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When building from the ground up it’s moreimportant than ever to be green. ROGER HUNTlays the foundations for sustainable building.

SUSTAINABLE

foundations

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ABOVE Van Elle Smartfoot System: the Smartfoot beams being lowered into position

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a period of time, so the speed of construction isnot always a consideration.”

Nigel Chandler, commercial manager atCoinford, a company specialising in groundworkconstruction and design and build, comments:“The design of foundations is mostly put in placeby the client’s structural engineer. As contractors,one way we can influence the design offoundations and make them more sustainable isby suggesting and installing ‘post tensioning’. Thiscan reduce the quantity of concrete andreinforcement needed in the super-structures,therefore reducing its weight and subsequently thesize of foundations required.”

The BRE Trust report is clear that the most cost-effective solution may not necessarily be the onewith the least environmental impact. Even so, TimReynolds, senior consultant BRE and co-author ofSustainability in Foundations, emphasises that:“There are some very efficient systems out there atthe moment and ground floors have changedmarkedly over recent years with the moreengineered solutions.”

Reynolds suggests that piling is generally a bettertechnical solution than deep trench foundations.“Pilling is very risk free and a safer solution in thatyou don’t have people working and constructing indeep trenches. It is also a better sustainabilitysolution because it uses much less concrete,although the concrete is generally a higher strengthand there is some reinforcement in it.”

One specialist foundation engineering companyis Roger Bullivant. It offers a range of products andservices and John Patch, its director of marketingand sales, has noticed that packages combiningfoundations with a highly insulated ground floorhave become far more interesting to customers.

“We’re finding that with the cost of taking wastematerial off site, and indeed the cost of concreteand raw materials in making concrete, that these

Foundations potentially use significantresources. According to Sustainability inFoundations, a review by the BRE Trust, thetrench fill foundations for a typical semi-detached house comprise some 18m3 ofconcrete, or the equivalent of around 3,000kgof embodied carbon dioxide (CO2). Inaddition, excavated waste may need to betaken away. This need not be the case, newsystems and materials are enabling thesehidden components in the construction ofhomes to be as green as the buildingelements above ground.

Cost considerations, ease of construction and atendency to stick to ‘traditional’ techniques oftendictates foundation choice. One of the problems isthat there is no one fits all solution as every sitepresents different soil conditions while a variety ofother local factors must be considered such astrees, groundwater, contamination andconstruction noise and vibration.

Another important reason that foundations arenot always considered in sustainability terms isthat they tend to be left to a groundworkscontractor who might not have a particular interestin sustainability. The contractor may also be left outof the loop with little or no contact with thearchitect or other key team members who, in otherrespects, are working towards creating asustainable building.

At MDA, a company providing projectmanagement and quantity surveying services toresidential and commercial construction projects,residential director Keith Bowler brings someperspective to the issue. “At present, sustainableforms of foundation construction are seen to bemore expensive than traditional cast in-situfoundations, but they are faster to construct. Thisis not always advantageous to volumehousebuilders as they tend to build in phases over

systems are now cost effective even againstordinary strip foundations.”

Roger Bullivant’s SystemFirst is a modularfoundation and fully insulated flooring systemwhich the company claims will support any low-rise building in all ground conditions. SystemFirstrequires no trench excavation and componentsare manufactured off-site and installed on sitewith a significant time saving and reduction inconcrete use compared to traditionalfoundations. Despite this, it offers enoughmaterial to create thermal mass.

Van Elle’s Smartfoot is another modularfoundation system. Depending on groundconditions, it is installed with or without piles anduses concrete groundbeams that are cast offsiteand then craned into position and tensionedtogether to form an entire foundation.

“It is completely manufactured off site so there isno waste involved,” says Vic Handley, a director of,Van Elle. “What is delivered to site is very quick toinstall and requires less excavation, plant and

BELOW Roger Bullivant: Continuous flight auger (CFA)piling in progress. Concrete is pumped under pressuredown the hollow stem as the auger is withdrawn BOTTOM LEFT Roger Bullivant’s SystemFirst isinstalled on site

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labour for its installation and it significantly reducesthe time and waste on site. A significant benefit isthat, when a building has reached the end of itslife, these foundations leave very little scarring onthe site and can be reused elsewhere.”

Another system – Housedeck – is offered byAbbey Pynford. This is a concrete raft systemstabilised by small diameter bored or auguredpiles and has the advantage of eliminating costlyexcavations and reducing foundation installationtimes by up to 50 per cent.

“One of the advantages of Housedeck comparedwith traditional pile-and-beam options is that pilepositioning is not critical and it is therefore possibleto pile around existing obstacles such as drains,services or tree roots,” says Jenny Howard,business development manager.

Abbey Pynford has recently conducted studiesmaking a direct comparison between theembodied energy of Housedeck and traditionalpile-and-beam foundations which reveal that thesystem can reduce the carbon footprint of

foundations by at least a third whilst providingcost savings.

At the BRE, Tim Reynolds is keen to emphasisethe opportunities for using recycled or reclaimedsteel for piling and cement replacements likepulverised fuel ash (PFA) and ground granulatedblastfurnace slag (GGBS). He points to the factthat GGBS can reduce the carbon footprint byabout 50 per cent but each solution needs to beconsidered on a case-by-case basis.

“There are very important practical reasons whycertain foundations systems are used on certainsites and there are constraints on the materials soit’s about understanding how well they work,” saysReynolds. “It is important to have a process ofbetter site investigation so that the groundproperties can be utilised better.

For housebuilders, the ‘best practice approach’section of the Sustainability in Foundations reviewis particularly useful. It highlights everything fromthe very simple concepts such as “using betteraccuracy in setting out to minimise the size of

LEFT Van Elle Smartfoot System: the posttensioning operation in progress

RIGHT Roger Bullivant's SystemFirst isinstalled on site. The polystyrene insulation for

the floor fits into the galvanised steel frameBELOW Precast concrete piles being driven

using Roger Bullivant's quiet hammers

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“There are veryimportant

practical reasonswhy certainfoundations

systems are usedon certain sites”

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FURTHER READINGBRE Information Paper: Sustainability infoundations www.brebookshop.comNHBC Foundation design guide: Efficient design ofpiled foundations for low-rise housingwww.nhbcfoundation.org

CONTACTSAbbey Pynford www.abbeypynford.co.ukCoinford www.coinford.co.ukMDA www.mdaconsulting.co.ukRoger Bullivant www.roger-bullivant.co.ukVan Elle www.van-elle.co.uk

Read Roger Hunt’s blog: www.huntwriter.com orcontact him: roger@huntwriter.com

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is discussed in ‘Efficient design of piledfoundations for low-rise housing’, an NHBCFoundation design guide. The publication alsoprovides an overview of the environmental impactof foundation solutions ranging fromcontamination, waste, vibration, noise and airquality to embodied carbon in foundations.

Performance is another part of sustainability.Foundations which fail are not sustainable andultimately more resources will be used incorrecting problems. The NHBC guide suggeststhat instances where efficiency could have beenimproved include situations where foundationshave not met the design requirements, the type offoundation does not provide the best solution andwhere foundations have performed adequately, buthave been ‘overdesigned’.

Looking to the future, Van Elle’s Vic Handleysees a need to consider the broader picture. “Ifwe are going to look at things outside the normalconcrete foundations it needs everybody to gettogether to be able to look at those types ofinnovations and take them forward. We tend toget stuck in a time warp so need to look at othermeasures. We’ve looked at recycledpolycarbonates and plastics in the past, theyworked but they were quite expensive.”

foundations” to “using foundations as part ofenergy storage and productions systems”.

The latter is an area embraced by RogerBullivant. “We are often asked to incorporate theunderfloor heating pipes in the slab because, withSystemFirst, it is a finished slab rather than justbeing a subfloor and we design, supply andinstall,” explains John Patch.

Roger Bullivant is among the companiesincorporating ground source heat pumptechnology into the piles themselves. “The bigthing is there must be early involvement by usbecause you can’t retrofit this stuff. We still have along way to go in terms of people thinking of piledfoundations and engineered foundations as thenorm and then being able to get their minds roundputting geothermal loops in the piles,” says Patch.

Among those to have had direct experience ofincorporating ground source heat pumptechnology into piles is Coinford’s Nigel Chandler.“To put the pipes in and fix them to the rebar isanother operation and a lot more care is neededbecause you have got damageable pipes so ittook longer but only at the outset. Once we wereover the learning curve then obviously it justbecomes part of the operations.”

The use of geothermal piles for low-rise housing

ABOVE Roger Bullivant's SystemFirst galvanisedsections installed on piled supports

TOP RIGHT Precast concrete house foundationsbeams being installed onto precast piles and caps by

Roger BullivantBELOW SystemFirst is installed on site

BOTTOM A concrete raft foundation by Abbey Pynford'floats' above the ground

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