Lime and Climate Change (The Story So Far) by Cliff Blundell

The ‘Historic Sector’ of the construction industry has always been a Cinderella.

Being lumped in under the title ‘construction industry’ hasn’t helped. Conservation of historic buildings has never been about ‘construction’; the building of a structure from scratch. It has always been about repair and maintenance of an already existing building, and thus its conservation – enabling it to last usefully and interestingly into the future.

The construction industry’s relationship with government has also had a lasting effect on the general perception of the ‘historic sector’ as economic and political imperatives cause our built heritage to be briefly highlighted and waved like a flag at times when it is politically advantageous to do so, only for the flag to be rapidly hauled down once more as the advantage fades. Again, the ‘establishment’ will revert to the usual lip-service due to that tiny sector of the much more economically important, housing-crises-led, new-build-obsessed construction industry.

Perhaps the most indicative marker of that attitude is the stunning ignorance of function, evident in Building Control’s ‘one size fits all’ rulings, inflicted upon the vast majority of an historic sector, that for decades Building Regulations did not even recognise as ‘historic’.

An historic building was one that was listed, or had something of special interest that made it worth attention. This gave it the status to be considered immune to the standing regulations, allowing ‘unusual’ materials, such as lime mortars to be used as these ‘special’ buildings had walls that needed to ‘breathe’, whatever they thought that meant.

They failed utterly to make the connection that the historic system of build utilised on these ‘special’ buildings was the same used by hundreds of thousands of pre-1919 buildings throughout the UK and completely different from modern construction. This huge number of solid walled structures was treated exactly the same as modern cavity-walled construction, having completely inappropriate regulations inflicted upon them, creating the damaging consequences that arise from the material and technical ignorance prevalent among those who imposed the regulations.

Official damage to people’s homes was being carried out across the land. The struggle to enlighten Building Control was met with petulance and intransigence in Wales. When Regulations devolved to Cardiff in 2013, at last, some progress was made. A BCO in Wales must consult with someone who understands the behaviour of the historic solid wall before inflicting any regulation. That has been of great benefit to the conservation of our built heritage in Wales, though thousands of solid-walled buildings are still covered in ‘regulation friendly’ vapour-impermeable cement, directly causing deterioration and therefore unsustainably.

Before our ‘victory’ in the battle of the Building Regulations, the last time something ‘very nearly happened’, was initiated by economic boom time in 2005 when the Heritage Lottery Fund, English Heritage (as they were), CITB Construction Skills and a new CITB staffed organisation, the National Heritage Training Group (NHTG) came together to publish a Skills Need Analysis of the Built Heritage Sector in England. At last an open recognition that a different skills set was necessary. This was followed the next year by the same process with Historic Scotland (as they were) and in 2007 with Cadw (as they still are) in Wales.

The Building Limes Forum became involved, as members with the right skills took part in trial initiatives to ‘Train the Trainers’, imparting their knowledge to staff at Further 3 Education establishments in an attempt to provide a core of ‘heritage skills sets’. BLF members also sat on the panel that wrote the lime content of the new Heritage NVQ 3, developed for this initiative to teach students about those most fundamental of conservation materials, Building Limes.

We actually seemed to be making progress in 2007. Then, of course, along came 2008’s financial crash, deep recession and austerity and suddenly it all disappeared with the funding.

Something that survived the collapse was the research and the analyses, and when our current viral crisis has died down, and we have had time to draw breath, we will have to put our minds to the next one: the looming threat of Climate Change, a challenge that could see life-threatening disasters on a far larger and more far-reaching scale than Coronavirus. That research provides ammunition for the approaching fight.

In particular, the NHTG research calculated the number of pre-1919 buildings in each of the three areas it covered, that represented our existing historic building stock. These figures give a clear view of the scale of the challenge, a challenge that was intended in 2007 to be met for the usual, slightly vague-sounding reasons that are difficult to define in any ‘punchy’, crowd-pleasing way.

NHTG’s stated reasons for proposed action were that historic buildings were ‘crucial to our understanding, not only of the past, but the present and the future, and have an important role in giving people and communities a sense of place’, and of course the economics of tourism – ‘visiting historic attractions is one of the most popular tourist activities’. True, but standard, ‘official’ and somewhat bland.

For most of us involved in the conservation of historic buildings, our personal reasons for that involvement can be equally hard to define. The buildings themselves of course, and a mixture of respect, love and admiration for the practical skills involved in the act of construction using traditional materials and the deeply satisfying achievement of conserving that delightful variety of aesthetic created by the wit and ability of those who went before – far more individual with a leaning towards emotional involvement. Both these official and personal motives are imperfectly distilled to a single concept, Heritage. The apparent motivation for our actions.

The NHTG surveys showed that in England there are 4,957,000 pre-1919 buildings. Dwellings account for 89% of total English historic building stock which in turn represents 20% of English homes. (Any fluctuation in these figures since 2007 is likely to be of an insignificant degree). In Scotland, 446,000 buildings represent 20% of homes in Scotland. In Wales, there are 497,000 pre-1919 buildings, 33% of Wales’ housing stock, a third of Welsh homes, the highest percentage in the UK.

A UK total, therefore, of 5,910,000 buildings, a significant figure that cannot be ignored, the vast majority of which are malfunctioning as homes, because that vast majority have been repaired and ‘maintained’ for decades by general builders who have no knowledge of the way solid walls are intended to function.

The principle of absorption and evaporation that maintains the integrity of the solid walled structure and creates dry, comfortable and healthy conditions inside these homes, is mostly lost on the non-specialist and it is the non-specialist who for two or three generations has been inflicting vapour impermeable, rigid materials (mostly cement) on these buildings and in spite of the overwhelming evidence of ‘unintended consequences’ within and without the structure, has continued to do so to the present day.

As readers will know, those ‘unintended consequences’ include water retention within the walls, chilling them in winter and causing the householders to burn more fuel than necessary to heat their homes, producing extra pollution in the atmosphere and extra strain on their pockets. These cold walls create perfect conditions for condensation within the home, which in turn attracts mould growth. Unhealthy conditions for the householder and their family (especially relevant at present).

The high volume of trapped water in the walls will rot anything and everything that moisture can deteriorate, accelerating decay and in extreme circumstances can affect structural integrity. This material and functional ignorance always creates a repetitive cycle of misguided repair and ‘maintenance’, each time using resources that are not only unnecessary but cyclically damaging to the building, its occupants and the environment.

The vast majority of those almost 6 million old buildings in the UK have been rendered unsustainable by a scandalous lack of willingness to try to understand them. In the glare of a rapidly approaching deadline to do enough to mitigate man-made CO2 before Climate Change reaches tipping point, our extremely ‘dirty’ construction industry must not only address the issue of new, new-build but must in parallel ensure that our existing solid walled building stock is as ecologically sound and as sustainable as possible.

There is only one way to achieve this and it is to return the designed function of absorption and evaporation that sustains our historic buildings, by the removal of the cement and other vapour impermeable materials from their walls and their replacement by the appropriate lime mortars, renders and roughcasts. Those simple acts will remove the ‘unintended consequences’ and those homes will become healthy for those living in them and sustainable for the sake of us all.

Retrofit’ using ill-judged modern materials and ‘solutions’ that attempt to force a building to behave in a way that was never intended, are not the answer and have already often proven unwise, creating more problems in the attempt to cure existing ones. More ‘unintended consequences.’

The reasons we give for our desire to conserve historic buildings will change from the difficult to define motive of ‘Heritage’, to the distinctly obvious, overwhelmingly important and necessary goal of ‘Sustainability’. The concept of ‘Sustainability’ will become the primary motive for historic building conservation. An old house with a hundred years already under its belt that can be sustained for a whole life cycle of hundreds more and then recycled at the end of its long life is far more valuable in ecological terms than building new.

Lime and its use is in the domain of the historic sector. The Cinderella of the construction industry will go to the ball as she is the only one who understands how to successfully use the material that will return this huge minority of our housing stock to its rightful place as a sustainable national asset, before the midnight hour strikes.

In 2002-07, the NHTG surveyed a route map leading to the recovery of our built heritage, and given the time, money, commitment and a stable planetary environment, that recovery may well have happened. They showed that the obvious route to that recovery is through the dissemination of the knowledge and skills that are held only within the historic sector. That education and training will have to start with us and within the ‘Lime Community’ there are those with the knowledge and skills to develop and maintain that initiative.

In the wider world of new-build, the current use of high energy, mass manufactured, indisposable materials will have to be severely restricted. The massive overuse of cement in new-build will have to be addressed.

The Centre for International Climate Research, Oslo, states that cement manufacture, leaving aside all other aspects of the industry (transportation, storage, waste etc), is the third largest contributor to anthropogenic CO2 after the burning of fossil fuels and deforestation. Excluding land use change, cement production could contribute 65% of all anthropogenic CO2 emissions, and as much as 8% of total global CO2 emissions. We should all find those figures shocking.

Even if this was partially mitigated by the use of renewable energy in manufacture, cement’s adhesiveness and rigidity prevent any meaningful recyclability of itself or of anything built with it, (except as hardcore), and worldwide, cement waste is responsible for 17% of landfill. After one use, it is virtually useless.

Limes’ ability to reabsorb up to 25% of the CO2 produced in its manufacture gives it a head start, and soft, flexible lime mortars allow the medium of a building to be dismantled and reused at the end of its life. And reused again, and again, into the future for as long as that medium lasts. Recyclability and harmless decomposition of waste represent a huge, ongoing and as yet incalculable contribution to CO2 reduction long into the future.

A new generation of ecologically sound building materials is already appearing on the market. Grown materials, such as hemp, jute and miscanthus that can be formed into blocks or sheets bound with lime mortar, are being used by some who are aware and who are willing to adapt.

Worldwide, cement production must be reduced. It should be used where it is impracticable to use lime. Where for instance, high compressive strength is necessary or in the constant presence of water, it is sensible to use it, but in most other areas of new build where there is a requirement for mortar or render , especially in domestic housing projects, the use of lime can only be beneficial to us all.

Does anyone out there seriously believe it is going to be business as usual? That we will go on using one coat, quick set, single use, throw away, noxious and toxic building materials?

In conclusion

There must inevitably be a drive towards ecologically sound ways of building, and that will mean less use of cement and concrete and other materials with high embodied energy and pollution rates, and greater use of low-energy, low-carbon, natural and less-processed materials that will be recyclable and will decompose harmlessly at the end of their usefully long lives. Building Limes already fit that bill. They do not need to be reinvented or developed or adapted to do their job. They will be fundamental in the rehabilitation of our huge pre-1919 housing stock and its environmentally sound survival into the long-term future, and will play a leading role in ‘cleaning up’ an industry that at present is a damaging but vital part of that future, so that it becomes something that is necessarily much more benign and thus an important global asset in the essential drive for CO2 reduction.

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