Retrofit and conserving our architectural heritage can go hand in hand

The afternoon sun is shining through the bay window as I write this, and the room is pleasantly warm. But I know that in a few hours the warmth will be leaking out of the house and I shall be thinking about putting on the central heating.

We are being hit with two punishing issues at the same time: the steeply rising costs of energy, and the fact that the generation of much of that energy is warming the earth’s atmosphere to dangerously critical levels. Both of these issues are existential threats which, at the extreme, result in loss of life.

An essential part of the response to the crisis is to use less energy, by not having to turn on the heating in the evening. But we have a lot of poorly-insulated, or even entirely uninsulated, houses that leak heat like sieves, and cost a lot of money while doing so.

This is one of the biggest challenges facing all professions involved in housing. It is difficult enough to produce new housing that is well-insulated, let alone to upgrade old and deficient houses to a good standard of thermal insulation.

The streets continue to look in good condition today

In Balsall Heath in Birmingham, there is currently a project aimed at addressing this issue. The Department of Business, Energy and Industrial Strategy is funding the City Council to insulate, free of charge to the owners, or nearly so, up to 700 existing houses in the district.

In Balsall Heath there are a number of pre-WW1 streets of terraced byelaw houses: high-density, affordable, part of a walkable neighbourhood, but mostly possessing poor levels of thermal insulation. These repetitive terraces offer an opportunity for employing the economy of scale, rather than treating houses individually.

There is a good local precedent here. In the 1980s, the external fabric of these houses – windows, front doors, roofs, chimney stacks, front garden walls - was repaired and renovated by the City Council in a process named “enveloping”. It was mostly done free of charge to owners.

The Council had calculated that doing this wholesale, street by street, was cheaper than processing and funding hundreds of individual improvement grants. The streets continue to look in good condition today.

But there are architectural considerations too

The insulation work will be planned by the Council’s arms-length consultancy, Acivico, in partnership with a group of local residents which calls itself Retrofit Balsall Heath. A central figure here is John Christophers, architect and occupant of the Zero Carbon House, the first example in the UK of an existing house upgraded and extended to a zero carbon standard.

Retrofit Balsall Heath’s first task is to recruit a sufficient number of house-owners to make the economy of scale possible. The sales pitch is a financial one – do you want to reduce your heating costs?

So the project’s global rationale is to reduce carbon emissions, and its local rationale is to save households money. But there are architectural considerations too.

The most efficient way to insulate a brick-built house is to wrap it in insulation externally, just as we might put on an overcoat on a cold day. That way, the thermal mass of the brickwork retains the daytime warmth of the house, and radiates it during the cooler hours of the night.

Wrapping external insulation around the fronts of these terraced houses would obliterate this character

The byelaw streets of Balsall Heath, like Ombersley Road which is one of those targeted for treatment, have an architectural character shaped by brickwork details: hood mouldings, voussoirs, string courses, and corbelled eaves. It’s a modest character, and they are ordinary houses.

But architectural conservation, now informed by wider issues of sustainability, is no longer limited to special exceptional buildings. It embraces the ordinary, which forms the great majority of our environment.

Wrapping external insulation around the fronts of these terraced houses would obliterate this character. It might create a different character, but that would be more like Totterdown in Bristol, painted stucco, than Balsall Heath brickiness.

How much is local character worth? The cost of doing a hybrid installation – external insulation at the back, internal insulation at the front – is presumably greater than doing a completely external job.

It would also be less efficient thermally, would reduce the size of already small rooms, and would involve more disruption to households. But it would retain the houses’ character. Retrofit Balsall Heath is endorsing the hybrid approach, and it is to be hoped that it will be implemented.