelope and relatively constant indoor moisture sources, future latent
loads are projected to either remain constant, or increase should the ventilation rates increase.
Figure 1.1.3 illustrates the projected significant decrease in sensible heat gain and the slight increase
in latent cooling loads. Figure 1.1.3 (a) provides a qualitative description of the distribution of
sensible and latent heat loads. Figure 1.1.3 (b) shows the latent heat ratio (LHR, the ratio of latent to
overall cooling load) which when added to the sensible heat ratio (SHR,) is equal to one. The more
frequently used SHR is defined as the ratio of the sensible cooling load over the sum of the sensible
and latent cooling loads.
(a) Distribution of sensible and latent cooling loads (b) Sensible and latent heat ratio
Figure 1.1.3: Increase of sensible and latent loads over time and decrease of latent heat ratio
Standard HVAC systems are designed to primarily remove sensible cooling loads and manage the latent
cooling load in the process. With an increasing latent heat ratio, and therefore lower SHR, standard
HVAC systems are not well equipped to remove the moisture, especially under partial load conditions.
Partial loading is the dominant operational condition under which HVAC systems operate. Under partial
loads, cooling coils will cycle in an ON‐OFF pattern, controlled by temperature set points. With supply air
passing over cooling coils that are above dew point, and the evaporating of condensate from wet coils,
the efficiency of latent cooling load removal is reduced. Figure 1.1.4 shows a reduction in moisture
removal performance for standard HVAC systems under higher latent heat ratios and lower sensible
heat ratios. Figure 1.1.4 suggests that standard HVAC systems can contribute to unhealthy indoor
conditions due to high relative humidity (RH) levels resulting from the SHR decrease.
0
0.2
0.4
0.6
0.8
1 2 3 4 5 6 7 8
Sensible or Latent Heat [BTU
/h]
Time scale (arbitray)
Sensible Heat Latent Heat
0.2
0.4
0.6
0.8
0.2
0.4
0.6
0.8
1 2 3 4 5 6 7 8
Latent Heat Ratio [LHR]
Sensible Heat Ratio [SHR]
Time scale (arbitray)
SHR LHR
Project Summary – Overview of Finding and Conclusion
PART 1: SUMMARY REPORT ‐ OVERVIEW OF MAIN FINDING AND CONCLUSIONS
RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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Figure 1.1.4: Indoor RH vs. building Cooling Load SHR with conventional unitary AC equipment
The figure describes that with decreasing SHR and increasing LHR, standard unitary system do not effectively manage the latent cooling load, thereby increasing the indoor RH levels to potentially unhealthy values.
Source: TIAX (2003) “Matching the Sensible Heat Ratio of Air Conditioning Equipment with Building Load SHR”
effectiveness with lower SHR
Conclusions:
As buildings become more energy efficient, sensible heat gains diminish while latent cooling
loads remain or are likely to increase with increasing ventilation rates.
Consequently, humidity‐related health hazards and moisture‐caused building damage can be
phenomena that will increase as buildings become more energy efficient and tightly sealed,
thus requiring controlled ventilation.
Standard HVAC systems are ill equipped to manage higher latent load ratios, necessitating
new technologies and operational procedures to counter this trend.
1.2. An Effective Approach to Solve the Growing Humidity Problem
Standard HVAC removes the latent load in the ventilation air by passing the air over cooling coils that
are maintained below dewpoint temperatures. The moisture in the air is thus removed as condensate
which drains from cooling coils. When passing over the coils, the air also removes sensible heat. If the
indoor sensible heat gain is lower than the cooling capacity of the supply air, the cooled air must be
reheated before entering the space to avoid overcooling and negatively affecting thermal comfort of the
occupants. System reheat consumes significant heat energy, often supplied by natural gas, but
sometimes as electricity where natural gas is not readily available.
Standard HVAC systems thus cannot readily separate sensible from latent cooling load removal.
Typically, standard HVAC systems control cooling cycles with a HIGH to LOW temperature setpoint
Project Summary – Overview of Finding and Conclusion
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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band, rather than humidity. Precise indoor humidity control would require HVAC systems that (1)
control BOTH operative temperature and humidity independently and (2) provide correctly sized
sensible and latent removal. Figure 1.2.1 shows a basic process diagram of (a) standard HVAC operation
with simultaneous sensible and latent cooling load removal and (b) advanced HVAC which decouple
sensible and latent load removals.
(a) standard HVAC operation with simultaneous sensible and latent cooling load removal
(b) advanced HVAC that decouples sensible and latent load removal.
Figure 1.2.1: Basic processes of coupled and decoupled sensible and latent cooling load removal
Conventional cooling based dehumidification systems have the disadvantage of requiring reheating the
cooled air. Desiccant dehumidification has the advantage that the moisture in the supply air can be
removed at above dewpoint temperature and therefore no reheat is required. In addition, desiccant
dehumidification can use solar or waste heat for its system regeneration process, thereby significantly
reducing electric energy needs.
Project Summary – Overview of Finding and Conclusion
PART 1: SUMMARY REPORT ‐ OVERVIEW OF MAIN FINDING AND CONCLUSIONS
RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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Conclusions:
Standard HVAC systems rely on simultaneous sensible and latent cooling load removal.
This combined heat removal process has been adequate with high SHR buildings, but is not
well suited for HVAC applications when sensible cooling loads decline as buildings become
increasingly energy efficient.
A suitable mitigation of insufficient latent cooling load removals is “decoupling” sensible and
latent cooling loads through separate controls and dedicated system components that
independently lower temperature and remove water vapor from conditioned spaces.
Using liquid desiccant dehumidification avoids energy for reheat and separates the
dehumidification process from the sensible indoor air temperature.
1.3 Conventional Liquid Desiccant Dehumidification Processes
There are two desiccant technologies, which are presently used in HVAC applications; solid and liquid
desiccants. Solid desiccant systems are more widely used in building conditioning, especially in the form
of “desiccant wheels”. Liquid desiccant systems have primarily been used for specific dehumidification
processes, such as in special industries or selected institutional buildings with the need for precise
humidity control, including hospitals, libraries and museums. The liquid descant dehumidification
process has been identified as having advantages regarding energy and IEQ properties over solid
desiccants and was selected for this project.
Figure 1.3.1 shows a conventional liquid desiccant dehumidification system, operated as a packed
column with external cooling and regeneration, into which the liquid desiccant solution is injected. As
the desiccant solution trickles down the packing elements, moist air moves in counter flow direction.
Water vapor in the moist air migrates towards the surfaces of the desiccant solution, thereby drying the
air. As the desiccant solution becomes saturated with water vapor, it is pumped to the regenerator
where heat energy removes the moisture from the desiccant solution with its hot and dry scavenger air
stream.
Figure 1. 3.2 illustrates the basic thermodynamic processes of liquid desiccant dehumidification. Figure
1.3.2 (a) shows the three main process steps in the liquid desiccant dehumidification process which are
sorption, desorption and cooling. Figure 1.3.2 (b) illustrates sorption process, also called absorption. The
water vapor pressure in the air is higher than at the desiccant solution surface, thus moisture is
absorbed into the desiccant. As more water vapor is absorbed by the desiccant, water vapor pressure
declines in the air and increases at the desiccant surfaces. The desiccant solution becomes “saturated”.
Absorption heat is then liberated increasing the temperature of the desiccant solution. The heat of
absorption has to be rejected, typically by an evaporation cooling tower. Figure 1.3.2 (c) illustrates the
desorption process in the desiccant regenerator. The desiccant solution is pumped from the absorber to
the regenerator and comes into surface contact with a heated scavenger air flow. Water vapor pressure
of the liquid desiccant surfaces is higher than in the heated scavenger air. Consequently, water vapor
moves from the desiccant solution to the air, driven by the water vapor pressure differential.
Project Summary – Overview of Finding and Conclusion
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Figure 1.3.1: Conventional liquid desiccant dehumidification system, operating as a packed column with external cooling and regeneration
(a) Three main process steps in the desiccant dehumidification are of sorption, desorption and cooling
(b) Sorption process:humidity (water vapor) moves from the humid air to the desiccant because water vapor pressure is higher in the moist air.
(c) Desorption: humidity moves from the desiccant to the hot scavenging air because water vapor pressure is higher at the desiccant surface
Figure 1.3.2: Basic processes in liquid desiccant dehumidification
Project Summary – Overview of Finding and Conclusion
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Conclusions:
Liquid desiccant dehumidification has been used successfully for several decades to provide
advanced dehumidification in certain industrial and institutional applications.
Liquid desiccant systems have advantages over solid desiccant systems for HVAC applications
that include energy efficiency, use of renewable energies and better indoor air quality.
1.4 Proposed Low‐Flow Liquid Desiccant Technology Used in the Project
Conventional liquid desiccant dehumidification systems have higher maintenance and operational
challenges compared to standard HVAC technology. This has been a barrier to their wider use in general
HVAC applications. A new liquid desiccant dehumidification technology, the so‐called “low flow”
desiccant process, was developed to avoid these problems. The new low flow liquid desiccant
technology has internally heated and cooled process vessels, and a significantly lower desiccant flow
rate. This avoids desiccant droplet carryover to the conditioned spaces and provides for smaller process
vessels. The new liquid desiccant technology also requires less maintenance and is more energy
efficient.
Figure 1.4.1 shows the low‐flow liquid desiccant technology developed by AIL Research Inc. (AILR). The
AILR product was selected for this project after evaluating six liquid desiccant vendors. The figure shows
a schematic rendering and a photo of an internally cooled absorber. Unlike the packed columns type
process vessels of conventional systems, the new low‐flow technology uses evaporative matrix in the
absorber and regenerator. Desiccant solution slowly flows downwards through the evaporative matrix
while being in contact with air passing through it. Copper tubes integrated into the matrix, which
contains a flow of cooling or heating water, provide the internal heat sink and source for the absorber
and regenerator heat, respectively.
Figure 1.4.2 shows selected previous commercial and demonstration HVAC projects with AILR liquid
desiccant technology products. The figure shows (a) packaged LDAC systems containing absorber and
regenerator, (b) and (c ) LDAC units with solar thermal systems that provide heat to the regenerator.
Presently, AILR’s LDAC technology is not widely used, since low‐flow liquid desiccant dehumidification in
building HVAC is an evolving and emerging innovative technology, and is therefore unfamiliar to most
operators. But the benefits of this technology, which are discussed in more details later in this this
report, are particularly compelling for the hot and humid climate and unique energy market of Hawaii.
Project Summary – Overview of Finding and Conclusion
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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(a) AILR low flow" LD dehumidifier with three
main components: the conditioner, the regenerator and the interchange heat exchanger (IHX)
(b) The AILR patented absorber and regenerators design. Cooling tube are imbedded into an evaporative medium
Figure 1.4.1: The AILR “low flow” liquid desiccant technology
(a) LDACs installed at supermarkets in California,
in Seal Beach and the other in Tustin.
(b) (Above) An AILR LD unit was installed at a supermarket in Hawaii. The process heat for desiccant regeneration was supplied by solar thermal system.
(c) (Left) An AILR LD unit was installed Tyndall AFB. Hot water is provided by a 1,350‐square foot array of evacuated‐tube solar collectors.
Figure 1.4.2: Selected previous
commercial and institutional projects with AILR liquid desiccant technology products.
Project Summary – Overview of Finding and Conclusion
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Conclusions:
The liquid desiccant technology of AIL Research Inc. was selected from several vendors and
technology developers.
AILR’s “Low flow” liquid desiccant technology is more suitable for general HVAC applications.
The AILR technology has been used in several commercial and institutional projects and has
matured to a point where a wider market entry can be anticipated.
1.5. Proposed System Integration of LD Technology with Sensible Cooling Technologies
The liquid desiccant (LD) system dehumidifies the supply air to such an extent that the indoor latent
load, e.g. the water vapor introduced to the conditioned space, can be safely absorbed by the dry air
and expelled with the discharge air. The LD system does not, however, remove sensible heat, and
therefore separate sensible cooling technologies must be installed to reduce the temperature in the
conditioned space. In this technology comparison it was assumed that the indoor air has been
sufficiently dehumidified, e.g. the dew point has been sufficiently lowered, that the chilled water supply
to the sensible cooling units remains above dew point and therefore condensation does not occur.
During the project the following sensible chilled‐water cooling technologies were considered:
5‐A. Air handling units (AHU) provide sensible cooling to the primary air supply. AHU units are
installed inside the supply air duct system. The cooled supply air must be sufficiently large to
remove the sensible and latent load from the indoor space. If the ventilation air cannot be
separated from recirculated air flow, the AHU configuration does not decouple sensible and
latent load removal.
5‐B. Fan coil units (FCU) have internal air fans that recirculate indoor air over cooling coils. The
sensible cooling by the FCU can act independently from the dehumidification process, which is
provided by cooling coils in the primary supply air. The cooling capacity of the FCU is
dependent on temperature differentials of cooling coils and indoor air as well as air flow rate
through the FCU.
5‐C. Chilled ceilings (CC) operate primarily on radiant, and to a lesser extent, on passive convective
heat transfer. The main CC performance parameter is the size of the radiant ceiling area. The
temperature of the CC cannot be too low because this would establish a radiant asymmetry,
that is, the temperature differential between the radiant ceiling and the mean radiant
temperature (MRT). A too high a radiant asymmetry would create thermal discomfort (a chill)
to occupants.
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5‐D. Active chilled beams (ACB) provide sensible cooling load by using the primary supply air to
induce recirculating movement of indoor air over cooling coils inside the ACB. ACBs have been
frequently used in HVAC installations. Since the ACB operates requires a significant minimum
primary supply air flow rate for indoor air induction, sensible and latent load removal cannot
be completely decoupled.
5‐E. Passive chilled beams (PCB) are similar to ACBs, but they do not use primary supply air to
induce indoor air flow over the cooling elements inside the chilled beam. The PCB technology
relies solely on density‐induced air movement of cooler and denser sinking from the PCB. The
PCB has no internal fan nor a connection to the primary air duct. Conventional PCBs have a
lower heat transfer rate than ABSs, but newer designs of PCBs have significantly improved the
thermal performance. These new PCB designs have significantly increased both the convective
as well as the radiant heat transfer rates. Using PCBs allows complete decoupling of sensible
and latent cooling load removal.
Option 5‐E, the passive chilled beam, was selected for this project as thermal technology to remove
indoor sensible cooling loads.
Figure 1.5.1 shows the PCB technology selected for the project, the Barcol’s “Radiant Wave” product.
Radiant Wave panels will be suspended below the ceiling. Placing the panel at a prescribed distance
from the ceiling increases the convective heat transfer rates and also provides a significant portion of
the cooling capacity as radiant heat transfer.
Cross section through Barcol Radiant Wave Barcol Radiant ‐Wave PCB technology
Figure 1.5.1: PCB technology selected for the project, Barcol Radiant Wave
Figure 1.5.2. shows a schematic of the preferred configuration of the proposed LDAC system with liquid
desiccant dehumidification and sensible cooling using passive chilled beams (PCBs). In Figure 1.5.2, a
water‐to‐air heat exchanger is added downstream of the LD unit to allow a controlled removal of
sensible heat from the dried air stream coming out of the desiccant absorber unit. Figure 1.5.2 also
illustrates the use of a ceiling fan to add cost‐effective convective cooling of occupants. Using ceiling
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fans in the proposed LDAC system is more prudent than using ceiling fans in spaces with standard HVAC,
since ceiling fans can indirectly cause humidity problems in standard HVAC decreased ON‐time. When
operating ceiling fans, occupants tend to increase the temperature control set‐point thereby making
ON‐OFF cycling in standard HVAC systems more likely, resulting in insufficient dehumidification. In the
proposed LDAC system, however, the level of dehumidification is controlled independent of the
temperature set‐point, therefore increasing the set point will not affect the humidity removal.
Figure 1.5.2: Configuration of the LDAC system with desiccant dehumidification and sensible cooling using passive chilled beams (PCBs).
Conclusions:
Several sensible cooling technologies were considered for the proposed LDAC system.
An innovative passive chilled beam (PCB) design with high heat transfer rates was selected to
provide sensible cooling load removal.
The advantages of the PCB include good energy performance, easy installation without
connection to supply air ducting and complete decoupling of sensible and latent loads.
1.6. Energy Performance of the Proposed Integrated LDAC system
The proposed LDAC system provides significant electrical energy savings over standard HVAC systems.
The following are the main factors that improve energy efficient operation:
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6‐A. The LD dehumidification system uses only a limited amount of electricity for fans and pumps.
The system uses thermal heat for desiccant regeneration and evaporative cooling for the
heat sink of absorption heat of the absorber. The LD system does not use a vapor
compression cycle. The heat for desiccant regeneration would preferably come from a solar
thermal system or provided by waste heat.
Figure 1.6.1 illustrates the energy advantage of the LDAC system over standard HVAC with
cooling based dehumidification. Figure 1.6.1 shows the psychrometric process of a standard
HVAC system (Path 1) where the air is cooled to the desired dew point and then reheated to
avoid thermal discomfort for occupants in the conditioned space. The LDAC system (Path 2),
on the other hand, does not require as much energy to attain the target indoor temperature
and humidity, since overcooling and reheating is avoided. Considering the basic
psychrometric process and required reheat illustrated in Figure 1.6.1, the energy savings of
the LDAC over the standard HVAC is 33%.
Figure 1.6.1: Psychrometric performance of LDAC and standard HVAC The standard HVAC requires 64.8 tons (54+10.8 tons) along Path 1 The LDAC requires 43.2 tons along Path 2; this is a saving of 33%
6‐B. The passive chilled beams do not use electric energy directly, but only indirectly by receiving
quantities of chilled water provided by water pumps. Moving heat from the room to an
external heat sink by relatively small volumes of cooling water is much more energy efficient
than moving larger volumes of cooled air. The passive chilled beams also do not have to rely
on primary supply air to induce air movement over the internal cooling elements. This saves
fan energy, since the indoor air movement initiated by the PCB relies on density induced air
movement and not on forced air.
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6‐C. The sensible cooling units require heat sinks which can be supplied by either conventional
vapor compression (VC) chillers or be thermally driven chillers, such as adsorption chillers.
Using VC chillers as the heat sink for the proposed LDAC can take advantage of a better
energy performance of the chiller, since the chiller can operate at higher chilled water
temperatures, which increases the thermal performance. Using adsorption chillers requires
installation of solar thermal systems with a thermal buffer storage tank. A prudent system
design using adsorption chillers would implement some form of stand‐by heat source to
provide for heating water supply interruption due to intermittent availability of solar heat.
6‐D. Ceiling fans provide very cost‐effective and energy efficient convective cooling for occupants.
6‐E. Evaporative cooling was investigated but not selected because of the limited efficiency
caused by the typically humid, high wet‐bulb temperatures in Hawaii’s climate. Using the
discharged air from the conditioned space, which has a lower RH than the outside air, is an
option, but provides only limited sensible heating capacity.
6‐F. Enthalpy recuperation (e.g. total energy recovery) exchanges sensible and latent cooing loads
between the discharge and supply air flows. This can save significant amounts of energy.
Since the target indoor and outside dry bulb temperatures do not differ significantly in the
proposed LDAC, only the latent heat exchange would be considered as a viable energy saving
proposition. New enthalpy recuperation technologies use low maintenance and cost‐
effective membrane technology for the transfer of humidity between discharge and supply
air.
As a system sizing example, the project evaluated the energy performance of the proposed LDAC system
serving an 8,000‐sqft. office sample space, and compared the energy use with a standard HVAC system.
The LDAC used a ventilation flow rate that was twice that of a standard HVAC based on minimum
ASHRAE ventilation rates. Using the energy saving features 6‐A through 6‐D, as defined above, the
predicted energy savings of the proposed LDAC were calculated. Figure 1.6.2 shows the results and the
comparison of annual energy costs between a standard HVAC and the proposed LDAC system. The
figure indicates a $9,000 energy cost saving, using energy prices typical for Hawaii.
The results of the energy analysis suggested that the proposed LDAC would save approximately 30% of
electric energy compared to the baseline of a standard HAC system. These predicted energy savings are
similar to energy savings reported by a 2014 NREL study for several installations of AILR liquid desiccant
systems. The energy savings of the different AILR LDAC systems reported by NREL are shown in Figure
6.3.
Project Summary – Overview of Finding and Conclusion
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Figure 1.6.2.: Comparison of annual energy costs between a standard HVAC and the proposed LDAC system. The energy calculation for a sample 8,000‐sqft office.
Figure 1.6.3: Predicted energy savings of several AILR liquid desiccant systems reported by NREL
The equivalent carbon emissions were evaluated for two alternative system configurations of the
proposed LDAC, one (a) with a conventional vapor compression chiller and the other (b) with a thermally
driven adsorption chiller, for sensible cooling load removal. These carbon emissions were then
compared with carbon emissions of a standard HVAC system. Figure 1.6.4 shows that the alternative
LDAC system configurations (a) and (b) were 42% and 83% below the equivalent carbon output of the
standard HVAC, respectively.
$30,000
$21,000
$9,000
$0
$10,000
$20,000
$30,000
$40,000
Conventional DX HVAC system;min. ventilation rate
Proposed LDAC system; doublemin. ventilation rates
Energy Costs / Savings
Energy costs Energy savings
Project Summary – Overview of Finding and Conclusion
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Figure 1.6.4: Percentage comparison against the baseline carbon equivalent emission of the conventionHVAC system
Conclusions:
The proposed LDAC system with vapor compression for sensible cooling load removal
estimated a 30% energy savings relative to a standard HVAC system.
The LDAC system provided a twice as high ventilation air flow rate than the standard HVAC.
Therefore, comparable energy savings should be even larger.
The projected energy savings are consistent with performance evaluation of several AILR
LDAC systems, published by NREL in 2014.
The projected carbon emission reduction of the proposed LDAC was evaluated as 42% and
83% relative to standard HVAC technology.
1.7. Projected Benefits of Improved IEQ and Wellness Created by Proposed LDAC System
In the past, high performance buildings were primarily evaluated by the level of reductions in energy use
and environmental impact. Occupant comfort and wellness were considered somewhat relevant, but
typically not quantifiable as a primary decision parameter. This has changed, and increasingly terms such
as “heathy and productive buildings” and “wellness in buildings” are growing in importance when
quantifying the benefits of green buildings.
While sustainable buildings were often promoted as “good for the environment”, healthy and
productive buildings that offer excellent indoor environmental quality have direct and quantifiable
financial benefits for companies and building owners/operators. A healthy and productive indoor
environment has been shown to reduce absenteeism and increase productivity of employees. Retaining
important talent and reducing employee turnover saves companies far greater costs than is spent on
58%
100%
17%
0%
20%
40%
60%
80%
100%
1. Proposed LDACsystem, with
vapor comprestionchiller
2. Standard(baseline) AC
3. Most efficientLDAC system
all solar
Carbon Dioxide Equivalent [% of baseline]
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energy. These human resources related factors have been proven as being directly and positively
affected by high quality indoor environmental conditions.
Figure 1.7.1 presents two health building standards, (a) the “9 Foundations for Healthy Buildings”
developed by the Harvard Healthy Building Program, and (b) the WELL Building Standard. The Harvard
Health Buildings Program developed projected cost savings and increased revenues through improved
indoor environmental quality. Figure 1.7.1 (c) presents how total office related costs for companies are
distributed between personnel cost, rent & technology and energy. Figure 1.7.1 indicates that energy
costs play only a minor cost factor whereas personnel costs make up the lion’s share of the “cost of
doing business”. This distribution of cost indicates that even small reductions in personnel costs or
increases in employee productivity can have a larger impact than reductions in energy costs.
Figure 1.7.2 shows the optimal value of indoor relative humidity (RH) of 45%, which should be
maintained to avoid humidity related health problems as well as problems to the building itself.
(a) Harvard Healthy Building Program; Guidelines for healthy and productive buildings
(b) The WELL Building Standard; provides standards for healthy and productive buildings
Tangible financial benefits through IEQ and Wellness
(c) Typical distribution for the “cost of doing business” for office workers
Figure 1.7.1: IEQ and Wellness in buildings become tangible benefits for companies
Project Summary – Overview of Finding and Conclusion
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Figure 1.7.2: Levels of activity of harmful organisms and chemical interactions as a relationship of indoor RH The value of 45% RH has been identified in the literature as optimum indoor RH
The Harvard estimates specifies an average annual $6,500 per employee increase in revenues and cost
reduction when indoor air quality is improved through increased ventilation. The same example case of
an 8,000‐sqft office space was used to estimate financial benefits from improved indoor health and
wellness conditions. For this estimate, the following aspects of indoor environmental improvements
were considered based on the performance characteristics of the proposed LDAC:
Increasing the ventilation rate of the conditioned space by 100% over ASHRAE recommended
minimum ventilation rates for office spaces.
Using a dedicated outdoor air system (DOAS) which avoids recirculation of air as used in standard
HVAC systems. Pollutants and pathogens are directly transported to the outside by the DOAS
system, and distribution of these within the conditioned space through recirculated air is avoided.
Precise humidity control at an optimum 45% relative humidity level increases the indoor air
quality, since 45% is the RH level that avoids the growth and hazards cased of harmful pathogens
(refer to Figure 7.2)
Advanced filtration, removal of pollutants and pathogens is provided by the LDAC system, where
the liquid desiccant solution acts as advanced filtration and disinfection devices.
For the example 8,000‐sqft office, increased revenue and cost reductions due to reductions in building
related sickness and absenteeism, as well as increased productivity, was calculated. We used a
conservative 50% of the Harvard suggested $6,500, which equals $3,250 per employee increase in
revenues. The results of this analysis for the 8,000‐sqrt. office space are shown in Figure 1.7.3. The
results indicate that the increased revenues or avoided costs of building related sickness and
absenteeism of employees, and the increase in productivity through increased IEQ and wellness, is
significantly greater than the energy savings by the LDAC. The calculated energy cost savings are only 4%
of total cost savings, compared to the 96% of total cost savings represented by the better productivity
and reduced health costs for employees based on better IEQ and wellness.
Relative Humidity
Organisms ↓ 0 10 20 30 40 50 60 70 80 90
Bacteria
Viruses
Fungi
Mites
Allergic Rhinitis & Asthma
Respiratory Infections
Chemical Interactions
Ozone production Optimum level of R
H
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While energy savings are essential for Hawaii’s future energy goals, providing a high indoor
environmental quality to occupants creates direct and significant incentives to companies and building
owners and operators to pursue “Green Buildings”.
Figure 1.7.3: Comparison between calculated energy cost savings and reduced costs through better IEQ and wellness The calculations are based on the following assumptions: 8,000‐sqft. office 110 sqft. per person 50% of Harvard
figure of $6,500 per person productivity gain and les health risk = $3,350 per person
Conclusions:
With high indoor environmental quality through advanced LDAC systems, companies and
building owners / operators can secure significant financial benefits, including the avoidance
of building related health problems and increasing the productivity of employees.
For an example office space using LDAC, calculated increased revenues and avoided costs
through improved IEQ were compared to the energy savings. Resulting savings using LDAC
were as 96% and 4% of total savings, respectively.
For Hawaii, energy savings are essential to achieve the state’s imposing energy reduction
goals, but not at the expense of healthy and productive indoor environments.
Combining energy savings with the improvement of the financial performance of the
companies that provide a quality indoor environment makes the proposed LDAC technology
especially attractive.
$230,000
$9,000
$0
$50,000
$100,000
$150,000
$200,000
$250,000
Cost Savings / Increased Revenue
96%
4%
0%
20%
40%
60%
80%
100%
Percentage of Cost Savings / Increased Revenue
Calculated energy cost savings
Calculated increased productivity through better IEQ and Wellness
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1.8 General Benefits of the Proposed LDAC Technology to Hawaii
Hawaii manifests several challenges with respect to space conditioning. The climate is hot and humid
and most of the HVAC systems installed are based on design strategies that are not optimized for the
climate, nor provide optimal indoor environments for building occupants. People in Hawaii generally like
openness of spaces and the affinity to the outside climate. Adaptive comfort, a concept promoted by
ASHRAE for naturally ventilated spaces, relies on occupant’s adaptation to outside climatic conditions
and their openness to spending time in spaces with higher indoor temperatures than typically found in
spaces conditioned by standard HVAC.
The proposed LDAC system could provide a comfortable indoor environment for Hawaii with higher air
temperatures than targeted by standard HVAC, but with optimum indoor relative humidity levels. A
sufficiently high ventilation rate would provide a sense of natural freshness and create higher indoor air
quality by removing indoor odors and pollutants. Avoiding high recirculation of indoor air through a
dedicated outside air supply (DOAS) would avoid recirculation of stale and possible polluted indoor air.
Annoying noise levels would decrease as less air is flowing through air ducts. The absence of mold issues
and other pathogens through a precise maintenance of indoor RH would solve a wide range of indoor air
quality issues related to humidity. The tendency to overcool conditioned spaces will be mitigated. In
short, the proposed LDAC technology can provide a conducive indoor environment while at the same
time save energy.
The proposed LDAC technology will save energy because no fossil based energy is wasted for reheat,
since solar or other environmentally friendly thermal heat sources could be used. The proposed LDAC
especially caters to the use of energy saving naturally occurring heat sinks, such as deep well or
seawater air conditioning (SWAC). Larger SWAC systems are currently under design development for
several locations in Hawaii. The use of SWAC (or a deep well derived supply of cold water) for the
proposed LDAC system would be significantly more cost effective than current SWAC designs serving
standard HVAC. Deep cold seawater could be extracted form a shallower depth than considered for the
present SWAC designs. Using cold seawater pumped from significantly shallower depth, and at a lower
flow rate, would significantly lower the price of the most expensive system part of a SWAC system,
which is the cold seawater pipe. Using SWAC in combination with solar operated LDAC would create the
most energy efficient HVAC system possible for the local climate.
Conclusions:
On a larger scale, the proposed LDAC system can create significant value for Hawaii.
LDAC’s can save significant amounts of electric energy while at the same time create an
indoor environment that resembles conditions which are preferred by people living in Hawaii.
LDAC helps to reduce unhealthy conditions which are frequently related to excess humidity.
The LDAC can shift the energy use from imported energy sources to locally available,
renewable thermal and solar energies.
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1.9 Design of the LDAC Set‐up for Initial Tests in a Lab Controlled Environment
While the LDAC technology has already been installed in commercial and institutional buildings, it is still
an evolving technology. In particular, the combination of liquid desiccant dehumidification with the type
of energy efficient sensible cooling technologies selected for the pilot installation is creating a new type
of HVAC application. This newness requires pilot installations to develop the operational experience and
safeguard that all system parts operate as planned. It was therefore decided to install a smaller LDAC
system at a pilot location in Hawaii, to test the system under real‐world conditions for an extended time,
preferably at least a year, to cover all relevant seasonal conditions.
The planned pilot installation will occur in two phases, called Project Phase II/A and II/B. In the Phase
II/A the LDAC system will be tested in an 800‐sqft laboratory space. This first phase will test the
thermodynamic performance of the LDAC unit and how an indoor space adjusts to changing thermal and
humidity conditions controlled by the proposed LDAC system. During Phase II/A, only the research staff
and possibly a limited group of people will occupy the 800‐sqft. lab space during the initial test program.
The main objective of Phase II/A is to gain operational experience and provide valuable design guidance
to select the right pilot location for the Phase II/B.
In Project phase II/B, the LDAC will be installed at a pilot location where the system will operate as a
“normal” HVAC system, providing the occupants with sensible and latent cooling and providing ample
ventilation air. The objective of Phase II/B will be to verify that the LDAC technology can indeed provide
outstanding indoor comfort and healthy spaces while at the same time saving energy.
The design of the proposed test set‐up for the initial tests in the 800‐sqft. lab during Phase II/A has been
completed. Several details, such as shop drawings, will be completed during installation. The design is
presented in project Deliverable No. 4. Figures 1.9.1 and 1.9.2 present two example drawings which are
part of the complete design package in Deliverable 4.
The concept design of the proposed test set‐up in Phase II/B was developed. The more detail design of
the test set‐up will need to be done at a later stage, after the pilot location has been selected.
Conclusions:
Verification testing in Hawaii of the proposed LDAC system is essential to confirm the
predicted performance and benefits of the LDAC technology.
Testing of the LDAC technology under real world conditions will occur at a pilot installation in
Hawaii as presented in Project Deliverable No.4
These tests will occur in two phases, where the first phase will be initial tests in an 800‐sqft
space under a controlled lab environment without regular occupants.
The second test phase will be an installation in a regularly occupied conditioned space,
preferably an office, classroom or library.
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Figure 1.9.1: Process and instrumentation diagram of the proposed LDAC test set‐up in the space LAB 123. The full‐size sheet is presented in Deliverable No. 4, Appendix A
Figure 1.9.2: Section B‐B, overview of room LAB 123 and detail around the installed LDAC unit; The full‐size sheet is presented in Deliverable No. 4, Appendix A
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PART 2: OVERVIEW OF WORK SCOPE OF PROJECT DELIVERABLES 1 THROUGH 4
Figure 2.1 Cover images of the four project deliverables.
Figure 2.1: Cover pages of Project Deliverables 1 through 4
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Deliverable 1 summarizing Project Task 1: "Technology Review and Availability Assessment of Liquid Desiccant Systems " The main objective of this report was to identify liquid
desiccant technologies which are suitable for the pilot
installation, and select a preferred vendor to supply the
liquid desiccant technology.
SECTION 1 ‐ EXECUTIVE SUMMARY AND
OVERALL FINDINGS
SECTION 2 – INTRODUCTORY REMARKS
ABOUT DEHUMIDIFICATION
TECHNOLOGIES
This section discusses basic considerations of
dehumidification technologies and their application in
dehumidification for industrial and commercial
processes. This section also describes why
dehumidification is of increasing relevance in the
building industry and why liquid desiccant
dehumidification technology is an important solution to
provide advanced humidity control in buildings.
SECTION 3 ‐ IMPORTANT ASPECTS OF
LIQUID DESICCANT DEHUMIDIFICATION
FOR HVAC APPLICATIONS
This section summarizes important processes of liquid‐
desiccant dehumidification technologies as they relate
to HVAC applications in buildings.
SECTION 4 – RECENT LIQUID DESSICANT
DEVELOPMENTS AND IDENTIFIED FUTURE
RESEARCH NEEDS
This section presents reviewed literature that discusses
advances in liquid desiccant (LD) air dehumidification to
make this new technology suitable for residential and
commercial HVAC systems.
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SECTION 5 – REVIEW LIQUID DESICCANT
TECHNOLOGIES OFFERED BY DIFFERENT
VENDORS
This section introduces several companies which are in
the process of developing and have a track record of
developing, manufacturing and/or selling liquid
desiccant technologies. A literature research identified
seven candidate companies, which have track records
in desiccant dehumidification.
SECTION 6 ‐ RANKING OF COMPANIES AND
TECHNOLOGIES
This section present2 the methodology and results of
ranking the liquid desiccant technologies and the
vendors. This section also presented the vendor
selected for the project.
Main Conclusions:
The report assesses and ranked the liquid desiccant technologies of six vendors using a two‐tiered
ranking methodology (see Figure 2.2). The results of the ranking are presented in Figure 2.3. The East
Coast company AIL Research Inc. received the highest score and was selected as the preferred vendor.
Figure 2.2: Ranking of companies and technologies – First tier overall weights
Criteria categories (1st level) Overall weight
Ranking criteria (2nd level) (1st * 2nd level)
1 Technology maturity 25%
1.1 Technology status is mature and tested in real‐world setting 40% 10%
1.2 Technology has passed the level of concept 30% 8%
1.3 Technology has manageable but exciting innovation potential 30% 8%
sum 2nd level >>> 100% 25%
2 Prior installation /application experience of technology 20%
2.1 Products have been installed in Hawaii (tropical) climate 35% 7%
2.2 Technology has been tested in Hawaii (tropical) climate 25% 5%
2.3 Ability to use heat source specific to Hawaii (i.e. solar) 40% 8%
sum 2nd level >>> 100% 20%
3 Technology flexibility / ability to implement pilot installation 40%
3.1 Flexibility do apply in smaller installations 25% 10%
3.2 Ability to deviate from standard & prefabricated (larger) systems 15% 6%
3.3 Ability to retrofit an existing HVAC 30% 12%
3.4 Ability to build / configure HNEI hybrid system 30% 12%
sum 2nd level >>> 100% 40%
4 Communication / willingness to cooperate substantially 15%
4.1 Ease of communication 25% 4%
4.2 Willingness & ability to provide technical support for pilot install. 30% 5%
4.3 Ease to transport system to Hawaii 20% 3%
4.4 Ease to purchase domestic (US) products 25% 4%
sum 2nd level >>> 100% 15%
sum 1st level >>>>>> 100%
No 1st level 2nd level
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Figure 2.3: Total scores of ranking for six companies
Figure 2.4: Total scores of ranking for six companies
Based on the selection criteria and the assignment of how well the companies perform in accordance to
the ranking statement, the two companies AILR and L‐DCS had the highest total scores. The advantages
of AIL and L‐DCS include their flexibility to adapt their proven technology products to a narrow design
envelope, and their willingness to cooperate in fitting their technology to a suitable test site for the pilot
HVAC installation in Hawaii. AILR was finally selected because it is a US company which has had long
track record of well performing demonstration projects and several commercial product sales, including
an installation in Hawaii.
Total
scoreRank
No. 1 ‐ 7 AC Technologies 62% 3
No. 2 ‐ AIL Research Inc. 96% 1
No. 3 ‐ Be Power Tech 37% 6
No. 4 ‐ Kathabar Dehumidification Systems, Inc 56% 5
No. 5 ‐ L‐dcs GmbH 90% 2
No. 6 ‐ Menerga Apparatebau, GmbH 60% 4
Company
Project Summary – Overview of Finding and Conclusion
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
Hawaii Natural Energy Institute Sustainable Design & Consulting LLC
November 27, 2017 Page 30
Deliverable 2 summarizing Project Task 2: "Identify Application Potential in Hawaii" The main objective of this report was to discuss the
interactions of two goals of good space conditioning, (1)
save energy in providing space conditioning, and (2)
providing a good indoor environmental quality. The
report pointed out that humans are spending up to 90%
of their time indoors and thus creating a conducive
indoor environment is an increasingly important
requirement for buildings. This report discusses general
concepts and develops a generic decision model to
quantify the advantages of basic candidate system to
provide good IEQ and save energy.
SECTION 1 – EXECUTIVE SUMMARY AND
RECOMMENDATIONS
SECTION 2 ‐ REVIEW OF INDOOR
ENVIRONMENTAL QUALITY
This section discusses the following emerging focus on
indoor air quality:
On average, people spend about 90% of their time
indoors (NIBC, 2017). The issue of indoor
environmental quality is becoming more important as
buildings are more effectively sealed, thus effectively
isolating indoor space from the climatic rhythm of the
external natural environment. But as modern life
increasingly centers around indoor activities, most
people have adapted to the indoor realm as their
"natural" environment. To satisfy the human need for
affinity to the natural world, inside the built
environment, natural conditions can be emulated, and
these enhance health, productivity and the human
experience.
Project Summary – Overview of Finding and Conclusion
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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SECTION 3 – PERFORMANCE: SPACE
CONDITIONING TECHNOLOGIES FOR
HAWAII
This section discusses generic performance of four basis
space conditioning technologies used in Hawaii. There
four technologies are as follows: (A) Natural ventilation,
(B) Natural ventilation (with mechanically induced
indoor air movement), (C) Mechanical ventilation, (D)
Full, standard HVAC
SECTION 4 ‐ EVALUATING IEQ
PERFORMANCE FOR SPACE CONDITIONING
APPLICATIONS
This section evaluates and ranked the performance of
the four space conditioning technologies presented in
Section 3 and compared them with the proposed LDAC
technology, regarding Indoor Environmental Quality
(IEQ) and energy saving potential.
SECTION 5 – INDOOR ENVIRONMENTAL
REQUIREMENTS FOR SCHOOLS
This section discusses specific application of the
proposed LDAC technology unit for schools. Schools
have a high requirement for high indoor environmental
quality since children and young adults have a higher
susceptibility to problems arising from unhealthy indoor
conditions. This section provided a summary of basic
requirements for a high‐quality learning environment.
SECTION 6 – PREPARING VISITS TO
REPRESENTATIVE SITES
This section presents efforts which were taken by the
project team to engage stakeholders of educational
facilities that were considered candidate locations for
the installation of a pilot liquid desiccant
dehumidification unit for space conditioning.
SECTION 7 – CONDUCTING VISITS TO
REPRESENTATIVE SITES
Several site visits were conducted to obtain information
about different building aspects and space conditioning
technologies, which are of importance to the proposed
innovative hybrid space systems with liquid desiccant
dehumidification.
Main Conclusions
Achieving good indoor environmental quality (IEQ) is an important concern in modern building design.
Since humans spend about 90% of their time indoors, the indoor environment must provide healthy and
productive conditions to avoid risks to the occupants. Figure 2.5 indicates important elements of the
indoor environmental experience. The different IEQ elements were placed into three categories based
on their impact on HVAC design.
Project Summary – Overview of Finding and Conclusion
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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These three categories and the individual characteristics therein were assigned different weights for a
ranking procedure of the four conventional space conditioning technologies PLUS the new proposed
LDAC technology. The ranking assigned to the five space conditioning systems, four conventional
technologies plus the LDAC, determined their performance levels when considering both IEQ and energy
saving. Figure 2.6 shows the results of the ranking for the Systems A through E, which are defined as
follows:
Conventional space conditioning technologies
System (A) – Natural ventilation System (B) – Natural ventilation (with mechanically induced indoor air
movement):
System (C) – Mechanical ventilation:
System (D) – Full, conventional HVAC:
NEW – proposed
system
System (E) – Proposed LDAC technology, decoupled liquid desiccant
dehumidification with energy efficient sensible cooling
Figure 2.5:
Interrelationship of
aspects of IEQ, IEQ
aspects grouped
into three
categories with
different ranking
weights
Project Summary – Overview of Finding and Conclusion
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Figure 2.6 : Overall ranking scores of System A through E The overall score indicates the level of performance when both providing high energy savings and good IEQ are considered in a comprehensive assessment framework.
With energy saving and IEQ being the two main parameters in the ranking methodology, a sensitivity
analysis was performed that indicated how the five space‐conditioning systems A though E rank as the
importance of energy saving and IEQ improvements were changed relative to each other. Figure 2.7
shows the ranking scores of Systems A through E with different importance of IEQ and energy savings.
The results of the sensitivity analysis indicate that the proposed LDAC technology performs well over the
entire range of varying importance of energy savings and IEQ.
Figure 2.7 Relationship between the contribution of energy savings potential to overall ranking score
0%
20%
40%
60%
80%
100%
0% 20% 40% 60% 80% 100%
Overall ranking score [%]
Contribution in % of energy to overall ranking
Importance of energy savings
Importance of Indoor Environmental Quality
HighLow
LowHigh
System B: Nat. Ventilation with internal fans
System C: Mechanical
venti lation (ducted)
System E: Proposed hybrid system
System D Ful l
conventional HVAC
System A: Only
natural ventilation
Project Summary – Overview of Finding and Conclusion
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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Deliverable 3summarizing Project Task 3: "Identification of best system integration " "Assessment of Liquid Desiccant Dehumidification
Systems and Supporting Thermal Technologies and
Concept Designs with Emphasis on Application Potential
in Hawaii "
The main objective of this report was to identify the
best system integration of decoupled dehumidification
and sensible cooling technologies. The best integration
was determined based on general application potential
in Hawaii and for the specific pilot installation.
EXECUTIVE SUMMARY AND
RECOMMENDATIONS
SECTION 1‐ BENEFITS OF DECOUPLING
LATENT AND SENSIBLE HEAT REMOVAL
This section discusses benefits of decoupling sensible
and latent heat removal. Important basic processes and
properties of the process of decoupling sensible and
latent heat removal ‐ cooling and dehumidification are
described.
SECTION 2 ‐ CHARACTERISTICS OF LIQUID
DESICCANT BASED SPACE CONDITIONING
This section reiterates the process of liquid desiccant
dehumidification, and pointed out the basic differences
and advantages of desiccant dehumidification over
standard cooling based dehumidification.
SECTION 3 ‐ ASSUMPTIONS OF OUTDOOR
AND INDOOR CONDITIONS FOR DESIGN
CONCEPT ANALYSIS
This section describes basic outdoor and indoor
environmental and thermal conditions that were used
for the subsequent design concept analysis and
illustrative case studies.
SECTION 4 ‐ ESTABLISHING THE ENERGY
AND MASS BALANCE OF THE DESIGN
CONCEPT LD SYSTEM
This section presents a simplified basic energy and mass
balance assessment for the design concept of the LDAC
system. The design concept analysis provides the basic
design data to determine feasibility and generic
Project Summary – Overview of Finding and Conclusion
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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performance of the peripheral sensible cooling and
heating technologies.
SECTION 5 ‐ SELECTING CANDIDATE
PERIPHERAL COOLING AND HEATING
TECHNOLOGY TO SUPPORT THE LD CORE
SYSTEM
This section describes the scope of the cooling and
heating technologies that can be considered as
peripheral technologies in support of the core liquid
desiccant (LD) system.
SECTION 6 ‐ INTEGRATED LIQUID
DESICCANT AND SENSIBLE COOLING
TECHNOLOGIES – CANDIDATE
TECHNOLOGIES FOR SINGLE BUILDING
This section investigates the performance
characteristics of various sensible cooling and heating
technologies which serve as “peripheral” thermal
systems in support of the LD “core” dehumidification
system.
SECTION 7 – EVALUATING CANDIDATE
PERIPHERAL TECHNOLOGIES AND
RANKING OVERALL SYSTEM
PERFORMANCE
This section describes 24 alternative combinations of LD
“core” dehumidification system and different sensible
cooling and heating peripheral systems. A quantitative
assessment of their performance was determined by
using a 2,400‐sqft. sample classroom space. The
performance was ranked, and a risk‐versus benefit
analysis was performed to determine the best among
the 24 alternatives investigated.
SECTION 8 – RECOMMENDED SELECTION
OF PERIPHERAL THERMAL TECHNOLOGIES
AND TEST SYSTEMS
This section describes the best three system
configuration based on the performance analysis
performed in Section 7.
Main Conclusions:
Figure 2‐8 illustrates the overall process concept of the proposed hybrid LD based space conditioning
system. The liquid desiccant (LD) dehumidification “core LD system” consists of an absorber (also
conditioner) and a desorber (also regenerator). The core LD system requires peripheral sensible cooling
and heating, as well as several other support functions.
The components depicted in Figure 2‐8 are:
Sensible cooling ‐ heat sink: either an electrically driven conventional vapor compression (VP)
chiller or a thermally driven adsorption chiller
Sensible cooling ‐ space cooling technologies: different technologies to capture indoor sensible
cooling loads and convey it to the heat sink. These technologies include fan coil unit (FCU),
active chilled beams (ACB), passive chilled beams (PCB) and chilled ceiling (CC). In addition,
Project Summary – Overview of Finding and Conclusion
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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ceiling fans are considered which provide an additional perception of sensible cooling to
occupants.
Heating, for desiccant regeneration, including: Solar thermal systems, fuel‐based boilers and
combined heat and power (CHP) are considered.
Energy storage, in the form of hot water storage and storage of concentrated desiccant solution
Energy recovery, in form of evaporative cooling using the dry discharge air and membrane based
enthalpy recuperation.
Figure 2.8: Work process of the integrated liquid desiccant (LD) dehumidification with supporting sensible support functions Sensible support functions are referred to in this report as “peripheral thermal technologies”
Twenty‐four (24) system alternatives were defined and their performance was assessed. A performance
assessment resulted in a ranking of alternatives based on risk versus benefit, as shown in Figure 2.9.
Main parameters were “significance”, the value the alternative would offer to applications in Hawaii;
and “practicality”, the feasibility of using the alternative for the pilot tests. Figure 2.10 illustrates the
significance versus the practicality ranking matrix.
Project Summary – Overview of Finding and Conclusion
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Figure 2.9: Summary of pertinent results of the risk versus benefit assessment
Figure 2.10: Results of the practicality versus significance assessment for technologies – Table
Note: The energy recovery technologies E‐1 through E‐3 are not included in ranking
Based on the performance of the 24 alternatives, three candidate configuration of LD core technology
and peripheral cooling and heating technologies were selected for the pilot installation. Since the initial
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
LD‐core system X X X X X X X X X X X X X X X X X X X X X X X X
Peripheral thermal technologies
A Cooling ‐ heat sink:
A‐1 VP chiller water cooled X X X X X X X X X X X X
A‐2 Adsorption chiller water cooled X X X X X X X X X X X X
B Cooling ‐ space cooling techno
B‐1 Fan coil unit (FCU) X X X X X X X X
B‐2 Active Chilled Beam (ACB) X X X X X X X X
B‐3 Passive Chilled beam (PCB) X X X X X X X X
B‐4 Chilled ceiling (CC)
C Sensible heating
C‐1 Solar system X X X X X X X X X X X X
C‐2 Boiler (conventional and biofuel) X X X X X X X X X X X X
D Energy storage:
D‐1 Hot water storage X X X X X X X X X X X X
D‐2 Concentrated desiccant store. X X X X X X X X X X X X
E Energy recovery and CF redits:
E‐1 WBT recovery X X X X X X X X X X X X
E‐2 Membrane ERV (NA)
E‐3 Ceiling fans (CF) X X X X X X X X X X X X
Peripheral thermal technologies
Cooling ‐ heat sink: A‐1 A‐1 A‐1 A‐2 A‐2 A‐2 A‐2
Cooling ‐ space cooling techno B‐2 B‐3 B‐3 B‐1 B‐2 B‐3 B‐3
Sensible heating C‐1 C‐1 C‐2 C‐1 C‐1 C‐1 C‐2
Energy storage: D‐1 D‐1 D‐2 D‐1 D‐1 D‐1 D‐2
Energy recovery and CF redits: E‐1 E‐1 E‐1 E‐1 E‐1 E‐1 E‐1
3 2 1 4 3 1 2
Using VC‐chiller Using adsorption chiller
System configuration ‐ peripheral thermal technologies supporting the LD‐core
Core
Category
50%/50%
% value rankrank
points% va lue rank
rank
points% va lue rank
rank
points
A‐1 59% 3 7 77% 2 8 41% 5 0
A‐2 54% 4 6 46% 7 3 63% 3 0
B‐1 46% 7 3 57% 4 6 35% 6 0
B‐2 48% 6 4 53% 6 4 44% 4 0
B‐3 84% 1 9 94% 1 9 75% 2 0
C‐1 66% 2 8 45% 8 2 86% 1 0
C‐2 53% 5 5 75% 3 7 32% 7 0
D‐1 17% 9 1 24% 9 1 10% 9 0
D‐2 40% 8 2 56% 5 5 24% 8 0
E‐1 N/A N/A N/A
E‐2 N/A N/A N/A
E‐3 N/A N/A N/A
20%/80%
Importance of practicality larger
than significance criteria
Practicality/Significance Ratio:
Importance of practicality equal
to significance criteria
Importance of significance larger
than practicality criteria
80%/20%
A‐1 VP chiller water cooled
A‐2 Adsorption chiller water cooled
B‐1 Fan coil unit (FCU)
B‐2 Active Chilled Beam (ACB)
B‐3 Passive Chilled beam (PCB)
C‐1 Solar system
C‐2 Boiler (fuel)
D‐1 Hot water storage
D‐2 Concentrated desiccant store.
E‐1 WBT recovery
E‐2 Membrane ERV (NA)
E‐3 Ceiling fans
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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test will be carried out in a lab‐controlled environment, which has unique characteristics that may differ
from general application potential, a candidate system configurations emerged and was selected for the
initial test in the lab. Figure 2.11 shows the basic diagram of the selected system configuration:
Figure 2.11: Proposed test system for the Test system A represents a conservative approach to testing, since it uses conventional VC‐chiller and on‐demand heat source (boiler). The energy storage is optional, though testing would add valuable data.
Conditioned space
(C) Heating technologies:
Solar water heating
(D) Energy storage:
Hot water storage
Liquid Desiccant (LD) core
(A) Cooling – heat sink:
Conventional VC HVAC
Cooling tower
(E) Energy recovery
WBT energy recovery
Sensible Cooling
(B) Space cooling technologies
• Passive chilled beam (PCB)
• Ceiling fan (CF)
Project Summary – Overview of Finding and Conclusion
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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Deliverable 4 summarizing Project Task 4: "Design of Test Set‐up in Project Phase II" ""Design Study of a Packaged Liquid Desiccant (LD)
System in a Test Facility to Carry out a Test Program
under Lab Conditions and Subsequent On‐site Test
Operation of the LD System”"
The main objective of this report was to present the
preliminary design of a liquid desiccant air conditioning
(LDAC) system which will be used for air
dehumidification application tests in a lab controlled
environment (Project Phase II/A). The basic premise of
testing a liquid desiccant dehumidification system as
part of an advanced HVAC system is to prove that the
LD dehumidification technology will provide tangible
benefits regarding energy savings and providing a high
quality indoor environmental quality (IEQ).
EXECUTIVE SUMMARY AND
RECOMMENDATIONS
SECTION 1 ‐ BENEFITS OF LDAC
TECHNOLOGY FOR HAWAII
This section provides qualitative and quantitative
assessments of the value proposition provided by the
proposed LDAC system to Hawaii. The discussion
presented in this section stresses the importance of
considering both indoor environmental quality and
energy savings when designing HVAC systems that
comply with Hawaii’s sustainability goals. High indoor
environmental quality (IEQ) is an important
underpinning for the more comprehensive indoor
wellness and comfort conditions in high performance or
“green” building.
SECTION 2 ‐ DESCRIPTION OF THE LDAC
TECHNOLOGY USED FOR PILOT TESTS
This section describes the liquid desiccant technology
that will be used for the present project. While liquid
desiccants have been used for specific drying and
dehumidification applications for several decades, the
use of liquid desiccants in generic HVAC systems is a
Project Summary – Overview of Finding and Conclusion
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rather recent and still innovative technology. This
section assesses the energy costs and the financial
benefits for companies of increased IEQ conditions,
realized through the proposed LDAC technology.
SECTION 3 ‐ TESTING OF THE LDAC SYSTEM
IN PROJECT PHASE II
This section describes the two parts of Project Phase II,
Part A and B, during which the performance pilot
installation of an LDAC will be tested; first in a lab
controlled environment (Phase A) and then in a
regularly occupied space (Phase B).
SECTION 4 ‐ TESTS OF PHASE II/A INITIAL
“SHAKE DOWN” TESTS IN UHM MARINE
CENTER
This section presents the preliminary design of the
system installation for the initial system test in the lab‐
environment of the UHM Marine Center at Pier 35.
SECTION 5 ‐ TESTS OF PHASE II/B ‐ PILOT
INSTALLATION AT LOCATION TBD
This section describes objectives and plans for Project
Phase II/B. During Phase II/B the LDAC unit will be
installed at a test location, e.g. indoor space, whose size
and space conditioning requirements will match the
LDAC unit that was used and tested in Phase II/A.
Main Conclusions:
The performance of “green buildings” has been typically quantified by the scope of external environmental impact, and especially energy consumption. The emergence of wellness and healthy building standards have introduced a new form of primary internal performance metrics, where financial benefits of more healthy and productive buildings can be assessed.
Especially in hot, humid Hawaii, savings both in terms of energy and healthy and productive buildings are valued and the projected LDAC system can realize both. This report quantifies the projected energy savings and IEQ and wellness financial benefits using an example 8,000‐office space. Figure 2.12 compares the energy performance of a standard HVAC system and the proposed LDAC system, where the proposed LDAC system provides twice the ventilation air flow rate than the standard HVAC. Figure 2.12 indicates that the LDAC provides approximately a 30% savings relative to the standard HVAC. Figure 2.13 compares equivalent carbon emissions of the proposed LDAC system and a standard HVAC, both with vapor compression chillers the sensible heat sink. Here carbon emissions are reduced by about 40% with the LDAC system. Looking forward, when using thermal chillers as sensible heat sinks, the carbon equivalent savings increase to more than 80% relative to standard HVAC.
Project Summary – Overview of Finding and Conclusion
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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Figure 2.14 presents the combined savings of energy and IEQ and wellness related increases in
employee productivity and reduction in health risk. Figure 2.14 exemplifies that the financial benefits
derived from increased IEQ and wellness greatly surpass the financial benefits of energy savings with
96% of the savings derived from improved IEQ and 4% from energy savings .
The report provides the design documentation of the preliminary design for the pilot test set‐up during
Project Phase A.
Figure 2.12: Comparison of energy performance
Ths figure suggests that energy costs savings of about 30% can be anticipated under the assumed conditions.
Figure 2.13: Reductions in equivalanet carbon emissions.
Percentage comparison of baseline carbon equivalent emission between three HVAC systems: 1. Proposed LDAC with vapor
compression chiller 2. Standard HVAC 3. Proposed LDAC with thermally
driven adsorption chiller
58%
100%
17%
0%
20%
40%
60%
80%
100%
1. Proposed LDACsystem, with
vapor comprestionchiller
2. Standard(baseline) AC
3. Most efficientLDAC system
all solar
Carbon Dioxide Equivalent [% of baseline]
Project Summary – Overview of Finding and Conclusion
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RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
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Figure 2.13: Comparison of energy savings and increased revenues based on productivity gains through higher IEQ and wellness
The image illustrates how potential revenue gains compare to the projected energy savings. The potential revenue gains are through increased productivity.
Project Summary – Overview of Finding and Conclusion
PROJECT SUMMARY ‐ POWER POINT PRESENTATION
RCUH P.O. #Z10143891 Project Deliverable No. 5: Project Summary
Hawaii Natural Energy Institute Sustainable Design & Consulting LLC
November 27, 2017 Page 43
PROJECT SUMMARY ‐ POWER POINT PRESENTATION
The following is a power point presentation which summarizes the project work and the main conclusions and recommendations.
PROJECT SUMMARY PRESENTATION
THE GROWING INDOOR HUMIDITY CHALLENGE OF BUILDINGS AND
STRATEGIES TO SOLVE THEM
Preparing a Pilot Installation in Hawaii of Using Liquide Desiccant Dehumidification in HVAC to Avoid Indoor Humidity Problems and Improve
Indoor Air Quality while Saving Energy
Sustainable Design & Consulting LLC
November 27, 2017
Hawaii Natural Energy Institute
Manfred J. Zapka, PhD, PE (1)
James Maskrey, MEP, MBA, Project Manager (2)
(1) Sustainable Design & Consulting LLC, Honolulu, Hawaii(2) Hawaii Natural Energy Institute, Honolulu, Hawaii
ACKNOWLEDGEMENTS
This project is funded by the Hawaii Natural Energy Institute under grant no. N00014‐14‐1‐0054 from the Office of Naval Research. The authors would like to thank both HNEI and ONR for the opportunity to pursue explore the potential for this technology. The authors believe that desiccant cooling applications can be a significant contribution increasing the energy efficiently of building conditioning, providing a better humidity control and foster the implementation of more environmentally friendly ways to provide better occupant indoor environmental quality.
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Synopsis:The Risks of Green Building – As buildings become more energy efficient and sealed from
the outdoor environment, increased humidity and related problems become the next challenge of green buildings
The Problem with standard HVAC – Cannot effectively provide cool temperatures and accurately control humidity need to use different HVAC strategies and technologies for hot and humid climate of Hawaii
The Solution ‐ Decoupling (separating) sensible from latent cooling loads, which is impossible for standard HVAC
The Technology of choice – Innovative “low‐flow” liquid desiccant HVAC systems ‐ LDAC
The Benefits of LDAC to the Environment ‐ Significant energy savings and reduced carbon emissions
The Benefits of LDAC to Occupants, Companies and Building Owners ‐ Significant financial benefits from improved Indoor Environmental Quality which saves health related costs and increases work productivity
The Conclusion ‐ Hawaii needs new HVAC technologies like the proposed LDAC as we pursue meeting our important energy goals and creating more healthy and productive buildings at the same time.
Pathways ‐ Install and test a pilot LDAC system in Hawaii, first in a lab controlled environment, and then in a regular conditioned space.
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Energy efficiency and smart migration to renewables is essential for Hawaii.
Hawaii has made good progress in decreasing energy consumption
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Credit: Howard Wiig, Energy Office of Hawaii
The Problem: While we are getting very good at saving energy in buildings we are not paying enough attention to humidity related problems.
Article from 2009
Energy experts have been pointing to several problems of Green Buildings, one of which are humidity related problems. All of them are solvable … with the right approach
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Energy Usage Index (1975 use = 100%)
Energy Codes are main drivers in achieving energy conservation …..
Heat gain in building will continuously decrease as building envelopes improve, reducing energy use.
2017
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
EXTERNAL AND INTERNAL SENSIBLE HEAT GAIN IN BUILDINGS
We need to remove heat gain form indoor spaces to provide good thermal comfort … the less heat the more energy efficient
Space conditioning
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Shading windows
HOW WE CAN REDUCE HEAT GAIN: Shading of windows
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
HOW WE CAN REDUCE HEAT GAIN: High performance windows
High performance windows
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
HOW WE CAN REDUCE HEAT GAIN: Add Wall insulation to decrease conduction gains
Wall insulation
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
HOW WE CAN REDUCE HEAT GAIN: Add effective envelope sealing to decrease infiltration
Sealing envelope
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
HOW WE CAN REDUCE HEAT GAIN: Add cool roof designs and insulating attics
Cool roofs Insulating attics
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
HOW WE CAN REDUCE HEAT GAIN: Energy efficient lighting and appliances / equipment
Energy efficient lighting
Energy Star appliances and equipment
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
How far should we go to lower the energy use in buildings?
Super insulated house with small windows ?????
?
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
INDOOR ENVIRONMENTAL QUALITY (IEQ) AND WELLNESS are evolving
as a important metrics for high performance buildings … supplementing
the prevailing metric ‐ ENERGY EFFICIENCY.
QUALITY (IEQ) AND WELLNESS
CUTTING ENERGY USE
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Fact: Creating healthy and productive indoor spaces, with high
Indoor Environmental Quality, using conventional building
technologies will increase energy consumption
Increased ventilation
Increased HVAC
Increased reheat
Increased glazing to provide views and daylight
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Facts:
• New technologies and operational approaches are required to
create BOTH energy efficient AND health and productive
buildings.
• For Hawaii innovative HVAC technology can offer BOTH good
thermal comfort and good indoor air quality in an energy
efficient way.
800 pound Gorilla in the room .. for hot and humid climate in Hawaii
Humidity Humidity
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
0
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Sensible or Latent Heat [BTU
/h]
Time scale (arbitray)
Sensible Heat Latent Heat
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Latent Heat Ratio [LHR]
Sensible Heat Ratio [SHR]
Time scale (arbitray)
SHR LHR
As the sensible cooling decrees the latent load increases proportionally
Creating challenges for standard HVAC
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
The ratio of sensible and latent loads are changing significantly
Low SHR cooling loads create problems with conventional HVAC technology as they cannot efficiently mitigate humidity related problems, especially in Hawaii’s hot and humid climate .
Mold..!!
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Most Effective Approach to Solve the Growing Humidity Problem – “Decouple Cooling Loads”
Decouple sensible and latent cooling load
Standard HVAC operation with simultaneous sensible and latent cooling load removal
Advanced HVAC which decouple sensible and latent load removals. >>>>
>>>>
LATENT COOLING
SENSIBLE COOLING
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Conventional AC with cooling based dehumidification
Problem, cooling based dehumidification cannot be separated from sensible cooling
Cannot be decoupled
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Typical problems with conventional AC overcooling and insufficient dehumidification
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Relative Humidity
Organisms ↓ 0 10 20 30 40 50 60 70 80 90
Bacteria
Viruses
Fungi
Mites
Allergic Rhinitis & Asthma
Respiratory Infections
Chemical Interactions
Ozone production
Optimum level of R
H
Levels of activity of harmful organisms and chemical interactions are directly affected by indoor RH level
The value of 45% RH has been mentioned in the literature as optimum indoor RH
Health risk factors when controlling for indoor relative humidity (RH)
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
• Present research work at the UHM (HNEI) to use liquid desiccants for dedicated humidity control
• Utilizes energy efficient hydronic sensible cooling technologies such as chilled beams and radiant cooling without condensation problems.
• Liquid desiccant technology has been used for many decades… but not for conventional HVAC systems.
• Innovative “Low flow” desiccant technology is a recent development and is suitable for regular HVAC applications, it is “a rapidly evolving technology”.
Ongoing HNEI Research Work in Advanced HVAC
Building on previous technology development sponsored by NREL
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Basic processes of liquid desiccant dehumidification
Different from standard cooling‐based dehumidification, liquid desiccant dehumidification does NOT require cooling air to drop below dew point.
Three main process steps in desiccant dehumidification
Sorption process, water vapor migrates from the
humid air to the desiccant. Water vapor pressure is higher in the moist air
Desorption process ‐humidity migrates from the
desiccant to the hot scavenging air. Water vapor pressure is
higher at the desiccant surface
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Conventional liquid desiccant dehumidification processes
For several decades ‐ Proven and effective dehumidification technology for specialized industrial and commercial applications
It works well – but has not been widely used in general HVAC applications
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Example of a packed columns liquid desiccant system
Several Commercial installations
New Low‐flow liquid desiccant technology developed by AIL Research
AILR low flow" LD dehumidifier with three main components: conditioner, regenerator and interchange heat exchanger (IHX)
The AILR patented absorber and regenerators design. Cooling tube are imbedded into an evaporative medium
Innovative “Low‐Flow” liquid desiccant dehumidification processes developed for energy efficient use in HVAC
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Options for energy efficient sensible cooling technologies
Fan coil unit
Chilled (radiant) ceiling
Active chilled beam Passive chilled beam
Liquid Desiccant Air Conditioning (LDAC) systems need decoupled sensible cooling technology
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Sensible heat
removal = Cooling
Latent heat removal =
Dehumidification
New LDAC Technology to be tested in Hawaii Decoupled sensible & latent cooling
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Best LDAC technology for Hawaii ‐ Using solar energy to achieve the largest energy savings and lowest carbon emissions
LDAC system
Sensible heat removal =
Cooling
Latent heat removal =
Dehumidification
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Psychrometric performance of LDAC and standard HVAC The standard HVAC requires 64.8 tons (54+10.8 tons) along PATH 1. The LDAC requires 43.2 tons along PATH 2; this is a saving of 33%
$30,000
$21,000
$9,000
$0
$10,000
$20,000
$30,000
$40,000
Conventional DX HVAC system;min. ventilation rate
Proposed LDAC system; doublemin. ventilation rates
Energy Costs / Savings
Energy costs Energy savings
Comparison of annual energy costs between a standard HVAC and the proposed LDAC system. The energy calculation was done for a sample 8,000‐sqft office.
Predicted energy savings of several AILR liquid desiccant systems reported by NREL
Energy savings of the LDAC system
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Lower carbon emissions from LDAC system compared to standard HVAC >>>>>>>>>>
58%
100%
17%
0%
20%
40%
60%
80%
100%
1. Proposed LDACsystem, with
vapor comprestionchiller
2. Standard(baseline) AC
3. Most efficientLDAC system
all solar
Carbon Dioxide Equivalent [% of baseline]
Photo credit: japantimes.jp
All‐solar LDAC achieves very high energy savings and carbon emissions reductions.
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Pilot Project in Hawaii using two basic (and decoupled) HVAC technologies:• AILR LDAC unit for precise dehumidification• Passive chilled beam for energy efficient sensible cooling
Test program in two Phases:• First Phase, testing of LDAC in a lab‐controlled environment • Second Phase, testing of LDAC in a regular, but demanding,
HVAC application
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Advantages of LDAC over standard HVAC• Separates (decouples) control of cooling and dehumidification
• Achieves significant energy savings
• Avoids overcooling and reheat of supply air
• Can use renewables for desiccant regeneration
• Mitigates humidity problems
• Allows for increased fresh air ventilation
• Offers improved Indoor Air Quality
• Increase Indoor Environmental Quality and “Wellness”
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Tangible financial benefits through IEQ and Wellness
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Harvard Healthy Building Program estimates ~ $6,500 per employees from increased productivity through increased ventilation and better indoor environmental quality.
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
$230,000
$9,000
$0
$50,000
$100,000
$150,000
$200,000
$250,000Cost Savings / Increased Revenue
96%
4%
0%
20%
40%
60%
80%
100%
Percentage of Cost Savings / Increased Revenue
Calculated energy cost savings
Calculated increased productivity through better IEQ and Wellness
Figure above: Comparison between calculated energy cost savings and reduced costs realized with better IEQ and wellness. The calculations are based on the following assumptions:
• 8,000‐sqft. office • 110 sqft. per person• Use conservative 50% of Harvard figure of $6,500 per person productivity gain and
less health risk = $3,350 per person
• Financial benefits of improved IEQ and wellness to companies and building owners exceed energy cost savings
• Improved Indoor Environmental Quality (IEQ) and Wellness have become marketable differentiators for buildings
The proposed LDAC system achieves higher IEQ while
saving energy
The proposed LDAC system achieves higher IEQ while
saving energy
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
THANK YOU
Manfred Zapka, PhD, PE, PrincipalCertifications: WELL AP, ENV SP, LEED‐AP, CEM, CEA
Sustainable Design & Consulting LLC, Honolulu, [email protected]
Project Summary Presentation by Manfred J. Zapka and James Maskrey, November 2017
Jim Maskrey, MEP, MBAAssociate Specialist, Hawaii Natural Energy InstituteSchool of Ocean and Earth Science and TechnologyUniversity of Hawaii at [email protected]
Sustainable Design & Consulting LLC
Hawaii Natural Energy Institute