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.

www.plantscleanair.com [email protected]


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%

Remaining costs ~

5% energy, water

and maintenance


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

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.


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.



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

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)



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.



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



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.


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

http://www.plantscleanair.com/

mailto:[email protected]

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Ipt energy iaq 2012