A Brief History of Walls

Much of the housing in the area in which I live was built in the period 1870 to 1910.  Over the years gaps have appeared and the suburb has expanded to displace sheep from the surrounding farm land.  New houses have appeared on the lawns of grand houses, small orchards, market gardens and in a couple of places the side of a hill.  Whilst the style of building has changed, it is only in recent years that the method of construction has evolved.

The driving forces behind this evolution has been the Building Regulations and a change in the nature of home economics.  Prior to 2000, the general philosophy was to focus on capital costs, fuel for heating which is a major components of a home's operating costs was relatively cheap and a common way of getting a warm home after the arrival of North Sea Gas was to install lots of radiators.  This was not significantly different from the attitude of the Victorians who believed in the health benefits of ventilation and and whose homes needed a good supply of air to keep open fires burning, for them coal was relatively cheap.

Modern houses are built on a completely different principal, they have a higher capital cost but are intended to have much lower operating costs, not only that they are warmer.  The sketch below shows the difference between an old wall and a modern one.  For well over a century, the most houses were built with cavity walls which are just two single brick walls separated by an air gap and the inner wall finished with plaster.

Modern walls are significantly different, the outer layer of bricks might be similar, but the inner wall consists of a layer of foam insulation in front of blocks with good thermal properties and the finishing is insulated plasterboard.  In very rough numerical terms, old walls may have had U value greater than 2.0 watts per metre squared per degree C. whilst that of a modern wall will be less than 0.5.  In non-numerical terms you don't need much heating.  A proud owner of such a building I met recently did describe an alternative to a gas central heating boiler as a form of heating, but that may have been wishful thinking.  The sketches are not from the studying of Building Regulations, but the result of staring into building sites whilst walking my dog.

It is not only the construction of walls which has changed, but doors, windows, roofs.  Double glazing in sealed frames is now the standard and the thermal properties of these are significantly better than a single glazed sash window.

As someone interested in the concept of a "sustainable energy economy", I am sometimes puzzled by focus on energy generation.  I occasionally do a non-scientific survey of the contents of "science and environmental" sections of the media.  The stories range from the bizarre such as "Wind Turbine catches fire in Gale", "Planning permission application for new solar park", "Minister declares offshore wind farm open" and similar.  Only rarely is there an article on conservation or storage.  Its not hard to see why, few journalists or politicians can make much of a house brick, LED light or boiler controls.  Apart from a famous photo of Winston Churchill building a wall, I can't remember any interesting picture of an MP gazing lovingly at a brick.

Postscript

Shortly after I posted this, I heard a news report stating that during the prolonged winter of 2012/13 there had been 30,000 excess deaths (meaning more than normal) and that many of  these were due to old people living in cold homes.  In part, this is due to the way homes were constructed when energy was relatively cheap and plentiful.  Now that this is no longer the case, many homes, especially those of pensioners on low incomes are underheated.  Whilst I don't want to dismiss the value of retro-fitted insulation, in many cases a modest expenditure only makes the house less cold, not warm and does not cut energy bills.  Over a very long period, many thermal disasters will fall down or be demolished, but that will not do much for the generation currently living in them.  It would help if policy makers understood the problem and not ranted on about the imperfect working of the domestic energy market.