Eco-homes: There will be floods

As sea levels rise, will we still dream of homes by the coast? Adharanand Finn visits a bold new eco-home designed to rise above such concerns. Literally...

A floodplain on the edge of the North Sea may not be the ideal place to build your new home, especially with predictions of sea-level rises being ratcheted up with each new report. The latest global analysis, published earlier this month by the Intergovernmental Panel on Climate Change (IPCC), predicted a rise in sea levels by the end of the century of up to 58cm – higher than all previous predictions, which put the rises between 14cm and 43cm. The Association of British Insurers (ABI) warned last week that many new homes could be "unsaleable, uninsurable and uninhabitable" if they're built on floodplains. And the Environment Agency has also issued strong warnings that we must "avoid inappropriate development in areas at risk of flooding and to direct development away from those areas at highest risk."

Despite all this, the Salt House in Essex stands staring out at the rising sea, undaunted and beautiful. Far from being labelled as a reckless or foolish development, the Salt House has been unanimously lauded. It was recently named one of the best houses in the world by World Architecture News. Last year it was awarded the Manser Medal by the Royal Institute of British Architects (RIBA), an award for the best one-off house designed by an architect in the UK. The judges said the house was "breathtaking in the rigour of its design, detailing and execution". There was no mention of the folly of building on a floodplain.

The reason that the Salt House stands unconcerned by the risk of rising waters is VC simple. The house is built on stilts, so that when the floods come, as they surely will, the water will flow under the house, not into it. The stilts also mean that there are no foundations, which in conventional housing can collapse under the pressure of frequent flooding, while natural drainage on the plot is maintained.

And if climate change continues to outdo predictions, and the water levels rise higher than expected, the whole house can be jacked up and the stilts can be extended, raising the building even further from the ground.

It may sound innovative, and in many ways it is, but its architect, Alison Brooks, says that the inspiration for the design was taken from modernist post-war beach houses in the US. "Land was cheap in the US at that time," she says, "and so people who lived in normal houses most of the year could let loose and be quite experimental with their summer houses." It was common for these houses to be built on stilts to protect them from high tides.

So why did this simple idea never catch on in Britain? Brooks thinks it is because the coastline here was, until the 20th century, a working one and the idea that you could build a second house on the coast just didn't really exist. "When the coast was developed for recreation by the Victorians," she says, "they developed urban resorts and cities, such as Brighton."

As well as the unusual (in this country at least) stilt structure, the house employs a number of "dry-proofing" devices. Dry-proofing works around the principle of installing the most sensitive services – such as electricity cables – in parts of a house that can easily dry out after a flood. So, the base of the house is made from concrete, which dries easily. The wood panels on the walls are installed horizontally rather than vertically, so that if the bottom area gets wet you don't need to repair or replace as many panels. Electrics are situated in elevated positions, rather than close to floor level or under the ground. And fuse boxes in basements – well, that really wouldn't make sense in a flood plane. "It's mostly common sense, really," says Brooks.

Despite the beach-house style of the Salt House, Alison believes it could be used as a prototype for other houses. Almost a third of the three million homes set to be built in the UK by 2020 could be on floodplains, according to the ABI. Despite this, Brooks says that house-building in this country "is not dealing with floodplains in an interesting way".

"There are opportunities here to reinvent the suburban house," she says. Some of the proposals already being passed for houses on floodplains simply involve putting the living areas upstairs, with garages and other non-living areas downstairs. Brooks is not impressed. "This is terrible for street-life, and for maintaining a connection with the outside," she says.

Although the Salt House follows many of the most basic floodplain building principles, such as having a first floor, and putting the bedrooms up there, it uses raised decking outside as a way of connecting the inside of the house with the outside, which is particularly important for a house on stilts. In fact, at first glance, the house doesn't actually appear to be raised at all.

So is this design going to be rolled out on floodplains across the land? Brooks says that her firm, Alison Brooks Architects (ABA) has been working with large developers, but not on floodplains. "If we did," she says, "we'd use these principles for sure. But nobody has asked us yet."

Although it's not billed as the ultimate eco-house, the Salt House has many green features – as one might expect from a building that acknowledges in its very design the threat of global warming. But, like its flood defences, its eco-credentials intentionally don't shout too loudly. Brooks says that she believes a lot of eco-architecture has lost its way, turning houses into huge solar collectors at the expensive of form and function. "I believe in embedding eco-features into housing that works for people as living spaces. This comes first," she says.

This is partly why the house was built using extendable stilts. The planners had initially wanted the house to be built higher, but it would have then towered over the small oyster fishermen's cottages close by, creating a sense of separation from its environment.

The construction of the stilts structure was a relatively green process in itself because the ground didn't need to be dug up, disturbing the CO2 in the soil, and no earth had to be transported away and deposited.

The house is furthermore primarily built using sustainable timber, sourced from managed forests in Brazil.

It is also designed for maximum solar gain through devices such as carefully placed windows, and the use of a black slate floor in the kitchen, which acts as a heat sink, absorbing heat in the day and releasing it back into the house slowly at night.

While all such efforts to reduce the environmental impact of a building are of vital importance in the construction of any new house, because of its location the Salt House has been forced to shift its focus on to coping with the impact of global warming rather than trying to mitigate it.

In Britain, land is scarce and building on floodplains is, according to the Government at least, necessary to meet the country's housing needs. It's a dilemma that many other architects, as well as ABA, have finally begun to address, particularly abroad, and more specifically in the Netherlands, where two-thirds of the country is below sea level.

The Dutch firm Waterstudio designs houses and other buildings that actually float on the water. As Koen Olthuis of Waterstudio says, in an area prone to flooding, "the safest place to be is actually on the water".

Waterstudio's standard "watervilla" floats thanks to a hollow concrete box underneath it, which acts both to provide buoyancy and as a basement for the house. In most cases the house is moored to the shore on posts sunk into the ground, and, as the water level rises, the house simply slides up the posts.

Another Dutch architect, Herman Hertzberger, designed his first floating house in 1986 and refined the design for his watervilla in the town of Middelburg in 2002. The three-storey house comes complete with a steering wheel that so you can turn it – another advantage of it floating – to change the view, or to stay facing the sun. This has the energy-saving benefit of reducing the need for lighting and heating.

Perhaps the most advanced example of a flood-proof development is the Dutch village of Maasbommel, 60 miles east of Amsterdam. Twelve of the 46 houses in this picturesque community, which is only accessible by ferry, actually float on the water, while the rest sit on hollow concrete boxes beside the river. They look like ordinary waterfront houses, but if the river rises above its normal level, the concrete boxes float up, and the houses rise with them.

Many of the Dutch principles have been incorporated into proposals for Britain's first floating housing development in Princes Dock in Liverpool. According to the property agents, King Sturge, the 26 luxury homes are designed to appear like a row of multi-million pound super yachts, each providing a total living space of some 1,850sq ft.

Not quite the solution for building affordable homes on floodplains, then. Perhaps the Government should give Brooks a call.