Asia Pacific Research Initiative for Sustainable Energy ... Dehumidification...Sustainable Design &...

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


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


EXECUTIVE SUMMARY



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.


EXECUTIVE SUMMARY




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


EXECUTIVE SUMMARY




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.


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.






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.






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]


SHR LHR






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






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.






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.






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






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.






(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.






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.






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






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:






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.






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.






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






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]






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






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






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






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.






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.






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


PART 2: OVERVIEW OF WORK SCOPE OF PROJECTS DELIVERABLES 1 THROUGH 4




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






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.






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






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






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.






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.






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






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






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






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,






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.






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






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)






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






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.






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%





all solar







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 ‐ POWER POINT PRESENTATION




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


November 27, 2017


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.


Energy efficiency and smart migration to renewables is essential for Hawaii.

Hawaii has made good progress in decreasing energy consumption


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


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


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


Shading windows

HOW WE CAN REDUCE HEAT GAIN: Shading of windows


HOW WE CAN REDUCE HEAT GAIN: High performance windows

High performance windows


HOW WE CAN REDUCE HEAT GAIN: Add Wall insulation to decrease conduction gains

Wall insulation


HOW WE CAN REDUCE HEAT GAIN: Add effective envelope sealing to decrease infiltration

Sealing envelope


HOW WE CAN REDUCE HEAT GAIN: Add cool roof designs and insulating attics

Cool roofs Insulating attics


HOW WE CAN REDUCE HEAT GAIN: Energy efficient lighting and appliances / equipment

Energy efficient lighting

Energy Star appliances and equipment


How far should we go to lower the energy use in buildings?

Super insulated house with small windows ?????

?


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


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


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


0

0.2

0.4

0.6

0.8

1 2 3 4 5 6 7 8

Sensible or Latent Heat [BTU

/h]


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]


SHR LHR

As the sensible cooling decrees the latent load increases proportionally

Creating challenges for standard HVAC


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..!!


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


Conventional AC with cooling based dehumidification

Problem, cooling based dehumidification cannot be separated from sensible cooling

Cannot be decoupled


Typical problems with conventional AC overcooling and insufficient dehumidification


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)


• 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


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


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


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


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


Sensible heat

removal = Cooling

Latent heat removal =

Dehumidification

New LDAC Technology to be tested in Hawaii Decoupled sensible & latent cooling


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


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


Lower carbon emissions from LDAC system compared to standard HVAC >>>>>>>>>>

58%

100%

17%

0%

20%

40%

60%

80%

100%





all solar


Photo credit: japantimes.jp

All‐solar LDAC achieves very high energy savings and carbon emissions reductions.


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


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”


Tangible financial benefits through IEQ and Wellness


Harvard Healthy Building Program estimates ~ $6,500 per employees from increased productivity through increased ventilation and better indoor environmental quality.


$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


THANK YOU

Manfred Zapka, PhD, PE, PrincipalCertifications: WELL AP, ENV SP, LEED‐AP, CEM, CEA

Sustainable Design & Consulting LLC, Honolulu, [email protected]


Jim Maskrey, MEP, MBAAssociate Specialist, Hawaii Natural Energy InstituteSchool of Ocean and Earth Science and TechnologyUniversity of Hawaii at [email protected]



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