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.
Good indoor air quality safeguards the
health of building occupants and
“if you want your workers to perform,
contributes to their comfort, wellbeing and
you have to let them breathe fresh air.”
work performance. Poor indoor air quality
in the workplace leads to discomfort, ill
Summary health, absenteeism and lower
Building owners and tenants can productivity. Green air is not necessarily
clean air and the drive for energy
benefit from breathing clean,
efficiency without sufficient regard for
pollutant free indoor air. High
building occupants can have significant
efficiency botanical air filtration, adverse economic consequences.
complementing the HVAC system, High efficiency botanical air filtration,
directly in the workplace, reduces directly in the workplace, reduces the
need for high ventilation rates, and
the need for high ventilation rates,
delivers tangible benefits of high quality
delivering high quality indoor air,
indoor air, complementing the HVAC
with energy savings in HVAC system and allowing for energy savings in
operations by lower ventilation HVAC operations by lower ventilation
rates in existing buildings and rates in existing buildings and reduces the
need to over-size HVAC systems in newly
reducing the need to over-size
designed buildings, and up to 20% saving
HVAC systems in newly designed
in energy use.
buildings. Up to 20% saving in
energy use, improved work Gains of 6 – 26% increase have been
performance of 6 – 26% increase, shown in improved work performance,
and lower ventilation costs can be
and lower ventilation costs of 3 -
conservatively estimated in the order of 3
5%, with a payback period of 12 –
- 5%. A payback period of
18 months. 12 – 18 months on a typical installation is
easily achievable.
Better Air Filtration

www.plantscleanair.com iplant@plantscleanair.com


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
Breakdown of a typical office

building operating cost structure:

 Salaries are over 80%

of business costs

 Rent is around 15%

www.plantscleanair.com  Remaining costs ~ 5%
iplant@plantscleanair.com


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.

Example

2
Two biofilter walls each 2.4m wide x 1.7m high totaling ~ 8 m are installed to filter

2
the air in an open plan workspace of NLA 450 m at a cost of $20,000 ($2500 per
2
m)

2
(At a workplace density of 10m /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.



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
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.



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)



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.
Direct source control with air cleansing is the only method to capture contaminants at or near the


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