This month our editor-at-large discusses how he welcomes spring, as well as urban trees and the science of thermal mass.

Kevin McCloud on how he welcomes spring 2

Spring never really gets going till May. It starts to unwind in late February and falters its way through March. April usually looks promising but the shrubs, hedgerows and trees of Britain only start to deliver in May with the hawthorn blossom and the foliage of oak and ash. For the past 11 years, I have also marked this time of year with Grand Designs Live at ExCeL London, which happens with the regularity of an apple tree bursting into blossom in early May. The season seems to give visitors and exhibitors alike a new enthusiasm and interspersed among them are the weather-beaten diehards who know the building season, like nature’s own, is just beginning. I look forward to seeing you there with a spring in your step. Grand Designs Live, 30 April–8 May 2016 (0844 854 1348;


Fabric First

At Grand Designs Towers, we recently received apolite email from someone called Steamy Tea complaining that I was very, very wrong to use the term thermal mass when talking about how buildings perform: ‘There is no such thing in science. There is thermal energy and mass; they are not connected.’

Unscientific it may be, but it’s an accepted term in the building world, like ‘coolth’ and ‘flying buttress’, neither of which are scientific words. Moreover, a quick trawl across the internet will reveal that thermal mass is a common term and used by, for example, the Passivhaus Institut.

So what do I do? Steamy Tea’s email is not brilliantly helpful: ‘There is also the matter of thermal inertia, this is a difficult concept to understand as it is a six-dimensional problem – three physical dimensions, one of time and one each for heat capacity and thermal conductivity.’ Ijust about understand this, but know I'll have difficulty explaining it on television, unless I make a programme for the Open University that should have been broadcast on a Tuesday afternoon in 1973. This is an important point, because a ‘fabric first’ approach to building that employs stacks of insulation arranged around materials with high thermal mass (I mean six-dimensional inertia, I think) is the future for building in climates like ours. The idea needs communicating. So thank you to Steamy Tea for being the annoying physics teacher that I strongly suspect they are. If any readers can be helpful and elucidate as to what I should say, please write to me here at the magazine (This email address is being protected from spambots. You need JavaScript enabled to view it.). I’d like to clear the terminology up, before taking on the Passivhaus Institut and the entire construction science world.

 Kevin McCloud on how he welcomes spring 3

Trees for the city

A new piece of research promoted in Chartered Forester magazine shows that London’s eight million trees are worth £6.1billion to the capital. I like studies that monetise ecology because they get the bean-counters to sit up and listen. And politicians,

too. Boris Johnson is now going to invest further in this particular green bank by planting another 40,000 trees, half of them with London’s schools (it would be great if this were under the One Tree Per Child umbrella) and the other 20,000 via Trees for Cities ( which is planting a new urban woodland in Ealing.

The value that trees bring has been analysed for some time now, in terms of their health, social, psychological and amenity value. Trees for Cities cites research that shows people walk more, live longer and recover from illness more quickly with visual and physical access to trees. The new research shows that London’s trees remove 299 tons of PM10 particulates and 698 tons of nitrous dioxide pollution every year (total pollution removal adds up to 2,241 tons, worth £126million); they also absorb 2.3 million tons of carbon every year and alleviate flooding by attenuating 3.4 million cubic metres of water annually. Serious statistics

 Kevin McCloud on how he welcomes spring 1

Credit: Theo Cohen Photography; Matt Chisnall; Chris Tubbs

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