Embodied carbon is the elephant in the room that may stymie all of our best-laid housing plans
One of the biggest myths we tell ourselves, in the context of the unfolding climate emergency, is that our normative expectations of the future can, more or less, carry on as normal. This applies equally to national political debates around how to solve the housing crisis, as to anything else. Whether on the left or the right, everybody agrees that more housing supply is the answer, although the manner in which that supply should be delivered of course differs markedly.
Yet, more often than not, the issue of expanding housing supply is discussed in near total isolation from the climate crisis and how we respond to it. The most recent figures from the Central Bank suggest that approximately 34,000 housing units will be required each year for at least the next decade – a figure which is largely accepted as gospel by all sides of the housing debate and likely to be included as the headline target in the Government’s forthcoming ‘Housing for All’ plan. Other estimates, such as those from Trinity College Dublin’s Ronan Lyons, puts the required number at closer to 47,000 per annum. Regardless, the general consensus is that an awful lot of new-build housing supply is required.
Private developers and the construction industry respond with glee to such projections, using them to put downward pressure on planning and building regulations, and to delegitimate public opposition to the ever increasing preponderance of very poor quality mass housing schemes. Activists on the left, on the other hand, argue that the government must commit to a doubling housing capital expenditure, as recommended by the ESRI, so as to achieve a build target of at least 20,000 public homes annually, insisting that anything less is just tinkering around the edges of an ever ballooning crisis.
The trouble is that building new housing is an incredibly carbon and energy intensive process, a fact which gets virtually no coverage whatsoever in the debates. While the data inevitably varies, research has shown that, on average, the carbon emissions associated with the construction of a new dwelling in Ireland, known as embodied carbon, is around 30 tonnes. This does not include the ongoing operational emissions associated with the use of the dwelling over its life-cycle or its eventual demolition, just the upfront carbon emitted during the manufacturing of the building materials, the transport of those materials to the site and the construction process itself.
Traditional cement and concrete based products, which remain highly predominant in new building in Ireland, account for roughly half of this embodied carbon. Indeed, concrete has been described as the most environmentally destructive material on earth, emitting 2.8 billion tonnes of greenhouse gases annually and responsible for 8% of global emissions, approximately three times that of aviation. The figures on worldwide concrete use are truly staggering. Since 2003, for example, China has poured more concrete every three years than the USA managed in the entire 20th century. If concrete was a country, it would be the third highest emitter of carbon in the world and it is the second most used substance globally, after water.
In Ireland, buildings are responsible for approximately 40% of energy related carbon emissions, with 28% coming from operational carbon and 11% coming from embodied carbon. However, while the policy and media attention has focused almost exclusively on the issue of operational carbon, such as the roll-out of energy retrofitting programmes, according to the Irish Green Building Council (IGBC), following the introduction of new building regulations in 2019, it is embodied carbon which now accounts for the major proportion (c.50%) of the total life-cycle carbon emissions of new homes.
Taking an average value of 30 tonnes of carbon per dwelling unit, building 34,000 houses would result in the production of over 1 million tonnes of emissions every year. The IGBC has estimated that, unless embodied carbon is radically reduced, constructing the 500,000 housing units envisaged as part of the National Planning Framework, and all the associated infrastructure, would result in between 38 and 50 million tonnes of carbon being emitted over the period to 2040.
The recently adopted Climate Change & Low Carbon Amendment Act 2021, however, requires that Ireland’s emissions fall by an annual average of approximately 3.5 million tonnes per year to 2030, halving our total annual emissions to just 31 million tonnes per annum by the end of the decade. It is evident that when housing supply and climate targets are set out side-by-side, the dilemma is stark. Developing that many new housing units while seeking to reduce emissions by that magnitude is problematic, to say the very least. The irony here is that if we were actually currently solving our housing crisis by providing much more supply, we would be simultaneously making our climate challenge worse, much worse.
At present, there are no firm proposals to regulate embodied carbon in Ireland. However, there are some promised changes at EU level and a number of European countries have already introduced measures which may ultimately have an influence here. However, given the immense lobbying power of the Irish Concrete Federation (ICF) and the general deference to the construction and property sectors, alongside the huge political pressure to urgently deliver new, affordable homes, it is probably unlikely to expect Ireland to be an early mover on enhanced regulation.
The difficulty of course is that concrete is both abundant and cheap, very cheap, accounting for just 3.4% of the cost of an average semi-detached house, according to the ICF. It is also a brilliantly adaptable building material, hence its ubiquity. The ICF estimate that delivering 500,000 new houses over the next 20 years will require the production of 1.5 billion tonnes of aggregates, which is also essential for concrete and cement production. The industry has therefore been busy lobbying for new fast-track planning rules to facilitate expanded quarry expansion, despite it’s rather dubious history of planning and regulatory compliance. To this day, there are dozens of illegal quarries operating throughout the country, causing significant environmental damage. Even during the recent high-profile mica and pyrite scandals, political criticism of the industry has been extremely muted.
The IGBC, on the other hand, whom have been a very lonely voice in trying to raise the profile of the hidden significance of embodied carbon, has been advocating for Ireland to commit to Net Zero Carbon Buildings, which would account for both the upfront and ongoing carbon emissions. At the very least, this would involve prioritising alternative and more sustainable construction materials which are low or zero carbon, such as the greater use of ‘green concrete’ and locally sourced timber products. The bad news is that many of these alternatives are in their infancy or face significant technical barriers to adoption, not least cost. Worse still, is that the main problem is really a matter of scale and the sheer demand for new buildings and urban infrastructure, which greatly outruns any carbon efficiency gains.
The IPCC Report published this week has unequivocally shown that we have entered the age of consequences and we are witnessing first-hand the devastating effects of global heating wreaking havoc around the world. Increasingly our lives will become dictated by rigorous adherence to carbon budgets, due to be published shortly, which will intersect all policy spheres, including housing, in multiple, complex ways. It is perhaps because of our inherited, implicit biases towards departmentalised, technical and supply-side solutions that we consistently fail to apprehend that climate change is a classic wicked problem. For example, we are already experiencing a chronic shortage in the supply of timber and any major expansion of the use of alternative low-carbon building technologies to address embodied carbon, especially the use of biomaterials, would have very significant knock-on implications for land use, particularly in the context of competing priorities such as biodiversity, carbon sequestration and food production. Similarly, Ireland is currently experiencing acute skilled labour shortages and lack of capacity in the construction sector, exacerbated by the pandemic, which may even see it have to choose between building new homes and retrofitting existing homes.
University College Dublin academic, Aidan Regan, has been to the fore in attempting to break down the silo mentality infecting housing policy debates, insisting instead that it must be seen as part of a broader urban crisis. To this, we urgently need to add the climate crisis – not just in respect of the relatively well understood issue of operational emissions, but also the very significant hidden challenge of embodied carbon. Moreover, achieving emissions targets directly calls into question Ireland’s preferred means of delivering new housing – the private market. Over the past decade, government has repeatedly foot-dragged on introducing higher building efficiency standards, fearful that increasing costs would be an impediment to supply and deter international capital. Given the basic profit fundament governing the property market, it is probably unreasonable to expect that it will be capable of delivering the homes needed in the context of an increased regulatory burden. This is, yet again, further justification for a much greater direct state involvement in the regulation and supply of new housing.
All of this of course will also have profound implications for how we plan and develop our cities and towns into the future. It is often said ‘the greenest building is one that is already built’ and it is estimated that Ireland has somewhere in the region of 200,000 vacant homes, enough for at least six years supply. Currently housing targets are allocated centrally and handed down from on high for local councils to prepare their zoning plans. It’s a simple numbers game. However, living within carbon budgets will mean that planning policy will have to become less about zoning, supply and densification within ‘compact growth’ principles but increasingly about how to avoid new building and infrastructure altogether through the creative reuse and repurposing of existing built stock within existing urban footprints. It will also mean that, instead of slavishly responding to market vagaries, planning will have to become more interventionist and directly involved in dictating what gets built, where, when and by whom (e.g. homes v. hotels etc).
Using a simple linear trajectory, the MarEI Institute at University College Cork has estimated that Ireland’s maximum carbon budget to 2030 is in, or around, 423 million tonnes. This budget will be subject to many competing demands (e.g. agriculture) and very complex decarbonisation challenges (e.g. transport). On our current trajectory we are estimated to emit 654 million tonnes over the same period. The challenge is without parallel. How we choose to spend our available carbon budget will be a matter of political will and choice involving very painful decisions, at least in the short-run, in staring down business-as-usual vested interests.
None of this, of course, is to argue against developing new housing. There is an absolutely necessity to provide high-quality net zero carbon homes. But as I have argued before, we may also need to downscale our taken-for-granted assumptions of very high future housing demand, which are substantially based on an extrapolation of historic trends of high economic growth and immigration into the future. In a climate changed world, past results are not a reliable guide of future performance. Lands zoned for housing may also need to be re-tasked for other uses, such as providing more natural green spaces and adaptation to ever more severe and disruptive weather events (e.g. flood attenuation, urban heat island effects etc.). It is hard to overestimate the revolutionary implications this will have for, not just planning, but also land markets, the entire functioning of the economy, fiscal policy, balanced regional development etc., and will require nothing less than a transformed planning culture.
We have not just entered the age of consequences, but the age of (very hard) choices.
Gavin Daly
Irish Planning Blog 
