carbon limited

Today Lord Turner’s panel met for the first time to discuss a concrete strategy for fufilling the UK’s commitment to reducing emissions by 60% by 2050 (and to consider upping the target to 80%). With around a third of UK emissions coming from housing, this sector will inevitably play a key role in their strategy. You might think we could rely on the Code for Sustainable Homes to get us there – after all, if all homes from 2016 are Code level 6 then there will be no net emissions from new housing. But unfortunately new homes are only a small part of the problem.

The graph below illustrates the predicted emissions from the housing sector by age of housing stock for the period 2002 to 2050. It shows that the overwhelming proportion of emissions will continue to come from houses built before 2002. The dotted lines represent the emissions from all housing required to achieve a 60% and 80% reduction in emissions vs 1990 levels. Emissions from each band decreases over time due to demolition.

Figure 1. Carbon emissions from housing sector by age of housing stock, 2002 – 2050

Clearly by focusing so heavily on new housing we’re ignoring the heart of the problem: existing stock. If we’re going to get anywhere near the 60% (or 80%) reduction in emissions, we need a strategy that drastically cuts emissions from existing housing. 

Yes, Code 6 is a good thing, at least in principle. All new homes should be zero carbon and they should be allowed to take advantage of off-site renewables provided strict rules on additionality can be met. So let’s take it as read that no net emissions from new homes is good and make it as easy as reasonably possible for developers to meet this target.

But dreaming about Code 7 isn’t productive. Neither is it productive to consider each new development in isolation. Sure the GLA  and some other planning authorities are insisting that new buildings are “district heating ready” but they continue to be limited by the Woking mindset, where small islands are considered independently. They’re not thinking big enough to make a real dent in emissions.

Instead we need to invest in improving efficiency and in systems that supply energy on the block and district scale. We need to use new developments as energy hubs that can reach into areas of existing stock with high density of demand. We need to follow the Danish model of investing in the central energy infrastructure required to move heat from the point of generation to the point of consumption. And then we can take advantage of the economies of scale allowed by large scale combined heat and power, energy from waste, and any other sources of low carbon heat. Messing about with a tiny CHP engine here and there will do nothing to address the larger issue.

You might point to past and ongoing feasibility studies into heat networks in London other cities and argue that things are already moving in the right direction. But these studies have been going on for years. Consultants get paid, reports get published, and nothing happens. Absolutely nothing. I hope Lord Turner will agree, it’s time to take action.

Notes on the graph. I took housing stock figure for 2002 and 2050 from figures from the Environmental Change institute. Break down in housing stock by age comes from the Survey of English Housing, figures available here (.xls) and I’ve assumed the proportions for all UK housing stock. Emissions from each type of housing stock up to 2002 come from GPG 171 (pdf) but I had to tweak them a tiny bit to get the overall totals to agree with the total emissions from the housing sector as published by DEFRA. For 2002 to 2015 I based the emissions on SAP with an allowance for cooking, appliances, and more realistic occupant behaviour. For demolition, I assumed that probability of demolition is proportional to the age of the house.