1

Hybrid Ventilation – Innovative Use of Renewable Wind Energy

Allan Ramsay

CSR Edmonds ( a business unit of CSR Building Products Ltd,

Sydney, Australia). Email – aramsay@edmonds.com.au

----------------------------------------------------------------------------------------------------------------

Abstract.

The use of natural ventilation systems to improve air quality and comfort in

buildings has been exploited for centuries. Over the recent past, as the issue of climate

change has gathered in importance and the costs of energy have escalated, there has

been a range of innovative attempts to apply the forces of natural ventilation – stack

effect and wind suction effect – to provide more sustainable buildings. These range

from solar chimneys, to mixed mode passive and mechanical to thermal chimneys with

mechanical boost. However, all such solutions lack total performance guarantee in

warmer climates, or are too reliant on energy intensive mechanical support, or

compromise natural operation by blockages to the net free ventilation throat area.

CSR Edmonds, Australia, with the assistance of ebm-papst, Germany, has made

a technological breakthrough, whereby natural forces and high energy efficiency

mechanical operation have been combined into a single hybrid product class without

any compromise to natural operation. This is a world first. The resultant hybrid ventilator

can operate freely in natural mode alone as a wind driven rotary ventilator or be

activated to mechanical operation where the turbine head acts as a centrifugal fan. The

natural forces continue to assist the performance in mechanical mode. The resultant

hybrid product class has extraordinary levels of energy efficiency in mechanical mode,

has virtually inaudible operation and can manage significantly higher pressure losses

than traditional passive systems. Its range of applications have extended from removing

heat from electronics, ventilating school classrooms, improving IAQ in community halls

and places of worship to removal of thermal load from factories, warehouses and data

centres. The breakthrough technology is still in its infancy and through further advances

in electronic commutating motor technology and control electronics has enormous

potential for providing energy savings across a large range of applications.

1. Introduction.

Ventilation, in its simplest terms, is the exchange of one parcel of air for another. It

commonly refers to the removal of stale, polluted or warm air and its replacement by air

of better quality. The process requires easy pathways for new air to enter an enclosure

and for the hot, stale air to be displaced. The requirement for adequate ventilation is

today part of nearly all building codes in advanced economies. It is widely recognised

as being essential for the maintenance of acceptable working conditions and a

safeguard of worker’s health.

2

The ventilation process requires a pressure differential for air, a fluid, to flow.

Natural, or passive, ventilation is ideally suited as an environmentally acceptable means

for creating this pressure differential using the available natural forces of temperature

(thermal effects) and wind to create air pressure differences that aid and direct the

movement of air through buildings. Passive ventilation can rely on pure stack effect

alone or a combination of stack and Bernoulli’s principle (wind suction).

Bernoulli’s principle uses wind speed differences to move air. It is a general principle

of fluid dynamics that the faster air moves, the lower its pressure. The low pressure if

induced at height can help suck air through a building. The advantage of Bernoulli’s

principle over the stack effect is that it multiplies the effectiveness of wind ventilation.

The advantage of stack ventilation over Bernoulli's principle is that it does not need

wind: it works just as well on still, breezeless days when it may be most needed. In

many cases, designing for one effectively designs for both, but various product designs

and architectural constructions can be employed to emphasize one or the other.

2. The Long History of Passive Ventilation.

For over one thousand years man has designed his place of abode to utilise the

ventilation concept. Examples include the naturally ventilated American Indian tepee,

wind catcher towers used throughout the middle east and ventilation chimneys used in

many fort designs typical of the 15th and 16th centuries and demonstrated perfectly

throughout the Gulf region, where they exploited the typical afternoon breezes flowing

from sea to land. These were all excellent examples of using renewable resources to

produce favourable living environments.

Fig 1. Typical wind tower to Fig 2. Portuguese fort, Oman showing wind capture afternoon breezes. chimneys.

These were also early examples of the use of the ‘free air cooling’ concept, often

referred to now as ‘night purge’. Over long cycle times, such as day and night, natural

ventilation can provide a degree of temperature stabilisation inside a large space.

During the day the sun heats buildings by radiation. The thermal mass of the building

will absorb heat. At night, the same buildings begin to cool by radiating their absorbed

3

heat into space. Wall and roof insulation can be used to lessen heat gain during the day

and to lessen heat loss at night.

3. Ventilation Design to Cater for Industrial Growth

As the industrial revolution gathered pace, and factories became equipped with

steam engines, boilers, forges and large labour forces, there became a need to reduce

the impact of heat load and smoke filled atmospheres on workers. Often health was not

the motive, more so a drive for higher worker productivity. Steam often condensed on

the underside of roofs in cooler climates and condensed on workers and machinery.

These impacts all led to the incorporation of elementary ventilation devices such as

holes in roofs with some form of elevated covering to restrain water ingress.

New ventilation designs such as the lantern or Jack roof came along and the design

of the saw-tooth roof with louvre openings on the vertical sections.

Fig 3. Jack Roof Concept. Fig. 4. Saw Tooth Roof Design with

Louvres.

These were typically used to cover large workshops and industrial plants. They

continued to flourish well into the 1930s although their functionality suffered from back

drafting when winds perpendicular to the structures drove into the louvre openings. This

often led to water ingress but more seriously hindered the escape of hot, polluted air.

Typically, if environmental conditions were suitable, hot, polluted air would rise and

depart from the openings under stack pressure at a rate defined by:

SI units

where:

Q = stack effect draft (draught in British English) flow rate, m3/s

A = flow area, m2

Cd = discharge coefficient (usually taken to be from 0.65 to 0.70)

g = gravitational acceleration, 9.81 m/s2

h = height or distance, m

4

Ti = average inside temperature, K

To = outside air temperature, K

Jack Roof designs gradually gave way to purpose designed gravity ventilators typically

represented by ridge ventilators and slope mounted gravity vents.

Fig. 5 . Typical ridge ventilator design.

While ridge vents were characterised by much larger effective aerodynamic areas,

and hence flow rate capacities, they remained largely dependent on temperature

differential for performance. When ambient temperatures were typically very high,

unless a factory generated significant internal heat there would be little flow. Night

purge potential was often significantly higher where thermal storage retained daytime

heat in the factory and resulted in radiated heat during the evening. Suction effect, due

to wind pressure had only minor impact on the performance of these early designs

However, regardless of the use of renewable resources to improve factory

environments, the performance of gravity vents could not be relied upon by specifiers

nor could flow rates be accurately determined. Methods for assessing flow rate

performance were generally vague and rarely were coefficients of discharge

determined. These natural ventilators were ‘slaves’ to environmental conditions and

could rarely meet demand peaks. This characteristic, plus the move to generally flatter

roof profiles and the corresponding requirement for distributed ventilation rather than

centralised, has generally seen the slow demise of the ridge ventilator.

The first competitor to the ridge ventilator came from the use of mechanical

ventilation, both axial and centrifugal designs. Mechanical vents quickly took control of

the ventiation market because they:

Offered predictable performance with flow rates that could be accurately

determined through construction of individual flow curves using ISO

standards.

Power costs were generally low at the time around much of the developed

world. Carbon emissions were also not a matter of global concern.

5

Mechanical engineers were well-schooled in the selection and performance

of mechanical vents whereas natural ventilation was a subject inadequately

addressed at many universities.

There was scant data available about the performance of passive ventilators

against pressure loss..

There were no accepted international standards for measuring the

performance of passive ventilators given that effective aerodynamic area was

crucial to performance but procedures for assessing the coefficient of

discharge were sadly lacking.

4. The Move to Rotary Wind Ventillators.

The father of wind driven ventilators is generally considered to be S.J. Savonius [1]

who designed the S Rotor Ventilator.

Fig 6. Typical S Rotor Ventilator

Edmonds Pty Ltd commenced to manufacture the S Rotor Ventilator in 1934 in

Sydney, Australia. The S Rotor Ventilator can still be seen today in Australia on old

picture theatres, rural halls and small family workshops. The S Rotor was followed in

1946 by the launch in the USA by Lomanco Inc. of the ‘onion’ shape ventilator,

Whirlybird®.

Wind driven turbines were a significant advancement compared to early natural

ventilation designs as they sought to continue to harness stack effect but aimed to

enhance induced suction by the increasing the magnitude of the Bernoulli effect.

6

Fig 7. The driving forces of stack and Bernoulli principle

Both Whirlybird and the S Rotor Ventilator were sparingly used on large factories

due to their perceived low flow rates compared to large ridge vents and slope mounted

static vents. Their throat areas were typically less than 0.07m². This opportunity was

seized by both Western Ventilation (USA) and Edmonds Pty Ltd (Australia) who were

the leading organisations to design large scale industrial wind driven turbine ventilators.

Western focused on the enlargement of the onion shape vent to throat sizes of 1000mm

while in the late 1980s Edmonds developed the world’s first vertical vane vent design

eventually up to size 900mm throat.

Fig 8. Edmonds’ vertical vane Hurricane™

ventilator

7

These developments saw large wind driven ventilators largely replace the

traditional ridge ventilator in many industrial applications due to their perceived ability to

function on both stack and enhanced wind suction effects and provide distributed

ventilation. If conditions for stack operation were suboptimal then wind energy afforded

a further source of natural drive.

Large diameter wind ventilators quickly grew in popularity in countries where

power costs were significant and/or unreliable and in environments where high ambient

temperatures reduced the life of motors in mechanical vents. The Gulf region and sub-

continent met one or more of these criteria and have shown tremendous growth in the

use of large wind driven ventilators.

The 2000s saw growing world concern with rising levels of atmospheric carbon

dioxide and their predicted impact on future world temperature increases. Many

countries put in place standards to improve efficient use of energy and/or to increase

the share of renewable energy resources in the power generation mix. It was expected

that wind driven ventilators would replace much of the use of mechanical ventilators for

general factory and warehouse ventilation. However, this trend faltered due to:

The move to use of higher efficiency electronic commutating motors in

mechanical ventilators.

The lack of any world accepted standard for assessing the flow rate performance

of wind driven ventilators. For mechanical consultants that are expected to certify

project performance and to meet ventilation performance standards, this

remained an area of considerable concern. Flow rate claims by many market

participants for identical throat ventilators often differed by factors of 3-5.

The lack of any published studies showing flow rate performance curves of wind

driven ventilators as a function of wind speed and pressure loss.

The general view that wind driven ventilators at wind speeds 0-20km/hr are

unlikely to perform against a pressure loss as low as 3 - 5Pa.

5. The Advent of AS/NZS 4740 (2000).

The natural ventilation industry in Australia was acutely aware that mechanical

consultants were struggling with the certification of projects using wind driven

ventilators. Reliable field-testing of natural wind rotary ventilators for flow rates is very

difficult because of unsteady conditions and the need to interfere with air flow in the

throat of the ventilator. Test requirements include a steady wind speed, precise low

differential pressure measurements and rates of air extraction, all determined to a high

degree of confidence.

As a result, AS/NZS 4740 – Natural Ventilators Performance and Classification [2]

was published by the Australian Standards Association It was the first such Standard

for Natural Ventilators in the world and covered:.

- Types of natural ventilators,

8

- Performance testing methods for air flow rates, wind loading and rain

resistance,

- Calculations for pressure and air flow rates,

- Flow and discharge coefficients,

- Effective aerodynamic area.

This Standard, AS/NZS 4740:2000 “Natural ventilators – Classification and

Performance”, classifies four types of natural ventilator:

- Type 1. Grilles, louvered cupola,

- Type 2. Static, as ridge vents, hoods, cowls, gravity types,

- Type 3. Swivelling - elbows, birds or rotating bird cowls,

- Type 4. Turbine, (wind driven).

Flow through an opening or a natural roof ventilator is given by the Standard as:

windstack

combined

PPFQ

2

Where,

combinedQ = combined effects of stack and wind siphonage (m3/s),

F = effective aerodynamic area (m2) = Cd x A (throat area of ventilator).

stackP = pressure difference (at top) due to inside heating (Pa),

windP = Pressure difference (at top) due to wind siphonage (Pa) (requires .

. determination of coefficient of flow, Cf) = air density, usually taken as 1.2 kg/m3.

Fig.9. Original ventilator Test rig established by CSR Edmonds in accordance with AS/NZS 4740.(2000).

9

Edmonds, with the assistance of personnel from University of Technology

Sydney, set up the test procedure described in AS/NZS 4740. Results revealed flow

rates significantly less than what was at that time universally promoted by many

manufacturers of natural rotary wind ventilators. Examples of test results appear below:

Vent Throat Size, mm.

Coefficient of Discharge

Coefficient of Flow

Flow rate at V = 3m/sec m³/hr

Flow rate at V = 6m/sec m³/hr

400mm 0.704 0.237 646 742

500mm 0.728 0.217 1040 1160

700mm 0.540 0.120 1551 1611

900mm 0.630 0.174 3383 3596

Fig 10. Flow rates for Hurricane™ rotary ventilator tested to AS/NZ4740

Stack pressure = 2.8903Pa

While the results were disappointing to some, they were far more believable when

compared to the flow rate of many powered vents of similar diameter. The general flow

capacities were also later supported by work carried out by Khan et al at University of

Nottingham [3] on the smaller size ventilators.

It is well recognised that while AS/NZS 4740 (2000) does apply the well-known

equations of fluid mechanics it cannot possible replicate the constant varying conditions

encountered in the field nor does it take into account viscous effects (also called

‘Reynold effects’). Nevertheless it does enable direct comparisons of rotary vent

designs under standard conditions and provides at least a scientific basis for designing

rotary ventilation schemes for projects.

The results of studies undertaken by A. Revel for Insearch Limited – a research

arm of University of Technology, Sydney [4] - showed that the vertical vane vent design

generally has a far superior coefficient of flow compared with the older onion shape but

that flow coefficients are typically less than 0.3. Discharge coefficients, depending upon

base type and internal blockages, can be as high as 0.8. Hence rotary vents are still

highly dependent on stack effect at low to medium (20km/hr) wind speeds. This

drawback later became one of the important catalysts for the development of the

vertical vane hybrid ventilator.

The other well-known deficiency of wind powered ventilators is their poor capacity to

perform against pressure loss at average wind speeds (defined as 8 – 16 km/hr for

most locations). Revolution rates for the larger size vents (600mm-900mm) will be

typically less than 70 rotations per second at average wind speeds and this is simply

too low to manage against pressure losses exceeding 3-5Pa. Projects which rely on

supply air entering through tight louvres are going to require huge banks of louvres to

reduce pressure loss to manageable levels for a rotary vent scheme to function

adequately. Where open doors are constantly available, with suitable net free area,

then projects should perform to expectation but such luxuries are often not available

due to security issues or, in the case of the Gulf Region, dust and sand ingress.

10

6. Solar Chimneys.

During the 1990s the concept of using natural ventilation induced by installation of

solar chimneys, became popular. The chimneys were often painted black to absorb

heat to raise internal air temperatures and hence increase stack pressure and

ventilation rates..

Fig. 11. Application of thermal chimney to

naturally ventilate a building.

Per Heiselberg [5] was one of the leaders in early design work on solar chimneys.

However, it soon became apparent that passive ventilation using solar chimney design

had drawbacks including:

Dust and insects entering a building.

The uncontrollability and unreliability of flow rates

Sensitivity to pressure drop from any restrictions to external ingress of supply air.

7. The Move to Hybrid Ventilation Systems.

The drawbacks inherent in solar chimney design led researchers to consider the

need to combine both passive ventilation and mechanical into a single system, the

so-called hybrid ventilation design. In hybrid ventilation mechanical and passive

forces are combined in a two mode system which is capable of operating in either

mode alone, or both modes simultaneously.

Fig. 12. The concept of hybrid ventilation

WIND +

STACK EFFICIENT

MOTOR +

11

The advantages of hybrid ventilation compared to mechanical alone include:

The capability to utilise natural forces when conditions allow, thereby

reducing energy usage.

A guarantee that indoor environmental conditions can be met at all times.

The capability to optimise the balance between indoor air quality, thermal

comfort, energy use and environmental impact in a truly sustainable manner.

Provision for offering intelligent and advanced ventilation solutions.

Compared with pure passive design, hybrid systems can ensure that ventilation

objectives are nearly always met, thus satisfying occupation health codes and providing

user satisfaction.

A popular early hybrid design involved the addition of an axial fan to the throat of

solar chimneys. If flow rate performance in passive mode was inadequate to meet IAQ

provisions and desired thermal comfort levels, the option existed to activate mechanical

mode. However, the pure existence of the motor and blades within the air stream of the

chimney causes a reduction in the net free area (Cd x A) thereby reducing performance

in passive mode. This reduction can easily reach 50% depending upon the level of

reduction in net free area. Thus the time the system may operate in passive mode

alone can be significantly reduced, which lowers the overall energy efficiency of the

combined system through compromise of passive performance.

8. Vertical Vane Hybrid Technology.

In 2004, CSR Edmonds released the first prototypes of a hybrid rotary ventilator

which had no reduction in net free area compared with the purely passive product.

Fig13 - Diagram from CSRs European patent showing

the innovative location of the motor in the Hybrid. [6]

The innovative step as defined in the patent consisted of the insertion of ‘a motor for

operation between a rotor connected to a wind driven ventilator and a stator

mounted to the structure’.

12

In practical terms, Edmonds simply took their Hurricane™ brand rotary wind ventilator

and inserted a motor in the head of the ventilator in accordance with the patent, such

that the motor also became the bearing system for the new ventilator.

Hurricane™ Rotary Ventilator EcoPower™ Hybrid Ventilator

Fig14. The transition from rotary wind ventilator to hybrid ventilator.

In keeping with the philosophy of energy efficiency, it was decided to use

electronic motor technology. ebm-papst (Germany) specifically modified a series of

motors for this new application to cover a range of hybrid vent designs. The motors

each had to be preset to a maximum capacity utilisation in order to keep operating

temperatures below maximum safety levels. It was also important that the motors

offered low resistance to natural operatrion such that the hybrid could operate as a

standard wind driven ventilator (i.e passive mode) with flow properties unaffected

compared to the vertical vane rotary design ventilator.

Fig.15. EC motor design used in vertical vane hybrid.

13

The electronic commutation (EC) motor technology itself was innovative creating

new advances to benefit original equipment manufacturers and end users. These

innovations included:

• The use of highly efficient DC motors that connect direct to AC mains, eliminating

the need for expensive and high risk installations.

• 100% noiseless speed control from any sensor input, BMS (Building Management

System) or internet access systems. The EC motor in the EP900 can operate in

isolation, while also logging its operation for later analysis.

• Input voltage range of 200 to 277VAC and 50/60 Hz. The ventilation performance

does not change; the motor is intelligent enough to identify the conditions and

adjust its performance accordingly.

Fig16. Vertical vane hybrid in mechanical mode.

The new hybrid technology represents the first time that unhindered hybrid

operation has been offered to the world in one product and not a system. The design

allows the wind turbine itself to be used as a centrifugal impeller when running in

powered mode using the direct drive capabilities of the EC motor. No separate fan is

required for the provision of mechanical ventilation. This utilises the best features of

each while eliminating their relative drawbacks. The drawbacks of previously existing

separate fan/natural vent combination units being blockage of the inlet throat by the fan

and impedance of the fan performance by the natural vent. Three product sizes have

been developed with 400mm, 600mm and 900mm throat diameters. Their properties

appear below.

14

Hybrid throat size (mm)

Exhaust rate m³hr (Δp=0)

Max. Power (W)

Max. running current (A)

Noise @3m dB(A)

Head weight kgs. .

Flow rate natural mode. V=3m/sec. Stack pressure = 2.89Pa (m³/hr)

400mm 2,400 68 0.26 46 7.6 727

600mm 4,250 116 0.47 49 14.4 1,274

900mm 10,000 260 1.21 45 30.0 Not tested

Fig.17. Properties and Performance for hybrid rotary ventilator.

(Tests carried out between CSR Edmonds and ebm-papst to relevant

standards).

The rotary hybrid vent does not automatically activate mechanical mode at low

wind speeds. It can either be manually shifted into mechancial operation through simple

switch or else have mechancial operation activated through digitical control measure in

the power supply, such as a thermostat. Even in mechancial mode, the performance of

the ventilator can be impacted positively by wind speed and stack conditions such that

the vertical vane hybrid can be considered an entirely new class of ventilation device. In

general, for each product size, the flow rate in mechanical mode is 3 – 5 times faster

than the equivalent vertical vane wind driven ventilator.

The technology was awarded the prestigious AIRAH (Australian Institute for

Refrigeration and Air Handling) award for Innovation Excellence in 2011.

The postive features of the vertical vane hybrid include

• The capability to operate in natural wind mode alone or mechanical with

wind and stack support.

• Best specific performance (cfm/W) ever recorded for a commercially

available mechanical device (∆p=0)

• Virtually inaudible operation in wind or mechanical modes.

• Unhindered performance in natural mode compared to equivalent

unpowered product (i.e. no reduction in Cd caused by presence of motor).

• No use of fan blades which reduce energy efficiency and create noise.

• The use of single phase German electronic commutating motor technology.

• 0-10v control (or 4-20mA ) available for the 900mm size product.

• The capacity to remove far greater heat loads than the equivalent size wind

turbine (e.g. 400mm hybrid removes five times the heat of equivalent size

400mm rotary wind vent at 30⁰C).

• The option to use any digital measure, such as CO2, VOC, NO, temperature,

humidity, wind speed, to activate mechanical mode.

• 200-277V AC 50/60Hz supply..

• Light weight (constructed primarily from marine grade equivalent aluminium).

• The ability to handle pressure losses typical of most tight louvres.

• Revolution rates of around 180/min (900mm size) – about 400/min (400mm

size) compared with less than 70/min for typical wind powered ventilators at

average wind speeds.

15

On the negative side, the vertical vane hybrid does not purport to be able to

manage medium to large pressure losses. In general performance will start to seriously decline over 20 - 25Pa loss although the higher revving 400mm size can manage at pressure losses approaching 60Pa. This behaviour obviously limits applications and the use of the vertical vane hybrid on lengthy ducting systems is not advisable. However, it does raise the challenge for consulting engineers to accurately assess pressure drops for projects and not just take conservative approaches which may limit the use of this energy saving technology.

The vertical vane hybrid, which can operate in passive mode only, or in mechanical

mode at world’s best energy efficiency, can be a valuable contributor towards LEED

points when used either alone or as part of a total air quality system. It is consistent with

the major objectives of LEED, namely:

To have a positive impact on the health of building occupants (by facilitating the

inflow of clean, fresh air).

To save money (product has zero operating cost in natural mode and an energy

efficiency in mechancial mode far lower than comparable size mechancial fans).

To promote renewal, clean energy (hybrid can operate in natiural mode and even

in mechancial mode efficiency is world’s best and can be reduced further by

above average wind speeds).

9. Applications of Vertical Vane Hybrid Technology.

The vertical vane hybrid ventilator has been sold globally now for 10 years. The

range of successful applications has been extensive and in some cases exceeded

theoretical expectations. Where performances, either energy efficiency measures or

flow capacities exceeded expectation for the application, the improvements have been

attributed to the unique properties of this new class of ventilation device – the capacity

to harness wind suction and stack effect while operating in mechanical mode. Some of

the applications, which have all been driven by the desire to reduce fossil fuel usage

and to introduce an element of sustainability, include the following:

9.1 Cooling of Electronics.

In Germany, Ventfair GmbH has developed a system referred to as GACS for

minimising the use of air conditioning to maintain the temperature of electronics in

wireless transmission stations under 35⁰C. The system applies negative pressure to

draw in filtered air at suitable rates and temperature, and at suitable times, to help

remove heat emanating from electronic modules. A 4 kW air conditioning unit remains

on standby for cases where external conditions are unsuitable. The vertical vane hybrid

400mm product is used as the driving force for this ‘free air cooling’ scheme and it is

controlled so that it first operates in passive mode but then escalates to mechanical

mode if conditions worsen. Dampers are installed in the ventilator for situations where

the air conditioning system must be activated.

16

Over 200 such installations have been carried out in Germany for the telecom

operator, EPlus. In Australia, vertical vane hybrid has been used for reducing heat load

inside train signal huts so that electronics can continue to operate effectively.

Fig 18. Vertical vane hybrid operating in mechanical mode for a roof top wireless station in Germany.

9.2 Removal of Heat from Power Transformers and Compressors.

All devices that use electricity give off waste heat as a by-product of their operation.

Transformers are no exception. Heat is generated in a transformer due to both the

resistance of the windings (load loss) and to magnetic effects primarily attributable to

the core (termed iron loss). A transformer with an 80⁰C temperature rise uses 13-21%

less operating energy than a 150⁰C rise unit. However temperature rise results from not

only how much heat is generated but also how much heat is removed. A lower-

temperature-rise transformer also has a longer life expectancy and importantly an

increased capacity. While rotary wind ventilators have been used to help dissipate heat

from power transformers they can be ineffective on very hot and low wind days.

Mechanical fans have proved expensive to operate and often noisy for near neighbours.

Vertical vane hybrid can provide natural ventilation when conditions are appropriate but

offers greater heat removal capacity in mechanical mode when conditions demand.

Vertical vane hybrid has been selected for removal of heat produced by

compressors in Australia’s huge National Broadband rollout.

17

Fig.19 Hybrid 900mm installation for National Broadband rollout.

9.3 Improving Air Quality and Comfort for places of community assembly.

Hybrid vent has been used to help improve air quality and improve thermal comfort

on places of worship, community and school assembly halls and town halls. The

hybrids are used in natural mode during cooler months to maintain acceptable air

quality but often revert to mechanical mode during the hotter, summer months when the

facility is occupied. Energy is conserved compared to the alternative of using air

conditioning.

9.4 Removing Heat and Odours from Gymnasiums and Sports Halls.

Gymnasiums and sports hall are other areas where demand ventilation is often

required when physically demanding sports are undertaken in warmer conditions. The

vertical vane hybrid can be activated into mechanical mode to meet this peak then

returned to natural mode when activities have ceased.

9.5 Removing Heat Load and Improving Air Quality in Factories and Warehouses.

Vertical vane hybrid has been used to either replace energy inefficient mechanical

fans or reduce demand for mechanical fans in many projects involving factories and

warehouses throughout the world including Tata Motors, India; Caterpillar, Singapore;

Tadim, Turkey; Coca Cola, Fiji; Amcor Can Beveridges, Australia; and Sahara Produce,

Indonesia.

9.6 Replacing Axial Fan Usage on Ventilation Shafts.

The application of hybrid vent for replacement of axial fans on ventilation shafts in

multi-storey buildings has been a surprising success. Pressure loss was always a major

concern yet projects undertaken on apartment buildings in Honolulu and in Sydney on

hotels have, from all reports, proved successful in terms of reduced energy costs,

lowering the impact of operating noise on top floor rooms while not compromising the

standard of room ventilation.

18

Fig. 20 Hybrid 600mm installed on ventilation shaft at 17 storey complex,

The Park at Pearl Ridge, Honolulu.

9.7 Augmenting Air Flow from Natural Ventilation shafts.

In parts of Europe and the United States, vertical vane hybrid has been used to

augment flow from ventilation chimneys servicing extended whole building ventilation

systems. At Washington State University School of Bio-molecular Engineering, the

building project incorporating the 900mm hybrid was awarded LEED gold standard. The

Building Automation System (BAS) measures the flow and direction of each solar chimney

with thermal dispersion sensors. When the natural buoyancy effect and wind drive flows

from the hybrid 900mm are insufficient, the BAS modulates the speed of the hybrid motors

to maintain target flow rate. Indoor and outdoor space temperatures are constantly

recorded and are part of the control algorithm. The system also provides for night cooling

of the building based on previous day’s high temperature. User operable windows in the

building space supplemented by automatically controlled windows higher in internal walls

ensure adequate fresh air intake to match supply needs and ensure target ACH rates are

achieved to maintain a healthy environment.

19

Fig. 21 Vertical vane hybrid 900mm used on School of Bio Molecular

Engineering, Washington State University.

9.8 Ventilation of School and College Classrooms.

Vertical vane hybrid has been used as the principal ventilation device on over 200

schools, colleges and Universities in Australia, the United States and France. This has

facilitated the construction of sustainable building designs.

Fig. 21. Use of vertical vane hybrid 400mm for ventilation of school

classrooms (project, Sydney, Australia)

20

10. Conclusion.

Passive ventilation systems have long been used to improve air quality and comfort

of buildings but in modern design lack performance certainty. This has led to various

forms of hybrid ventilating systems.

The development by CSR Edmonds of a hybrid ventilator class that combines the

capability for standalone natural operation, using stack and suction effects, and very

high energy efficient E.C. motorisation, without any dilution of natural flow rate

capability, is a world first innovative step for hybrid technologies. It provides a

technology that can harness the full potential of prevailing environmental conditions but

when required shift to mechanical operation, with extraordinary levels of energy

efficiency and inaudible operation, to ensure desired outcomes.

This new hybrid technology, termed ‘vertical vane hybrid’, has already been used

globally to reduce energy usage in many applications including the cooling of

electronics and transformers, replacement of axial fans on factories and ventilation

shafts, ventilating community halls, places of worship, school classrooms, and

gymnasiums, and more recently the integral component of a total home environmental

system [7].

Future developments and applications of vertical vane hybrid technology are

expected to be tied into the design of supporting systems of electronics and wireless

control and advances in motor design and capability.

References.

[1] S. J. Savonius et al, The Winged Rotor in Theory and Practice, Helingfors, Finland,

1925.

[2] AS/NZS 4740:2000 Natural Ventilators – classification and performance.

[3] N. Khan, Y. Su, S.B. Riffat, , A review on wind driven ventilation techniques, Energy

and Buildings 40 (2008) 1586-1604.

[4] A. Revel. Testing of two wind driven ventilators, Project no. E98/42/041, Sept. 1998.

. A report on behalf of Insearch Limited.

[5] P. Heiselberg, Natural ventilation design, The International Journal of Ventilation, 2

(4) 2004, 295-312.

[6] CSR Building Products Ltd, EP1794507, Hybrid Ventilator, Granted 1.05.2013.