Carbon’s X factor

The mass uptake of heat pumps and widespread comfort cooling could be the consequence of lower carbon factors, says WSP’s Mark Grace

The mass uptake of heat pumps and widespread comfort cooling could be the consequence of lower carbon factors, says WSP’s Mark Grace, who offers his predictions of what will happen to services design as the Grid decarbonises

Lower carbon factors for electricity in SAP will have a profound impact on the design of building services in dwellings. SAP 10 proposes a 55%  reduction in the emission factor for electricity, from 0.519 to 0.233kgCO2/kWh. It will be updated when the new Building Regulation Approved Document L is published in 2019 or 2020, so engineers are already looking at the consequences of lower carbon factors. Here are my predictions for what could happen to services design.

SAP 10 will result in substantially lower overall carbon emissions from buildings, as everything that uses electricity will have a lower environmental impact. The National Calculation Methodology will have to adapt so designers can still validate the performance of buildings against a ‘baseline’ (currently the ‘notional building’ in Part L). There will also be significant changes to assessment software by the likes of IES and EDSL.

Developers will pay more attention to direct electric heating, as it is cheaper and technically simpler than gas-fired heating. In the long run, gas boilers won’t be able to compete on carbon emissions. That said, gas is still set to be cheaper than electricity, so it’s not necessarily a win for the bill payer.

There will be fewer gas combined heat and power (CHP) specifications. The basis for using CHP in the past was its ability to generate (high emission factor) electricity from (low emission factor) gas, offsetting carbon emissions in the process. Unless a close-to-zero carbon biogas alternative becomes widely available, gas-fired CHPs will simply be unable to compete with electric alternatives.

Heat pumps will become the norm on virtually every type of building, and lower carbon factors will be a huge boost for innovation in this area; expect to see improved efficiency, viability, flexibility and even aesthetics. (People are going to see them, so they need to look nice.) There will also be an increased market for expertise in heat pump design, installation and maintenance. With that will come more affordable servicing – although the adoption of heat pumps will be a steep learning curve for clients, and there will be resistance in some quarters.

Heat pumps will become the norm – expect to see improved efficiency, viability and even aesthetics

The lower carbon factors will offer more of an incentive to mechanically cool buildings. Comfort conditions of UK buildings will improve during summer months as air conditioning becomes more widespread. There will be no more ominous overheating assessments, as we should be able to comfort cool with minimal perceived environmental impact.

Mechanical cooling will be hugely beneficial for climate change adaption, which we are required to demonstrate at the design stage on most projects. If cooling is incorporated in the original design, the building will be able to cope with rising ambient temperatures.

PVs will no longer be as beneficial in reducing CO2 as they are now, but there will still be a place for panels on a large scale. LED lighting will also save less carbon than it does today, compared with less efficient forms of lighting. Given that its specification is more to do with operational savings and controllability, however, I don’t see a reduction in its use.

There will be significant changes to the Passivhaus assessment methodology, as evidenced through the Passive House Planning Package. The 145kWh/m2 total primary energy target won’t be so challenging with lower carbon factors.

There could be issues with old infrastructure in cities as they struggle with the extra demand from people moving from gas to electricity, while a reduction in costs for a utility connection are possible as we move away from gas on some developments. (We’d need to consider how to address the perceived higher hot water demands, though – in kitchens, for example).

A rewrite of Local Development Framework policies on energy and carbon performance will be required. Current ones won’t be much of a challenge under the proposed new SAP, and – given that current policies are largely based on the European Energy Directive – it’s highly probable that Brexit will affect these too.

With electricity around four times the price of gas in the UK, low-efficiency heat pumps could increase clients’ energy bills, even if carbon calculations point towards the technology. There are also questions over heat pump performance, with reports highlighting the expensive operational costs. Some of this will be because of poor operation and/or control, but coefficient of performance ratings are still not particularly high for the technology across the year – although we can expect these to improve.

While few of my predictions are certain – with outcomes depending on the methodology used to evaluate the performance of buildings at design stage – one thing’s for sure: times are changing and engineers must get to grips with the competencies required to design electric services.

  • Mark Grace is an associate director at WSP