SUPPLY CHAIN
life with some structures serving for over 120
years. Plus Elhag points out that the Building
Research Establishment Environmental profiles
are only based on a 60 to 80 years service life.
“Sustainability is not a fashion or short-term
measure,” states Elhag. “Architects, specifiers
and engineers should always look at the bigger
picture while the other pillars of sustainability
should not be underestimated i.e. local sourcing,
social responsibility and serviceability.”
One of the most popular structural
floor solutions for commercial buildings is
hollowcore.
This system consists of concrete elements
cored along their length, with units generally
available as 1,200mm wide - although some
manufacturers produce up to 1,500mm, or as
narrower units of 600-750mm width.
tarmac's termodeck comprises a hollowcore slab with a pipe system to circulate air.
Depths are 150-450mm, depending on the
span and loading conditions; providing efficient, balls is that the slabs are 25% to 30% lighter than asked why they didn’t open the windows and
flexible solutions across all markets for most solid decks with up to 40% less columns. cited noise, desire to save energy or problems
building types. There are nine void former sizes available, with draughts,” explains Russell-Smith before
According to Daniel Westgate, sales engineer varying from 100mm to 450mm. adding that: “TermoDeck is a green alternative to
with Bison Manufacturing, there are many “There is a load reduction of between 1 air conditioning, heating and ventilation systems
advantages of using composite steel beam and 5kN/m
2
with a possible slab thickness of for new buildings that was invented in Sweden in
design. This is where hollowcore and solid between 200mm and 600mm and above,” adds the late 1970s.”
plank slabs are used together with insitu infill in Northam. Basically, the hollowcore slab includes a
conjunction with welded studs onto steel beams. Is it very different to equivalent solid slab? pipe system in which air circulates. Based on the
The benefits include: “It offers the same sound insulation features interaction between the mechanical ventilation
n Less floor beams required when compared to as for an equivalent solid slab,” states Northam. system and the thermal mass of the building,
other forms of construction He gives examples of where it has been Russell-Smith says the system is so discreet
n Hollowcore units provide lateral restraint used successfully: the creative arts building a building’s occupants will not even realise that
n Factory applied shear studs provide better at Huddersfield University and Tesco in the ceiling is acting as a large radiator or cooling
quality control Orpington, Kent. device.
n Fire stop blocks not required to protect top “The system offers lighter floors which How does it work?
flange of steel beams means, longer spans, quicker delivery, it saves “It starts with standard structural hollowcore
n 30% less fire protection required to the steel resources and offers earthquake safety, e.g. flooring planks and is modified to enable air
beams Lincoln,” says Hanson’s sales engineer. paths. Fresh air from the central air handling unit
n Reduced construction depth when compared Since it's an important factor, it's worth enters the concrete slab and slowly circulates
to non-composite solutions returning to the subject of precast concrete's before entering the room to provide fresh air,”
n Inclement weather is less of an issue when thermal mass benefits which is the material’s explains Russell-Smith before adding it can chill
compared to an insitu/metal deck ability to absorb, store and later radiate heat. or heat the passing air by controlling the slab’s
n Immediate working platform. “In all buildings, heat is generated by people, temperature.
Nor let it said that precast concrete can’t lend computers, equipment, lighting and solar gain,” In the summer, the hollowcore unit is used
itself to imaginative uses. explains Bison Manufacturing’s Westgate. as a thermal flywheel where the concrete is
Roger Northam, sales engineer with Hanson “Exposed concrete absorbs this heat and daytime cooled by passing night air through it which
gives the lowdown on two-way flat slab temperatures can be reduced by four to five enables it to chill the building the following day.
technology whose pragmatic name gives no hint degrees with passive systems.” Correspondingly, in the winter heat is absorbed
of its unusual design; namely a solid flat concrete A good example of an active system which in the soffit and recycled back into the building.
slab which includes recycled plastic balls, as ensures a building has good ventilation is “The system offers low energy consumption
‘void formers’. Tarmac’s Termodeck. and low carbon emissions with low capital costs;
“The basic idea of the technology is to Geoff Russell-Smith of Tarmac points out lower running and maintenance costs and, most
eliminate concrete in the zones of a slab where, that up until now natural ventilation has been importantly, fresh air,” says Russell-Smith.
from a structural standpoint, there is no necessity ignored by the public sector in the UK. All in all, this begs the question: Who would
for it and at the same time optimise the slab’s “Studies by BRE show that in 10 out of 16 have thought that precast concrete flooring could
thickness and building material volume,” schools tested, CO2 levels exceeded desirable offer such a variety of low energy options?
explains Northam. levels. For some reason we expect children to Not bad for an industry that one would not
Hanson's two-way flat slab technology includes recycled 'void formers', i.e. plastic balls, to create lighter concrete slabs.
The advantages to the void forming plastic need less fresh air than adults. Teachers were automatically associate with sustainability, is it?
SuStainable SolutionS December/January 2009 35
Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60