Modern methods means masonry

THB believes that the Government should be looking at ways of utilising the existing methods of construction

Construction has been at the centre of topical and political debate for some time now with everyone from politicians to designers to social commentators fanning the flames of the housing crisis.

At the centre of the conflagration is the future of affordable social housing, which is causing tension at all levels in the industry.

John Prescott's ODPM has been tasked with solving the problem, the solution of which has been largely voiced as being off-site, modular construction.

However, serious doubts have been raised, by the Government's own expert - Kate Barker - as to whether this 'quick fix' solution will indeed provide a sound basis for the nation's future.

And with recent comments made by Association of British Insurers (ABI) questioning the potential social and economic cost of fire in modular constructed homes the case for lightweight prefabricated construction is beginning to look flimsy.

From the point of the ODPM it is clear why it favours lightweight prefabrication.

On paper the method is fast and, like any politician, Prescott is keen to be seen to be taking action that will produce results.

However, build- time reductions in prefabricated construction do not add up.

Savings in time spent on site are offset by the time spent in production and a modern concrete masonry build can feasibly be built in six to eight weeks and, as Kate Barker concludes, up to 10% more cheaply.

However, the question remains whether speed should be the main consideration when building homes for families and key workers.

The key to building lasting communities is not simply to create as much housing as possible but to create the type of housing that people want to live in, feel proud of and will make a lasting home for future generations.

Barker's report supports this view: "Clearly just providing additional houses is not enough".

"The Government's strong focus on building sustainable communities is also vital.

The socially optimum outcome is not just overall numbers of houses, but also the type of housing".

Public confidence depends on the houses we build now being long lasting.

The truth of the matter remains that modular construction is still in its infancy and simply cannot prove its longevity or performance.

The last thing we should be doing is creating the brown field sites of tomorrow.

These concerns were echoed recently by a recent comment from the Association of British Insurers, whose spokesman expressed concerns about the potential insurance premiums associated with such experimental construction methods: "It is not apparent to us that anyone has looked into the resilience of [lightweight prefabricated] houses".

"What we build today has taken account of this so far.

If certain types of construction become associated with problems then they will be expensive to insure".

The ABI goes further in its response to the legislative proposals for the Scottish Fire and Rescue Services highlighting the additional expense that fires in affordable housing, typically funded or subsidised by the social sector, constructed by modular techniques could have on the public purse: "The adoption of modular building techniques, currently being promoted by ODPM in England for low cost housing projects, are of particular concern to insurers".

"The construction methods have variable fire resistant qualities and rely on good finishes, which must stay in tact and undamaged during occupation".

"The cost of repair in such constructions after a fire can be significant, particularly where the structure has to be dissembled in order to "slot in" a new replacement module.

The social and economic costs of major fires in such constructions will be enormous".

UK Government research suggests that socially excluded households are 31 times more likely to suffer fires than other households.

If in the future the majority of affordable houses are constructed using lightweight modular techniques the risk to life and the resulting economic cost to property could be immense, especially as there appears to have been little real impact in reducing domestic fire property losses despite public and private fire safety campaigns.

Modern masonry construction by comparison to lightweight modular forms produces a durable shell that can easily be refurbished and repaired after most fires, generally without extensive repair to the structure of the building.

Further to this, lightweight modular construction has a much higher build cost than masonry.

Questions remain as to whether an unproven, costly method is an appropriate end for public money, when the same budget could produce more robust, holistically more sustainable masonry built homes.

The answers lies, not in abandoning the materials that have a deep rooted affection in the public's mind or that the industry is already trained and equipped to deal with and replacing them with untried and untested methods.

We should be looking at ways in which these materials and methods can be employed innovatively to create long lasting, economically viable and robust homes, particularly in the social sector where the prudent spending of public money is a prerequisite.

The THB believes that the Government should be looking at ways of utilising the existing methods of construction that offer all the economical, social and durable characteristics that are already established within the construction industry in new ways, rather than pushing unpopular methods on the industry and the public.

The THB is sponsoring one such test project that aims to produce a low energy, healthy living environment that could provide a template for future low energy housing.

The project in Merton, South London is the brainchild of eco building lecturer Bob Harris and will see the building of four flats that will provide a healthy living atmosphere using materials that adhere to sustainable building principles.

The project utilises geothermal heat and thermal mass to provide all the hot water and heating for each residence for an annual bill of about GBP60 something that could be of particular relevance to the public sector.

The efficiency of the system is largely reliant upon the thermal mass of the building in this case supplied by the aircrete block external walls and the dense aggregate block internal walls.

To use thermal mass effectively all internal walls must be constructed using concrete blockwork of sufficient density and their surfaces must be in intimate contact with the surrounding air, requiring 'plastered' rather than 'drylined' finishes.

The same principal cannot be achieved using lightweight partitions.

When combined with the geothermal ground heat, supplied via a ground source heat pump, exceptional payback can be achieved compared with alternatives such as solar panels and photovoltaics.

The property's entire heating can be provided at a ratio of one unit of electricity producing four units of heat.

The project also has the backing of independent research.

Dr Hicham Adjali, Senior Lecturer in Engineering at Kingston University is conducting a research project to demonstrate the feasibility and viability (technically and economically) of ground source heat pumps for space and water heating in London.

Such is the interest in the project that it has already been awarded a top environmental award in the Green Apple Environment Awards where it was selected to be British Green Champion - top of its class for Fuel Power and Energy.

Particularly significant considering that the construction method of this highly innovative project is dependent for its overall efficiency on the thermal mass provided by the masonry walls and floors, rather than any of the lightweight or prefabricated building methods currently being championed by government as 'innovative'.

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