Housing: embodied carbon and climate

Housing: embodied carbon and climate

Written for a housing policy forum. Part 1

There are many ways for looking at housing: climate change, local environmental impact, community spirit, security, affordability, asset values &etc. However, finding a political narrative to address these issues is difficult because public awareness is low – I blame the ‘don’t inform and educate just entertain‘ BBC for that. The topic is also biased by self-interest, creating beliefs that cannot easily be shifted by facts. One of the most difficult issues is climate change, which is not given the importance it demands, in particular the greenhouse gasses emitted as a result of construction – the embodied carbon – is rarely mentioned. This first note is about embodied carbon.

Climate change

I have been watching the progress of Hurricane Irma for over a week now. It looks terrifying – worse than Hurricane Harvey that has flooded Houston. Irma will probably hit Florida or the East Coast of the USA by the weekend. Yet, on the West Coast, Californians have experienced severe droughts in recent years, and yesterday the Sacremento Bee reported Fires, smoke ravage Golden State from L.A. to Oregon border. In other parts of the world the number of people affected by climate change is considerably greater. Last week the Independent reported At least 41 million people affected in floods in India, Bangladesh and Nepal, UN says. In 2014 Carbon Brief reported Asian monsoon discovery suggests rains will increase under climate change:

“Asian monsoon rains will intensify as carbon dioxide levels and temperatures increase. That’s the prediction made by a new study [in the journal, Nature,] that also discovers the monsoon system has existed for at least 15 million years longer than previously thought.”

Just like rainfall from hurricanes and tropical storms, monsoon rains are getting more intense because as the atmosphere warms, it contains more moisture – but also as it warms, it creates more severe droughts.

Climate change and housing: the official perspective.

It is recognised in government circles, that housing has a role in greenhouse gas emissions, which drive climate change. A letter from Baroness Williams (Department of Communities and Local Governemnt) to Lord Krebs (Committee on Climate Change) discusses the two main public concerns of the UK Government on housing: building on flood plains and carbon emissions from heating houses:

“We recognise that the capacity of the sewer system to handle extreme rainfall can be an important cause for concern. In this respect it is important that pay attention to current national planning policy. The policy is clear that Local Plans should take account of flood risk from all sources, and our planning guidance explains that this includes risk from overwhelmed sewers and drainage systems. “

“We are also looking at heating systems. Heat accounts for around 45% of our energy consumption and one third of our carbon emissions. The long term goal is still to move towards more sustainable sources of heat; however, the role for conventional systems is expected to remain significant into the 2030s and it feels right that we should consider ways to save carbon and reduce bills from conventional heating systems.”

The Committee on Climate Change has an Infographic related to housing, which claims that the average UK home’s carbon footprint has reduced by 4.7 tonnes of CO2 between 1990 and 2014. Here is the top panel

Embodied carbon

This reduction, however, seems to be at odds with other publications – even from the CCC. These publications include the greenhouse gasses emitted in making the goods we import. These emissions are the embodied carbon in the imports.

The UK’s consumption footprint, which includes embodied carbon, was published in a DEFRA report UK’s Carbon Footprint 1997 – 2014:

The report says

“Figure 5 shows the relationship between three different measures of C02 emissions relating to the UK. The carbon dioxide footprint on a consumption basis is notably biggest due to the impact of embedded emissions from imports… The larger reduction in territorial emissions may be due to the UK economy further moving from a manufacturing base to a service base with a greater dependence upon imports and their associated embedded emissions.”

An example to illustrate this is shutting UK steelworks. This reduces the UK’s ‘official’  carbon footprint because the emissions from steel making stop. However, when we count imports of steel to replace this lost production from “China and the Rest of the World” our consumption footprint increases. This is because, on average, steel production in the rest of the world is even more carbon intensive that UK steel production.

The remaining carbon budget and the carbon ’embodied in’ construction.

An embarrassing issue for the housing market that has received little attention is the greenhouse gasses emitted when new houses are constructed. This is the embodied carbon in new buildings. To give this some context, it is helpful to compare this to the remaining carbon budgets.

The fifth assessment report of the Intergovernmental Panel on Climate Change (IPCC AR5 – in 2013) was the first to include an assessment of a “remaining carbon budget” – a finite amount of carbon that can be burnt before it becomes unlikely that 2°C of global warming can be avoided. Later they issued a budget for 1.5°C, which Carbon Brief updated in Six years worth of current emissions would blow the carbon budget for 1.5 degrees. – according to these calculations this is now five years.

In Is green growth a fantasy, I wrote

“Carbon Brief reports the remaining carbon budget to give a 66% chance of keeping global warming below 1.5˚C is 243 billion tonnes. That means, if humanity emits 243 billion tonnes more of CO2e, global temperature will rise to 1.5˚C above pre-industrial. Using the same calculations, the remaining carbon budget to keep below 2˚C is 843 billion tonnes.
World population was estimated recently at 7,317,801,293 by Worldometers. Dividing the remaining carbon budgets by the world’s population gives 33 tonnes of CO2e for a 1.5°C rise. For a 2°C rise this calculates as 115 tonnes per person.”

This is the ‘Worldwide personal carbon budget’: the remaining carbon budget shared equally among the people of the world. Because of missing feedbacks in the computer models used by the IPCC these calculations may be optimistic.

For a conventional house the emissions in building a new house can approach 100 tonnes CO2e. It is the embodied carbon in a new house. In my Submission to the Lyons Review on Housing, I wrote

One of the organisations that have taken embodied carbon seriously is the Royal Institute of Chartered Surveyors. I received an email from Bob Hill, last year, who has used RICS methodology. He says:

It would be useful in view of the government’s perceived need for more housing to assess embodied energy based on measured net materials as per the Standard Method of Measurement as compiled by the R.I.C.S. Body.

A practical approach would be to take a development approach and measure a property from the rear boundary fence down to the centreline of the estate road which would then be all inclusive for a full development and it would be advisable to incorporate a detached side garage with runway to the dropped kerb.

I have done an assessment and have come up with 91 tonnes which includes prelims.

Other sources suggest this is about right. The Guardian reported The carbon footprint of a house: 80 tonnes CO2e: A newbuild two-bed cottage.

There will, of course, be other buildings along with new homes: shops, offices and places of entertainment. Using conventional building methods this will increase the embodied carbon to over 100 tonnes CO2e per household. Clearly we must build differently.

Low carbon lifestyles.

Future notes will discuss the effects of house building on lifestyle carbon emissions. This is a preview from £20K housing – a lifestyle revolution, A new low-impact affordable economy from York Plotlands Association.

£20K housing – a lifestyle revolution, A new low-impact affordable economy

York Plotlands believes that the cost of living can be greatly reduced loosening the hold the rat-race economy has over us, freeing us for simpler, pleasanter and more sustainable lives. The first step in our vision is low cost housing. Our aim is to reduce the price of starter homes to under under £20,000: a tenth of the the average cost of housing in York today.

Geoff Beacon 8th September 2017

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