1 Hybrid Ventilation – Innovative Use of Renewable Wind Energy Allan Ramsay CSR Edmonds ( a business unit of CSR Building Products Ltd, Sydney, Australia). Email – [email protected]---------------------------------------------------------------------------------------------------------------- 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.
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Hybrid Ventilation – Innovative Use of Renewable Wind Energy
Allan Ramsay
CSR Edmonds ( a business unit of CSR Building Products Ltd,
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.
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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.
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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.
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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.
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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.
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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)
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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.