Historic buildings need to be adapted to become energy efficient. Robert Adam urges heritage bodies and architects to embrace an approach that evolves, rather than contrasts with, the architectural language of our listed building stock.

Daniel Libeskind’s Royal Ontario Museum can be viewed as an extreme expression of the UNESCO Venice Charter principle, which states that “indispensable” new works must be both contemporary in nature and clearly distinguishable from the existing building.

As publications and institutions turn away from energy-profligate re-building, the focus will increasingly turn to the more than 400,000 listed buildings in the UK. And, as the timespan before a building is listed becomes shorter and shorter – 25 years is now possible for Grade I – this number will most likely accelerate.

Old buildings have an unusual and unrecognised status. By their very survival they have avoided demolition and reconstruction, often many times over. They carry a kind of carbon credit. The build-up of atmospheric carbon is a historic phenomenon and it is said that historic polluters carry more responsibility. Should, therefore, historic carbon conservers carry a commensurate credit? As carbon reduction is a future problem, this is unlikely to be an acceptable policy position. So, what do we do about often energy-inefficient heritage buildings?

Buildings are listed precisely to protect them from damaging change, which is arrested at the date of their listing. Up to that point, they were part of an unchecked process of change. From the moment of listing, change, while sometimes accepted, is controlled and usually severely limited by an administrative process. Making listed buildings more energy-efficient is likely to affect the very thing that caused them to be listed: their appearance, and the significance of that appearance as a historical record.

There are three aspects to this: energy source, climate control systems, and energy loss. In principle, there is plenty of energy. The earth’s core has more that we’ll ever want. The problem is how to harness it. Ground-source heating, boreholes and heat exchangers provide relatively benign sources of energy, with little visual impact. Solar PV panels, on the other hand, as generators of electricity, are far from invisible and, furthermore, as a developing technology can rapidly become obsolete.

Climate control systems – heating and cooling – are largely internal and can either be concealed or exposed as clear insertions, as were early space-heating or electricity, with a perceptually distinct identity.

Insulation is another matter. Thin walls, leaky windows, materials that are vulnerable to changes in temperature or humidity, are typical of older buildings. Thermal insulation has unavoidable bulk that transforms interiors and encapsulates built fabric. Externally it would transform most buildings beyond any original architectural integrity.

So, what is the solution? Setting aside the carbon credit, there are two sides to this: the Venice Charter solution and continuity of change. The UNESCO Venice Charter principle, whereby, “any extra work which is indispensable must be distinct from the architectural composition and must bear a contemporary stamp”, has been responsible for extensions and alterations that, while conserving some fragment of history, can utterly transform how it is seen.

This piece of 1964 design theory is based on the bizarre idea that history can somehow be falsified instead of just happening, but it still pertains in heritage policy and administration. It finds extreme expression in Daniel Libeskind’s Royal Ontario Museum or Zaha Hadid’s Antwerp Port House.

“Work which is indispensable”, in the present charged attitude to climate change, is easily applied to insulation or solar panels. Apply this philosophy to many of our historic buildings, given the inevitability of the impact of insulation, and the loss would be drastic.
Continuity of change implies a change in conservation philosophy with potentially less dramatic outcomes. As all buildings participate in an unavoidably changing world, this is part of their living character. Ironically, attempting to curtail this process is, in itself, a significant change in character, not always physically apparent. However, the extremity and speed of modern change, together with ‘false history’ theory, has tended to exacerbate the pressure to preserve.

If we can release the process of change but use it as a form of continuity, we can maintain our heritage as an evolving phenomenon. This requires two changes in practice: from designers, a commitment to work within a historic narrative rather than seek celebrity with overt contrast; from heritage administrators, a more open attitude to sympathetic change.