Indoor air quality (IAQ) is generally under acknowledged in favor of indoor environmental quality (IEQ). Building rating schemes pay lip service to IAQ while promoting IEQ as the main requirement for building occupant health and comfort. Only high quality air filtration can ensure clean "breathable" air.

1. Building Services
FEATURE
Air we breathe taken for granted
by Patrick Durrant
T
he president of the American Society of Heating,
near the source. AS 1668 – 1.2.2012 “The use of ventilation
Refrigerating and Air-conditioning Engineers
and air-conditioning in buildings” Part 2 Appendix D,
(ASHRAE), William Bahnfleth, sees “a critical shift
allows “cleaning recirculated air to provide equivalent
in thinking from a goal of indoor environments that are
dilution effect”, ie equivalent outdoor air, but this still
‘acceptable’ to occupants, to a fundamental obligation to
delivers less than optimum indoor air quality.
provide indoor environments that are truly healthy and
The three critical components of indoor air quality
productive, while conserving resources”.
(IAQ) management are: source control, dilution and air
Compliance with building ratings schemes generally
cleaning.
means that the air breathed by the majority of building
Source control
occupants is of an “acceptable” standard; however, this
Low VOC construction materials are important; however,
less than optimum air quality has a significant effect on
there are no regulations of chemical emissions from
performance and long-term health. Outdoor air is the only
commonly used building materials. Some industry
source of ventilation supply air. This “fresh air” is generally
associations have developed environmental certification
contaminated with motor vehicle emissions, including
schemes but their legal standing is in doubt.
diesel particulates from trucks and buses. Building
Dilution
filtration systems are generally designed to remove the
Wood says the conventional approach to diluting the
larger particulates but not the gases, and so our lungs
toxicity of the air by increasing ventilation rates is only
become the final filter.
treating the symptoms, not the cause, and it substantially
Dr Ronald Wood, director of Innovative Plant
increases capital, operation and maintenance costs.
Technology, stresses that the non negotiable goal for
In addition, this approach results in little appreciable
sustainable buildings must be to provide healthy, pollution
improvement in “breathable” air quality, as some indoor
free air to building occupants. The drive for energy
chemical reactions occur faster than the ventilation rate.
efficiency without sufficient regard for
building occupants can have significant
adverse economic consequences for both
building owner and tenant.
Although it looks like a green wall,
active botanical air filtration is a high
efficiency system with no leaks, no
bypass and no filter changes. Its closed
loop system is self-regulating, selfrepairing, with no toxic residues and
operates 24/7 in the dark as well as the
light. Contaminated air is drawn through
the planted wall, transferred from the
gas phase to the plant root biofilm
and metabolised by the associated
micro-organisms before returning as
clean, uncontaminated air back to the
breathing zone. It has excess capacity to
supply clean, unpolluted 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
and replacement of fans and filters.
According to Wood, direct source
control with air filtering is the only
method to capture contaminants at or
A living green wall in Umow Lai’s Melbourne office.
Photo: Ronald Wood
Engineers Australia | December 2013
57

2. FEATURE
Building Services
Air cleaning
Most building filtration systems don’t remove gaseous
pollutants or ultrafine particles and upgrading existing
HVAC systems to HEPA (high efficiency particulate
air) filtration usually requires a complete refit of the air
handling system due to potential leakage from mismatch
of filter frames and increased energy consumption from
the higher pressure drop (250Pa). Complementing the
HVAC filter system, active botanical air filtration reduces
unwanted gaseous pollutant and particle re-circulation.
This results in typical system pressure drops of less than
75Pa with the reduction in high ventilation rates leading to
a potential 20% energy saving.
Biofiltration of the air circulating within the building
envelope provides unpolluted, clean, cool air, reducing
the need for 20-30% outside air to be conditioned. This
provides savings on energy costs and contributes to
thermal comfort by, on average, a 0.5°C temperature
decrease: an effective way of achieving ASHRAE’s goal
of a healthy and productive indoor environment while
conserving resources.
System security unclassified
Governance of Security Systems
by William MacCallum
Book review by Patrick Durrant
W
illiam MacCallum is an engineer, technical
writer and security manager with many years
experience working mainly in defence, and has
been instrumental in developing Australian Department of
CAPTION IMAGE TO COME
Defence computer security policy. While most of his work
has resulted in many classified manuals and documents,
he perceived a need for an unclassified document that
would cover all aspects of system security. As such,
Governance of Security Systems is a handbook for designing
and implementing a security program that will protect
businesses.
Aimed at security managers with the responsibility
for drafting policy, standards and procedures, the book
provides a broad introduction to the governance of
security systems and the development of a supporting
security program. Split into two parts, the first deals with
security structure and policy, and introduces the three
core elements: infrastructure, information and personnel
as well as security intelligence. The second part deals with
operational security – the implementation of policy and
standards in an operational environment.
The book is neatly structured and makes for easy
reading. At the end of the book there are useful tips
on education for security personnel and how a security
system should be maintained once established. A detailed
glossary will help those who are unfamiliar with some of
the terminology.
A must read for system security managers, Governance
of Security Systems would also serve as a useful
background for chief executive officers and associated
executive directors who need to understand the principles
of system security and their application in the public and
private sectors.
EA TEchnicAl GuidElinEs/prAcTicE noTEs
Engineers Australia has a number of technical guidelines/practice notes to assist members in the practice of their profession. They include:
u
u
Practice Note for Design Fires (2012), published by the Fire Safety Society (a Technical Society of Engineers Australia)
Practice Note for Fire and Life Safety in Existing Buildings During Construction (2012), published by the Fire Safety
Society (a Technical Society of Engineers Australia)
The guidelines can be accessed through EA Books, a department of Engineers Media,
a wholly owned subsidiary of Engineers Australia.
Go to www.eabooks.com.au and click on Guidelines/Notes.
58 Engineers Australia | December 2013