10 Downing Street is the official residence of the Prime Minister. It’s one of the most famous addresses in the world and probably its most iconic front door, but I suspect that most people have never given a moment’s thought to its environmental performance.
There is, as you would expect, some history to the building. It was built, along with the rest of the terrace, between 1682 and 1684. The houses were designed by Sir Christopher Wren, but it’s the diplomat and property developer George Downing who gets the glory. He doesn’t really deserve it, as he cut a lot of corners on the building and didn’t dig the foundations deep enough. Consequently, the building has a much more checkered past than you might imagine.
After serving as a private home for many years, Number 10 was granted by the King to Sir Robert Walpole, usually considered the first Prime Minister, in 1735. It was intended as a gift, but Walpole refused and took it as an official residence to be passed on with the office. So it remained, although many Prime Ministers preferred their own grander houses and Downing Street eventually fell into disrepair, surrounded by gin shops and brothels. It was nearly knocked down in the 182os and with hindsight, it probably should have been.
By the time Disraeli acquired the house, it hadn’t been lived in for 30 years. He began the first of many renovations, adding running water. A few years later Gladstone added electricity and the first telephone. Central heating didn’t arrive until 1937. But by the 1950s the building itself was really on its last legs, “suffering from subsidence, sloping walls, twisting door frames and an enormous annual repair bill.” Once again, it was nearly bulldozed.
It was spared because of its historical value, but the whole building needed new concrete underpinnings, shoring up and strengthening. Rotten walls and floors were replaced in the 60s, and various refurbishments were made over the next two or three decades. That still wasn’t enough.
An official survey in 2006 found the building was no longer weatherproof. The heating and electricity was failing, there were leaks, and structural problems were resurfacing. The entire facade of Number 11 Downing Street has to be secured with steel pins. There was no question of knocking it down this time, but Tony Blair had to authorise another major refit, which is in fact ongoing.
And that brings us today. After centuries of fixing and tinkering with it, it is only in the last few years that its environmental performance has been scrutinised. It was pretty poor, so the most recent rounds of work have focused on improving efficiency. In 2009 a rainwater harvesting system was installed, with a large tank buried underneath the garden to keep the lawns green in times of drought. Low water use fittings were added, better insulation, new boilers and compact heat exchangers. Low energy lighting was fitted, with motion detection to turn lights off when rooms are unoccupied. A waste heat recovery system uses heat from IT equipment to heat water.
Being over 300 years old, it’s no eco-home. It still only gets a D rating for energy efficiency, but D is actually the average energy rating in Britain and for a Grade 1 listed building that is no mean feat. Last year Number 10 even won a rather prestigious BREEAM award for best in-use improvement, after reducing electricity usage by 13.5% in a year. If you’re so inclined, you can even go and look at the building’s real-time energy performance, although it wasn’t working when I checked just now.
It’s the age and listed status that make Number 10 an interesting addition to the series here. It shows that energy efficiency measures can be applied to even a busy and historically important building, and that there is enough flexibility within the Grade listing restrictions to make a difference. If you can retrofit Number 10, you can retrofit most houses.