Mission impossible
As the Government adopts the CCC’s new targets on carbon reduction, Chris Yates analyses the UK’s unique triple energy mix and explains why we are uniquely positioned to decarbonise, minimise cost and diversify supply.
In the UK, we have a unique triple energy mix. We have an extensive gas network and comprehensive electricity coverage. Growth in district heating is positive. We are uniquely positioned to decarbonise, minimise cost and diversify supply.
For a long time, electricity - with its dependence on dirty coal-fired power stations - was the villain. Electricity usage was dis-incentivized in new buildings by Part L of the building regulations. But something has happened of late, the electric grid has become “low carbon”.
Gas has become the new CO2 emitting villain. Acting on advice from the Committee on Climate Change (CCC), Chancellor Philip Hammond announced in his spring statement a ban on gas connections to new homes by 2025. Apart from this furore-inducing statement, the proposal to increase the proportion of green gas in the grid was overlooked in the media. Perhaps the media was confused. After all, the two statements were seemingly at odds with each other.
In our new low carbon electricity grid, we must not ignore the major contributor to this greening: gas itself. The latest technology, combined cycle gas turbines or CCGT for short, uses the hot gas turbine exhaust to feed a steam turbine in tandem. They’re almost double the efficiency of a traditional coal fired power station. In cities such as Dusseldorf, even the spent steam is used to provide district heating, utilising up to 90% of the chemical energy bound up in the fuel. Renewables have come so much further than even the late, eminent Sir David Mackay predicted in his seminal work Sustainable Energy without the Hot Air. But, fuels and the efficiency with which we use them are evolving. We’ve been moving to lighter and lower carbon hydrocarbon fuels - from coal to oil, to gas.
An invisible hand has brought about some “proto-greening”. Starting with the discovery of petroleum in Pennsylvania in 1859 we moved away from coal as a source of oil products. Industries such as the lucrative “Cannel coal” illuminating oil industry disappeared overnight. As First Lord of the Admiralty, Winston Churchill moved our navy away from coal in spite of the fact that Britain had ample supplies of good steam coal, and no known oil reserves. He recognised that lighter fuels gave better technical solutions. And in the 1960s, a century after the discovery of petroleum, imports of liquefied natural gas (LNG) eventually put an end coal derived Town gas in the UK. Conversion to gas and the Clean Air Acts helped put an end smog.
According to market analysts Enappsys, Natural gas is now the dominant fossil fuel in Europe and accounts for 39% of the UK’s electricity generation mix (renewables account for 33%). Germany is the most recent country to pledge a phase out coal by 2038. We could say that green policies are working, but nothing happens without the will of the market. It’s simply not competitive to replace old coal power stations with new coal power stations.
The market will prevail to diminish the use of natural gas in turn, but it won’t happen soon enough to limit catastrophic climate change. We need to give this invisible hand the helping hand. We need to do some serious modelling!
We must stop using computing as a blunt "computer says no!" tool and start using it as it was intended: as a way to help society and humanity understand how complex systems work and therefore make better decisions. This is the real power of computing, joining the virtual world to the real world; tying building performance to economic and environmental cost.
We won’t do this with SAP or SBEM. Neither of these tools adequately represent the effects of climate on a building. This is especially true of cooling. A bare minimum for modelling this world are hourly tools (Energyplus, IES, TAS, Designbuilder and IDA ICE). A bit like “Economy 7”, the electric carbon intensity varies seasonally and diurnally, so why shouldn’t tools reflect this?
We need to model plant much better. Anybody modelling to the American ASHRAE standard 90.1 will attest that the rigour involved is light-years beyond Part L’s “NCM systems”. The CIBSE standard TM 54 Evaluating Operational Energy Performance of Buildings at the Design Stage shows promise. Yet it stops just short of being truly useful and fails to engage in the client’s vernacular - money. Both carbon and use of “per-square meter” metrics for benchmarking are ubiquitous, but abstract. They do nothing to connect with our innate money-senses. It takes very little to extend the TM 54 methodology to include tariffs. Let’s work more and more with cost consultants to “goal seek” the best paybacks.
And then there is measurement and verification. Lacking a defined standard in this field with have to go to our American cousins once more: ASHRAE Guideline 14. This can be used for establishing the effectiveness of energy conservation measures and for measurement and verification once the retrofit has taken place. It forms the basis of Energy Performance Contracting.
Can the market prevail? In the early days of the 2006 Part L update, I quizzed a CIBSE panel as to why Part L2A used carbon rather than cost as its metric in the same way L2B does in its Consequential Improvements payback. The reason was that costs don’t provide a robust enough case for carbon savings. And they were right. This was why the UK’s Green Deal failed - virtually no measures met the “Golden rule” of paying back within their warranty period.
Without a strong price on carbon it is hard to motivate for green solutions. Fossil fuels are subsidised in that we don’t pay for the waste disposal. Nicholas Stern, an eminent climate economist at the London School of Economics, is an outspoken critic of these subsidies and supports strong pricing for carbon of $40 to $80 per tonne. The Climate Change Levy goes part way to this.
Low-carbon electricity has come about by the accumulation of marginal gains. In spite of the increasing demands we place on the grid, it could continue: more renewable generation, more efficient turbines, low carbon fuels, biofuel, digitisation, energy storage, and more. We need to emulate this success to bring about low-carbon buildings. Paybacks will shorten as proxies for carbon such as the Climate Change Levy increase. Even more so, we will be in readiness when the UK adopts Lord Stern’s full recommendations.
Chris Yates C Eng MCIBSE LCEA is Building Physics lead with BDP
Picture credit: leowolffert/shutterstock.com
