Lightning never strikes twice in the same spot – or does it.? You or in this instance, your building maybe more at risk than you think. With climate change experts predicting stormier weather in the future, the odds may be shortening!
Imagine yourself at the centre of a circle that extends 500 metres in each direction. If you are based in the highlands, statistically there is going to be one lightning strike within that circle every twenty five years. The tallest structures or buildings within that circle are, of course, the most likely to be hit. If there is a church spire within that radius it can therefore expect to be hit every twenty years.
If you live in Edinburgh, that frequency drops to about once in every five years. If you live in London, once per year. If you live on continental Europe or USA, even more frequently – Yikes !
If you are responsible for the management of a historic building, here are 3 tips that you might find helpful.
Rule 1 - Don’t Panic
The pictures can look dramatic and we are all taught form a young age to keep clear of electricity and the dire consequences of an electric shock.
Unless your building is tall or perched on top of a hill with nothing else around it, for most buildings the risk of being hit by lightning is so low that it is unlikely that any specific protection will be required.
Rule 2 – Don’t be bamboozled
The process for developing protection has been tried and tested over many years. The risk analysis involves some quite complex maths and technical terms such as “Lightning Strike Density”, “Risk Tolerance”, etc.
Although it is important to go through the technical analysis methodically, in the end, it is likely to boil down to quite a simple solution.
You may get a proposal that is full of jargon and formulas, and this can be an opportunity to justify an over specified, over priced and inappropriate solution for a historic building. An important question to ask yourself is, who is designing your system, an independent professional or a specialist installer who is also providing the quote for doing the work.?
If in doubt, get a second opinion.
Rule 3 – Keep things in perspective.
There are a range of outcomes that could occur, from the dangers to people from electric shock, physical damage to property and contents and damage to electrical systems.
There are of course various measures that can be taken to manage a lightning strike and reduce the risks, such as lightning conductors. A basic lightning protection solution can be surprisingly simple when designed well.
The most important thing to consider is risk to life and ensuring that there is no danger of electric shock.
The risk of physical damage to the building and loss of historic fabric needs to be considered more carefully.
Most Victorian churches can be repaired using appropriate conservation techniques without any significant heritage loss. A direct hit may cause some localised damage and that might be the only outcome that has to be dealt with. It could potentially ignite a fire which would cause more extensive damage, but this will take longer to establish itself. People will have an opportunity escape. Whether the fire service can attend in time to limit fire spread will depend on the location.
When you are considering a cathedral constructed in the 12th century, then the fabric is a little more precious and a higher level of protection maybe justified.
In most cases, unless you are a hospital, a data centre with critical communication infrastructure or a museum with irreplaceable artefacts, such as Van Gogh’s Sunflowers, it is unlikely that you are going to need any of the more technically sophisticated measures. If protection measures are required, they are likely to be relatively simple. With an intelligent solution the measures can be installed discretely.
This is particularly relevant when dealing with historic buildings, as a badly designed solution may do its job, but will be visually intrusive and could significantly impact on the architecture.
MAAC studio are accredited conservation architects and principal designers working with traditional buildings throughout Scotland.