LIFTING THE LID
Thinking
Ian Walker, PROTECTIVE
COATINGS SBU DIRECTOR
FOR AKZONOBEL, CONSIDERS
HOW MATERIAL SELECTION
IMPACTS ON THE WHOLE LIFE
CYCLE OF TALL BUILDINGS
Xiaoshan International Airport
T
he urban landscape around us is
continually changing. Across the
world there is increasing demand for
complex, tall building designs which
in essence look to maximise building potential
for a given footprint.
Tall building design has seen an increased
demand for innovative solutions, which has led
to unique architectural and structural solutions
with inspiring results. The construction industry
is being increasingly pushed to develop new
technologies that complement modern day
designs.
Coatings technology is an example of an
integrated approach which is increasingly
being used as a design medium, for example
structurally-engineered fire protection, to arrive
at optimised, economic and safe steelwork
designs. Even though ‘paint’ could be regarded
as ubiquitous, the fact is that the use of paint and
coatings opens up opportunities for the use of
new materials and new construction techniques.
Developments have been based on tall
building design pushing the boundaries of
construction, including areas of durability, fire
protection, finish aesthetics, functionality and
sustainability.
New construction, together with historical and
heritage buildings, require suitable solutions to
extend their serviceable lifetime or to sensitively
restore them to their former glory. Extending
maintenance intervals is seen as a vital role in
all buildings, and appropriate solutions and can
ensure that modern day tall buildings become
the heritage of tomorrow.
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Historically, paint and coatings may have been
considered purely for decorative purposes, and
the choice of selection could be perceived as
simply “What colour do you want?”
Over the years however, as with all
manufacturers of materials used in construction,
listening to the requests of designers and
working alongside creative and innovative
people in the design chain has led to advanced
solutions to address specific issues.
Owners are looking for assurance that their
buildings will be cost effective, not only to
maintain but also in terms of improving rental
opportunities. In this context of coatings,
durability is essentially keeping the building
looking good for longer.
To illustrate the issue of durability, consider
curtain walls and windows. The performance
of these elements is important, not only from
a structural point of view, but also from a
durability perspective.
The advent of high performance paints for
aluminium curtain walls in the 1960s opened
up new design and performance options. The
impetus for the paint industry has been to
develop products that will stay looking good
for as long as possible. The coatings need to
be resistant to the effects of sunlight, heat and
moisture, which is normally assessed in terms
of improved colour retention and reduced
changes in gloss. Both these attributes maintain
the aesthetics, but also ensure long term
protection of the aluminium by reducing coating
degradation, which in turn can result in reduced
protection, leading to corrosion.
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LIFTING THE LID
LIFTING THE LID
The paint and coatings industry has both
driven and been driven by key independent
architectural paint standards including the
American Architectural Manufacturers’
Association AAMA 2605, 2604 and 2605
and the European Qualicoat and GSB quality
labels. These standards have raised their
performance requirements in terms of gloss
retention (amongst other things), and both
liquid and powder coatings have kept up with
this. In fact, the coatings industry lead the way
by developing new products, and the industry
standards raised their performance expectations
based upon these new materials.
DURABILITY
One of the key challenges with any material
used in construction is the time it takes until it
first requires maintenance, or rather how long
will it be before remedial, repair work or indeed
replacement has to be carried out.
Importantly, evidence of these high levels
of performance are all around us on buildings
which have been successfully coated with
advanced products, and now boast many years
of real life ‘track record’.
Extremely durable coatings are not just
limited to the external facades. Tougher wall
paints for plaster and masonry now look better
for longer, have lower maintenance costs and
reduce disruption from trades working in an
occupied building.
As buildings grow taller, a greater number of
people pass through them, so public spaces can
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be kept in better condition with this increased
demand on their aesthetic durability.
Some paints, particularly those designed for
use on structural steel, could be regarded as less
interesting in terms of evolution and potential for
improvement. However, with new developments
in technology, traditional ‘alkyds’ have been
superseded by paints with increasing levels of
durability. This has enabled the use of structural
steel as a design feature, by allowing the steel to
be exposed where it was once concealed.
FUNCTIONAL PROTECTION
Functional protection is all about coatings
that ‘do things’. Coatings can make a building
safer, either by protecting the fabric or actively
improving the environment for the occupants.
When it comes to the materials used in
construction, one of the most important
developments associated with the majority of
structures, and especially tall buildings, is that of
fire protection. The issue of life safety is critical
in buildings and nowhere more so than in tall
building design. By ensuring the stability of a
building in the event of a fire, preserving heritage
in terms of maintaining the structure, mitigating
against the consequence of total collapse with
respect to other potentially historic buildings in
the immediate vicinity, and more importantly,
helping to save the lives of the occupants.
Fire protection coatings have evolved from
their origins in space vehicle re-entry application
in the 1970s into everyday structural engineering
applications. Fire protection options such as
concrete, boards and cementitious coatings
have always been available to architects, but the
desire to have visually exposed steelwork was
always compromised using these methods.
Fire protection coatings used in buildings
today comprise of what we call thin film
coatings, which appear very much like typical
paint and can be used to express forms created
by the steel itself. More importantly however,
these coatings are designed to swell up in
the event of a fire (or intumesce) to form a
char layer that insulates and protects the
underlying steelwork. The steelwork industry has
embraced the use of intumescent coatings as a
construction material.
Around 20 years ago, these types of coatings
were not common and were considered
expensive in relation to other methods. However,
through increased commercial competition,
innovative development and the growth of fire
engineering, these materials are now common
in construction. In fact, evidence shows that the
majority of tall buildings in London today now
adopt intumescent coatings as their preferred
choice of protection.
Internally, coating manufacturers are
starting to incorporate their own structural fire
engineering divisions with qualified engineers.
These teams work very closely with structural
engineers, steelwork fabricators and contractors
across the world to arrive at optimised,
economic, safe and robust solutions. It is no
longer about a simple estimate of material
volume – in reality it is more of a consultancy
service. These are people who work with Building
Information Models or “BIM models”, write
software and integrate into project design teams
to assist in structural engineering calculations
and help to arrive at optimised designs.
In the context of tall buildings, optimisation
is now paramount. The construction chain
expects a one-coat or minimum-coat application
to ensure quick, efficient construction
and minimum trade times. In many cases,
manufacturers can now advise on modifications
to the steelwork design to optimise the fire
protection system.
We always listen to our clients and the
industry, and over the years we’ve seen many
developments. The events of the World Trade
Center collapse brought fire and structures to
people’s attention. When AkzoNobel worked on
the New York Times building, not only did we
have to contend with slender, exterior steelwork
in a salty and wet environment, together with
high fire resistance periods, we were also asked
to demonstrate resistance to blast and explosion.
This building was the first high-rise to be
completed after 9/11 and stands as a testament
to the heritage of New York, and will do so for
years to come.
But fire protection is not just about helping
to maintain stability of the steel structure.
Internal elements such as walls and ceiling tiles
are coated with materials that reduce ignition
risk and minimise the potential for spread of
flame. As a result, these coatings have been
developed to align with the needs of fire safety
strategies, specifically, to align with the needs of
tall building design in which egress of occupants
down protected stairs and through protected
corridors is critical.
Functional coatings can be used to provide
protection against other hazards in buildings. For
example, in areas where people live and work,
surfaces can be protected with anti-bacterial
paints. Obvious areas are washrooms and
kitchens, but anything that is regularly touched
by many people can be protected with coatings
that kill bacteria and reduce the risk of the
spread of infection. In areas where formaldehyde
emissions are a significant concern both during
and post construction, coatings are available that
actively convert formaldehyde into water vapour
which brings obvious health benefits to the
occupants of the building.
SUSTAINABILITY
Sustainability means many things to many people.
Manufacturers of construction products take their
sustainability responsibilities very seriously.
In the coating industry the term ‘sustainability’
can include a number of different criteria. We
work with designers to realise their potential
with respect to Green Building initiatives
including LEED and BREEAM certification.
This will typically take the form of
environmental, social and economic influences.
In the context of tall building design, the
sustainability impact can be significant, and
potentially none more so than in historic cities
where preservation and sensitivity can be
paramount.
There are some obvious areas that come to
mind when considering paints and coatings.
One particular example is the removal of lead
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LIFTING THE LID
The Media TIC building in Barcelona
© José Miguel Hernández
The Shard in London
as a pigment. Reducing solvent content, or
VOCs (Volatile Organic Compounds), has also
been a focus for the industry to make coatings
application a safer process.
Changing the way paint is manufactured
with respect to its raw materials and the way
it is applied can make significant contributions
to overall sustainability criteria of economics,
environment and the community. Examples
include coatings that require lower temperatures
to react and cure, saving both energy and
money. Coatings that are durable, require little
or no maintenance or need fewer coats, all
contribute to reducing the environmental impact.
There are internal decorative paints that
when applied to walls can reflect more light
within the room. This brings the dual benefit
of an improved working environment and the
opportunity to reduce the amount of artificial
lighting – saving both cost and energy.
Exterior coatings for either metal cladding or
masonry on walls and roofs can reflect sunlight.
Again there is the dual benefit of keeping a
building cooler and reducing the need for
expensive air conditioning. This is a factor for
reducing the urban heat island effect. In the
Shard, Renzo Piano gave the supporting façade
elements neutral white and grey colouring to
allow the reflection of the sky to provide the
main visual impact. Piano’s use of glass also
had a sustainability angle – firstly the use of a
double skin (a single glazed exterior and double
glazed interior skin, with blinds sandwiched
between), and secondly by allowing light to
penetrate deep into the floor areas, minimising
the need for artificial light.
These are features that are common in the
designs of many tall buildings as they open up
the façade and bring light into the floor space.
The fully glazed option provided by high-rise
developments has almost eliminated traditional
brick or concrete construction and replaced it
with lightweight aluminium frame solutions.
Any coating that lasts longer could contribute
to improving its sustainability score. Reduced
quantities of raw materials are required, less paint
has to be made and shipped, fewer journeys are
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made by applicators and less paint remains on the
substrate when it is eventually recycled.
Types of coatings have changed. The traditional
paint in a can is still the most widely used, but
different ways of making coatings such as powder
coatings have improved material utilisation. In this
instance, coatings are used in a dry form and less
material is wasted during application.
PRODUCTIVITY
When it comes to tall building design,
productivity and efficiency are vital. Essentially,
you want to be able to construct a building as
quickly and safely as possible, while ensuring
that things are done ‘right, first time’.
One simple fact about a coating is that it is only
as good as the application. As you might expect,
application in the rain on a rusty surface simply
doesn’t work. Also, spray applying paint onto
steelwork at the top of a skyscraper, exposed to
high winds is likely to result in huge wastage.
Many of the benefits that coatings can provide
rely on the correct selection of substrate, good
preparation and good application. This ties in
with modern building techniques, where more
components are prefabricated off site. This
can have enormous potential for tall buildings,
as painting of primers and fire protection for
example, can be done in a controlled factory
environment that will give better performance. In
this way, use of material can be better controlled
thereby improving costs. Steelwork is then
transported to site, and lifted into place; already
protected, to reduce additional trades on-site
and improve efficiency of construction.
The fast pace of high-rise development in
China is seeing the pre-fabricated option become
more popular, and it has also necessitated
off-site coating application. Modular building
is a good example of how off-site manufacture
can minimise timescales and costs associated
with the construction of tall buildings.
Curtain wall design in particular provides
another example of coatings applied in a factory
environment. Aluminium extrusions are carefully
cleaned and pre-treated before the coating is
sprayed in either liquid or powder form under
controlled conditions. Quality control relating to
coating thickness is managed closely to provide
the correct level of protection whilst minimising
material usage.
Perhaps the ultimate in off-site controlled
application is the process used to coat sheet metal
which is fabricated into cladding or panelling
systems. The coating is applied to continuous
metal rolls or coils of metal at high speed. Again
this brings the combined benefits of excellent
application and optimised material utilisation.
As is the case in all markets, the coatings
industry has not worked in isolation. Paint and
coatings manufacturers have had to be aware
of the developments in new materials and
construction techniques, such as the increasing
use of structural glazing. Coatings have to be
formulated which both adhere to the substrate
and ensure the adhesion of the structural
adhesives to the coating. Integrity of the coating
is required to resist the forces from the weight
of the glass that is in turn being supported by
the metal/ coating/adhesive combination.
THE IMPORTANCE OF COLOUR
Visual appearance is important, nowhere
more so than in cities with a strong sense of
heritage in which designs sympathetic to their
surroundings are key.
One of the first things that comes to mind
when paint and coatings are mentioned is
colour. Whether it is in the home, on a car, on
a plane or on a multi-storey building, colour is
visible and creates a lasting impression.
Colour can be a signal, it can promote a
brand and it can express an architect’s vision.
Colour and design can have an impact on
the external and internal design of a building.
This aspect of design can be carried all the
way through to fixtures and fittings; be they
radiators, furniture or lighting.
Coating solutions can really help to
emphasise and realise a designer’s intentions.
Paint technology has developed in many
ways to allow the use of more exciting
colours. Not only does paint come in standard
gloss and emulsion, but it has developed
to incorporate metallic colours, reflective
finishes, different shades, opaque coatings
and translucent coatings.
The result is that structural and nonstructural elements, that in the past were
either hidden or painted in standard
shades, are now central to the design by
being exposed.
Striking effects can be realised and, in
the context of tall building design, some
very innovative, creative and unique
designs are only possible because of
LIFTING THE LID
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the advances in coatings technology. Although
perhaps not a tall building by its nature, the
coloured columns in Madrid Barajas Airport
reflect this approach by creating a kilometre
long vista of graduated tones.
Coatings can make one material look like
another. In construction, paint can make metal
look like wood or make mild steel look like
stainless steel. This proves invaluable, allowing the
architect to create the illusion that their building is
constructed of a different material altogether.
Paint is frequently used for restoration of old
and historic buildings, to ensure that the original
style and appearance is passed on for future
generations to enjoy. The relatively primitive
paint technologies that existed hundreds of
years ago were adequate at the time, but over
the years have faded or disappeared altogether.
Drawing on current technologies allows us to
maintain that heritage for longer periods of time.
MANY INNOVATIONS
The coatings industry is constantly reinventing
itself to keep up with the demands of an
industry that moves at a fast pace. There are
many recent and forthcoming innovations. Some
of these have been specifically developed for the
construction industry, whilst others have come
from different markets but clever lateral thinking
has identified new end uses.
In the context of helping to maintain heritage
in older cities, many new buildings have the
potential to be applied with a coating that
can absorb pollutants (such as nitrous oxide)
from the environment. As we start to increase
occupant density through the development of
high-rise buildings, the potential for increased
pollution remains a risk.
Many commendable sustainable green
building initiatives act to limit negative
environmental impacts. However, that doesn’t
negate the need for continual product
improvement. A coating that can absorb
pollutants can help to achieve sustainability
aspirations and go some way to preserve the
appearance and durability of existing buildings.
We mentioned the issue of life to first
maintenance earlier; coating manufacturers in
the built environment are now looking to develop
self-healing coatings that can repair themselves
when scratched. This technology has originated
from the car coating industry and opens up
possibilities in relation to minor damage that may
occur in transporting pre-coated steel to site or
by lifting steel sections into place. Minimising
touch-up requirements has a direct knock on
effect to other trades on-site, and can potentially
prolong life to first maintenance and contribute
to maintaining the heritage of today’s buildings
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for generations to come.
Other technologies under consideration
at present include coatings with low surface
energy. This brings the benefit that it can resist
the build-up of ice, reducing both the risk of
weight and potential damage due to falling ice.
As the push for taller buildings continues
in some of the coldest countries in the world,
effects to mitigate against unwanted effects of
the extreme weather become vitally important
to consider.
INNOVATION – PAST, PRESENT AND FUTURE
In some ways the coatings industry can be
thought to be very traditional – with people still
using brushes and pots of paint, but this is often
far from the truth.
As we look further into the future, more and
more possibilities arise. Coating manufacturers
look to the designers of today and tomorrow
to envisage what challenges we may face. For
example, research is currently underway to
develop coatings that can generate electricity
when exposed to sunlight.
A tall building capable of generating its own
power supply is a powerful, but not impossible
concept. The savings on energy bills, heating and
reduced plant requirements soon become evident.
We are already seeing construction materials
enter the energy market with respect to solar
panels and wind turbines on tall buildings.
Increased energy efficiency through a coating
solution could provide an attractive alternative
to visual industrial plant requirements,
specifically as tall buildings become more
integrated in historic cities. Echoing the theme
of energy savings are requirements related to
thermal insulation. Research is also looking
into achieving improved thermal insulation
capabilities with thin film coating solutions.
For tall buildings, being able to achieve more
efficient designs with respect to façade and
cavity detailing for example, may permit better
energy ratings and reduced heating bills, all with
the benefit of using less space to ultimately
provide a greater floor area for letting.
Pushing the boundaries is not something
that holds us back. We’ve already witnessed
collaborations between the aerospace industry
and the power industry to use aerodynamic
coatings to increase efficiency of the wind
turbine blades.
Who’s to say that in the future, such
technology won’t find its way into tall building
design as structural engineers seek to optimise
their structure to mitigate against the effects of
excessive wind pressures at height? Essentially,
when it comes to innovation, the opportunities in
the construction product industry are endless.