12th November 2018

SAP 10: a small change that hints at big things for decarbonising Britain’s heat

Kevin Stickney, Managing Director of Erda Energy, argues recent building assessment factor updates are an overdue (and incomplete) corrective, offering a glimpse of the UK’s electrified future for heating

The Standard Assessment Procedure (SAP) 10 attracted little fanfare outside policy circles and the building and heating professionals when it was released in July. But, while policy and fiscal stimulus have turbocharged the sector, these assessment criteria – last adjusted in 2014 – have been a handbrake on decarbonising heat in the UK. This SAP update could be the start of a fundamental shift in how we approach the challenge.

SAP 10: lifting the handbrake is long overdue

The SAP standards list a number of factors used in assessing the environmental performance of buildings. Though not yet legally binding, the update gives the building sector forewarning on adjustments to factor into planning and design decisions.

So how will the standards change? The major talking point has been the carbon factor of grid electricity. Last updated in 2012 (though not effective until 2014), the current SAP figures stipulate 0.519 kgCO2/kWh. This compares to a carbon factor of 0.216 kgCO2/kWh for mains gas, meaning designers have been more likely to opt for gas-powered heating to meet targets.

However, in the six years since SAP 2012 was written, the UK’s grid has made great strides in decarbonisation. The update slashes the grid electricity carbon factor to 0.233 kgCO2/kWh, and 0.210 kgCO2/kWh for gas.

This changes the game for designers. Suddenly, on paper, combined heat and power systems and gas boilers look much less attractive compared to electric heating systems such as geo-exchange and ground or air source heat pumps.

Time to accelerate?

This is a positive step. Once in use, the new figures will bring us much closer to reality.

However, there are some pretty hefty caveats. First, note that 2017’s grid carbon intensity is already below that used in SAP 10. Then consider that the new factors won’t apply until something like 2020. If grid decarbonisation continues as forecasted that could mean the carbon factor is significantly outdated by the time it comes into force.

This would continue an ongoing trend; 10:15pm on the 8th May 2015 was the last five minute period with average grid emissions equal to or higher than 0.519 kgCO2/kWh. In effect, this means SAP 2012 has been distorting the decisions of building designers for years and could continue to do so.

However, BEIS’ consultation response suggests it will look into updating the carbon factor based on a monthly method to address this design flaw.

Whole system thinking

If an updated and upgraded SAP goes some way towards unshackling electric heat sources, there are other trends pushing that way too. Green Buildings Council has tirelessly campaigned for the reinstatement of zero carbon homes policy, which would all but preclude gas (barring some big leaps of faith about hydrogen). While recent research from the Energy Systems Catapult and Oxford University questions the fairness of the current balance between standing and unit rates for electricity supply and how low-carbon electric heat systems pay more than their fair share due to higher electricity usage, while other onsite generators like solar, pay less. They advocate for a rebalancing to remove this distorting influence on heat. Policymakers and influencers are waking up to the artificial barriers to electric low/zero carbon heat and starting to stir into action.

A balancing act

Of course, we must beware of unintended consequences. It would be a failure to set up electric heating as somehow in opposition to onsite renewable generation. Solar panels benefit a lot from current SAP arrangements, as by displacing heavily-penalised grid carbon they are disproportionately effective in helping developers meet emissions targets. This is a positive unintended consequence we cannot afford to lose.

However, our fundamental loyalty has to be to decarbonisation. The surest way to meet this challenge is to combine public support for new technologies with as clear a path as possible for established ones. Properly incentivised, the market will then deliver the quickest, most cost-effective route to cleaner heat.




Kevin Stickney
Managing Director

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