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Transcript of Ipt energy iaq 2012
Innovative Plant Technology Botanical air filtration 2013
Saving energy through better air filtration for
healthy indoor environments
Ronald Wood PhD BSc.
Innovative Plant Technology Pty Ltd.
“if you want your workers to perform,
you have to let them breathe fresh air.”
Summary
Building owners and tenants can
benefit from breathing clean,
pollutant free indoor air. High
efficiency botanical air filtration,
complementing the HVAC system,
directly in the workplace, reduces
the need for high ventilation rates,
delivering high quality indoor air,
with energy savings in HVAC
operations by lower ventilation
rates in existing buildings and
reducing the need to over-size
HVAC systems in newly designed
buildings. Up to 20% saving in
energy use, improved work
performance of 6 – 26% increase,
and lower ventilation costs of 3 -
5%, with a payback period of 12 –
18 months.
Better Air Filtration
Good indoor air quality safeguards the
health of building occupants and
contributes to their comfort, wellbeing and
work performance. Poor indoor air quality
in the workplace leads to discomfort, ill
health, absenteeism and lower
productivity. Green air is not necessarily
clean air and the drive for energy
efficiency without sufficient regard for
building occupants can have significant
adverse economic consequences.
High efficiency botanical air filtration,
directly in the workplace, reduces the
need for high ventilation rates, and
delivers tangible benefits of high quality
indoor air, complementing the HVAC
system and allowing for energy savings in
HVAC operations by lower ventilation
rates in existing buildings and reduces the
need to over-size HVAC systems in newly
designed buildings, and up to 20% saving
in energy use.
Gains of 6 – 26% increase have been
shown in improved work performance,
and lower ventilation costs can be
conservatively estimated in the order of 3
- 5%. A payback period of
12 – 18 months on a typical installation is
easily achievable.
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Innovative Plant Technology Botanical air filtration 2013
For several decades, indoor air researchers have seen an association between an inadequate
supply of outdoor air and discomfort and illness among building occupants. Poor indoor air
quality in the workplace leads to absenteeism and lower productivity. Good indoor air quality
safeguards the health of the building occupants and contributes to their comfort and wellbeing.
Perceived air quality (PAQ) is the basis for current ASHRAE guidelines and standards for
ventilation. Occupant evaluation is subjective and not indicative of health risks associated with
breathing polluted air, and confusies air movement with air freshness (Melikov and Kaczmarczyk
2012).
The conventional approach to improve indoor air quality is to increase the ventilation rate to
dilute pollutants in the workspace, however the additional airflow from the various ventilation
modes substantially increases building operating costs, consuming as much as 30% of the total
energy use, with little appreciable improvement in air quality.
Some green buildings claim a designed 50% increase in ventilation rate above BCA code
requirements gives better air quality, “From an energy and climate change perspective, we want
to reduce ventilation rates.” (Fisk et al. 2012). There is considerable mechanical system design
over-sizing with the gap between operational loads and design loads leading to a 20% increase
in air conditioning system energy use (Younes and Carter, 2006)
Economics of high quality indoor air
Local filtration in the workplace reduces unwanted gaseous pollutant and particle re-circulation
with potential improvement in productivity from breathing cleaner air, while providing protection
for the HVAC components.
Botanical air filtration is able to supply clean, filtered air equivalent to 80% of the required
outdoor air supply for an office space, resulting in reduced energy costs from lower ventilation
rates, reduced maintenance/replacement of fans and filters (Zhang 2010).
Cost perspective
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Breakdown of a typical office
building operating cost
structure:
Salaries are over
80% of business
costs
Rent is around 15%
Remaining costs ~
5% energy, water
and maintenance
Innovative Plant Technology Botanical air filtration 2013
As salaries (plus on-costs) are the major office building expense, even small improvements in
indoor air quality can have a major effect on operating costs and efficiencies. Productive
employees accomplish more output and more output (or fewer employees) means better value
and lower costs. Increased worker performance brings a distinct economic advantage. For
example, the savings from a modest 1% increase in performance could be sufficient to offset a
50% increase in energy costs in many buildings (Lawrence Berkeley National Laboratory 2012).
However, with botanical air filtration, a decrease in energy costs of 3 – 5% can be achieved as
well as a 1% increase in performance.
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Example
Two biofilter walls each 2.4m wide x 1.7m high totaling ~ 8 m2 are
installed to filter the air in an open plan workspace of NLA 450 m2 at a
cost of $20,000 ($2500 per m2)
(At a workplace density of 10m2/person (AS 1668.2) this provides clean
filtered air for up to 45 occupants).
Simple Payback Period
Payback Period (years) = $ Capital investment
$ Annual Savings
Assuming an occupancy rate of only 20 persons, and a 1% improvement
in performance, as a straight-line approximation, at an average salary
cost of $72,000 (Australian Bureau of Statistics, May 2012), this becomes
$720 per person, a total of $14,400
Payback Period (1.4 years) = $ 20,000
$14,400
Similarly at a full occupancy rate of 45 persons the payback period would
be around 6 months.
There are additional energy savings from reduced ventilation rates, lower
filter pressure drop, and less maintenance and replacement costs of HVAC
fans, filters and pumps and by avoiding design over-sizing.
Biofilter maintenance costs equate to $6.70/m2floor space/p.a. or
approximately $150 per person per annum at an occupancy rate of 20
persons, or $67 for 45 persons.
Clearly minimal costs compared to potential savings.
Innovative Plant Technology Botanical air filtration 2013
What are we actually breathing?
Ventilation “fresh air” is generally contaminated, mainly with motor vehicle emissions that
combine with a multitude of indoor contaminants from building materials, various operational
activities, and building occupants, to form a “cocktail” of air pollutants.
Building codes mandate that new (and green retrofit) buildings be designed for ventilation rates
appropriate for maximum occupancy, a condition that almost never exists. A building whose
ventilation rate is code compliant is already over-ventilated the vast majority of the time, (Younes
and Carter 2006), so providing ventilation over and above code requirements may provide little
or no health benefit while substantially increasing energy consumption.
There are no regulations in Australia on chemical emissions from building materials. De facto
environmental certification schemes have been developed by industry associations that include
material emission limits, but the legal standing of these certifications raise considerable doubts.
Many studies are now demonstrating adverse health effects at levels of air pollutants well below
published air quality guidelines. Neither indoor nor outdoor environmental sampling is a good
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Innovative Plant Technology Botanical air filtration 2013
predictor of personal exposure, nor energy rating systems an indicator of clean, uncontaminated
indoor air.
Example No-VOC paints
According to the U.S EPA “no-VOC” latex paint does not necessarily mean no emissions. Tints
contain high VOC levels and linseed oil used as a drying agent in “low VOC paints” reacts with
ozone, nitrogen oxides or hydroxides (usually from outside supply air) to form oxidation products
that are potentially irritating or harmful to health.
Carbon dioxide levels impair decision-making performance
Carbon dioxide levels are often used as a surrogate for occupancy levels and for determining
ventilation rates. Recent findings from the U S Department of Energy’s Lawrence Berkeley
National Laboratory (2012) show that even code compliant carbon dioxide levels (700 – 1000
parts per million (ppm), typical of the lower levels in many offices, have significant adverse
effects on decision – making performance. Carbon dioxide levels up to 5000 parts per million
have been measured in some offices, particularly in the afternoon and with high occupancy
rates. The most dramatic declines in performance were for “taking initiative and thinking
strategically.”
High quality botanical air filtration reduces carbon dioxide and increases oxygen levels while
making it possible to reduce ventilation rates, reduce energy costs and improve the work
environment with cleaner, pollutant free air.
Air filtration
Air filtration is a critical component of a building’s energy performance, so
HVAC filters should be considered as energy using products. The key issue in filter energy
efficiency is the filter’s pressure drop.
The conventional approach to improve indoor air quality is to increase the ventilation rate to
dilute pollutants in the workspace, however the additional airflow from the various ventilation
modes substantially increases building operating costs, consuming as much as 30% of the total
energy use, with little appreciable improvement in air quality. Increasing outdoor air quantities in
mechanical ventilation systems will usually lead to increased coil sizes, and possibly increased
chilling and heating plant capacity. New filters can be a source of pollutants after three months of
operation, yet the average filter lifetime can be 6 months to 12 months and are generally not
changed until the pressure drop reaches the recommended replacement value. Consequently
increasing the outdoor airflow rate reduces the benefits of cleaner air that should result.
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Innovative Plant Technology Botanical air filtration 2013
Schematic make up of an indoor air biofilter Image courtesy of Nedlaw Living Walls Inc
Engineering solutions - Existing buildings
Existing buildings that have the greatest difficulty in raising outdoor airflow rates to meet current
standards were built with energy efficiency in mind and may have the least excess capacity.
Conventional indoor air pollution control
The Building Code of Australia (BCA) has mandated ventilation rates appropriate for maximum
occupancy. Occupancy rates can vary depending on workspace design and use. Conventional
Variable Air Volume (VAV), Constant Air Volume (CAV) and Fan Coil Units (FCU) systems all
employ the ‘perfect mixing’ principle. This will unavoidably mix all the pollutants in the indoor
space before they are re-circulated for exhaustion or re-conditioning. The displacement system
(DS) has the advantage of limiting the diffusion of the pollutants.
One major problem of conventional design is the lack of a method to control the path of the
contaminant air. For general ventilation it consists of dilution and removal of contaminants;
airflow patterns within rooms; airflow direction within the space and negative pressure in rooms.
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Innovative Plant Technology Botanical air filtration 2013
Direct source control with air cleansing is the only method to capture contaminants at or near the
source.
Various engineering solutions are employed to control and reduce operating costs. Managing the
hours of operation of the ventilation system, e g, switched off overnight, airflow reduced to 10%
overnight or continuous 100% operation.
Turning off the ventilation system or reducing the airflow outside working hours significantly
increases the pollutants emitted by the filter immediately the system is turned on, and has been
shown to persist for up to two hours.
High quality filtration – health effects
Providing high quality filtration in the workspace, not only delivers substantial energy and cost
savings, but also has a measureable effect on building occupant health and wellbeing and
improvement in performance. Although HEPA filters provide high filtration efficiency, they are
not necessarily appropriate for all HVAC applications. Existing HVAC systems cannot usually be
upgraded to HEPA filters without a complete retrofit of the air handling system, due to the high
pressure drop and potential leakage associated with them. As they remove only particulates they
require activated carbon filters to remove gaseous pollutants (VOCs) that are generally not
recyclable and become a source of toxic waste.
Pressure drop
The pressure drop across the mechanical filters in a typical HVAC system in a standard
office building increases fan energy use, adversely affecting air-conditioning system
performance and efficiency (Nassif 2012). It is generally designed to be less than or
equal to 124Pa. but the pressure drop across a HEPA filter can range from 250 –
500Pa. Local filtration reduces unwanted gaseous pollutant and particle re-circulation,
with typical system pressure drops of less than 75Pa, mainly from the diffusers There is
a clear need for a low-pressure drop filter that removes hazardous or harmful
contaminants, effectively.
Botanical air filtration
To provide clean, pollutant free air to building occupants, direct source control with air filtering is
the only method to capture contaminants at or near the source. This complies with Australian
Standard AS 1668- 1.2. The use of ventilation and air conditioning in buildings Part 2 Appendix
D (D) allows, “cleaning recirculated air to provide an equivalent dilution effect (i.e.) equivalent
outdoor air. (Draft AS 1668-1.2 2012)
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Innovative Plant Technology Botanical air filtration 2013
Indoor air biofilters can provide clean indoor
air directly to an adjacent space or distribute it throughout the building’s HVAC system. Image
courtesy of Nedlaw Living Walls Inc.
The botanical air filter is a dynamic system, actively improving indoor air quality directly in the
workspace. A vertical hydroponic green wall (soil free) is designed as a living, self regenerating
air filter, removing indoor contaminants such as dust, volatile organic compounds (VOCs),
bacteria and viruses, allowing clean fresh air to be distributed throughout the space by the
mechanical ventilation system.
Operating 24/7 strategically located, biofilter walls can present an environmentally positive
corporate image, while making a real difference in "breathable" air quality. Biofiltration of the air
circulating within the building envelope enables clean, cool air to be delivered, reducing the need
for 20-30% outside air to be conditioned, saving commensurate energy costs. It contributes to
thermal comfort by on average, a 0.5oC temperature decrease and 15.0% RH increase.
Biofilter energy requirements
Power consumption is only required for a small water recirculation pump, and a plenum
extraction fan. The power consumption for the water pump is 2 kWh/m2 floor area and the
plenum fan 0.2 kWh/m2 floor area for a total 2.2kWh/m2 floor area.
The energy consumed by the water recirculation pump and the fan drawing air into the biowall
plenum is small. Automated controls can allow the fan to operate only during occupied hours,
however the water recirculation pump needs to operate continuously.
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Innovative Plant Technology Botanical air filtration 2013
Energy use comparison office light and powerkWh/m2
Innovative Plant Technologywww.plantscleanair.com
NABERS iplant™
For comparison, the Property Council of Australia’s best-practice existing office building tenant
light and power consumption is 62.5kWh/m2 for a building in operation 10 hours a day, 250 days
a year.
The NABERS (ABGR) 5 Star benchmark for office tenants is equivalent to 52kWh/m2. Clearly,
the energy consumption associated with a biowall is relatively minor, and represents minimal
ongoing energy costs.
The Umow Lai Living Wall Biofilters are strong evidence of effective, low technology gas phase and particulate filtration providing air cleaning directly in the workspace, leading to better indoorenvironmental quality (IEQ) and the resultant benefits to occupants
Self-regenerating air filter solution
Botanical air filtration gives the option of minimum code-compliant fresh air rates while delivering
high quality fresh air to building occupants at low cost, with a less than 2 year payback, either
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Innovative Plant Technology Botanical air filtration 2013
incorporated into the building’s air handling system or as a free standing unit, ranging from room
size to multi-storey.
The technology can have a substantial impact on the energy balance and air quality of the
space, as well as reducing ventilation costs, and “lower capital costs due to smaller mechanical
and electrical infrastructure” (Younes and Carter 2006), while requiring a very small footprint.
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CASE STUDY
Umow Lai - Consulting Engineers, Melbourne, Bio-filtration Walls
In an Australian first, five bio-filtration walls, designed by Umow Lai in
conjunction with Innovative Plant Technology were installed throughout
the office. The biofiltration walls act as natural biological filters, removing
Volatile Organic Compounds (VOCs) from the air, resulting in a healthier
working environment.
Independent testing of Total Volatile Organic Compounds (VOCs),
airborne microbes and surface microbes on biowall ducts was conducted
after two years of continuous operation.
- low levels of VOCs (at or below detection limits)
- very low microbial count
- higher levels of fresh air
- overall 13% improvement in productivity
University of Guelph Humber, Canada 2004
A 4 storey biofilter wall 10m wide by 16m high
totallling160m2 and fully integrated into the building air
handling system, capable of delivering 18,000L/sec clean
air.
Clean Air Delivery Rate (CADR) Average 40L / m-
2biofilter S-1
Filters drawing around 0.1 m S-1 generating between
80 to 100L S-1
i.e. 2,880,000 L per 8 hours, demonstrating a
capacity to provide a large volume of clean air to
the student population.
As a comparison, we breathe 6 -10 L of air per
minute and the biofilter delivers 100L/S-1 that is
Innovative Plant Technology Botanical Air Filtration 2012
References
Australian Standards revised. Draft AS 1668-1.2 The use of ventilation and air conditioning in buildings Part 2. HVAC&R Nation November 2011.
Fisk WJ., et al. Changing ventilation rates in U.S. offices: Implications for health, work performance, energy, and associated economics. Building and Environment 47 (2012) 368-372
Lawrence Berkeley National Laboratory “Elevated Indoor Carbon Dioxide impairs Decision-Making Performance” Berkeley Lab News Center, October 17, 2012
Melikov AK. and Kaczmarczyk J., Air movement and perceived air quality. Building and Environment 47 (2012) 400-409.
Nassif Nabil., “The impact of air filter pressure drop on the performance of typical air-conditioning systems” Build Simul (2012) 5: 345-350
Younes A., Carter G., “Internal heat load allowance- is more actually better” Ecolibrium October 2006.
Zhang J., Botanical Air Filtration ASHRAE Journal 138-140 December 2010.
US EPA (2000) Energy Cost and IAQ Performance of Ventilation Systems and Controls
Next Steps
To discuss how iplant Living Wall Biofilter® systems can enhance your buildings and bring value to your tenants and clients, contact Dr. Ronald Wood at Innovative Plant Technology e-mail [email protected] or telephone (02) 9654 1264.
www.plantscleanair.com +612 9654 1264