When and how you use energy is increasingly important. Used at the right time the same amount of energy can be low or high carbon/cost and low/high impact on our grid.

Many people will be aware that for non-domestic energy consumers and even some of our homes electricity prices vary over time but are you also aware that the CO2 emissions from our electrical grid vary? Generally speaking the CO2 emissions factor rises as demand rises, as we are required to use more fossil fuel plants. Although this might seem a bit esoteric it matters. For those of you doing carbon reporting for companies who  have to use the GHG protocol emission factors or energy modelling for new developments, (“Part L calcs.”) where we have to use standard emission factors it means we are increasingly inaccurate in our analysis. If for example you have a building that can shift demand to times when we have lower carbon electricity, such as the night, or the middle of a summer day then you can reduce CO2 emissions substantially, as well as help balance our electrical grid and reduce costs. This might seem unlikely for most of us; we use power when we need it, but this is increasingly not the case.

Demand Side Response (DSR), where you reduce energy demand briefly to help the grid balance itself and energy storage which can be charged at night and deployed at peak times are now being used at scale. This is of great benefit to our electrical grid, (you can get paid for it), and reduces CO2 emissions. The problem with this is that as your overall energy use won’t change it would show no benefit to the overall CO2 emissions in these calculations despite being a big benefit in reality.

Our energy system is being balanced constantly and the only way solar, wind and other intermittent renewables can deliver their energy successfully is by relying on the rest of the (fossil-fuel) power sector, demand side response and energy storage to balance them . Not acknowledging this, and using these standard emission factors in their CO2 emission reduction calculations is part of what has created a backlash in some quarters against them. (The graph at the top is an average from 2015 of each month over a day and shows some of the variation, however even this underestimates the difference because they are averaged months; they would be much more spikey if you looked at particular days in a month.)

Comparing solar power and LED lighting is a good example of the temporal issue in power generation. It generates during daylight, mostly in the summer when we need that power least; an LED lamp that saves the same amount more often during hours of darkness and in the winter, when we need energy most. As energy at peak demand periods is generally more expensive and CO2 intensive the saving is much more substantial. On this basis an LED lamp that saves 1kWh is much more beneficial than a solar array that generates 1kWh and yet our system of analysis does not notice that.

As a sector we should be explaining this clearly to regulators and our clients, yet I never hear it; perhaps we prefer the simple calculations rather than exploring the messy reality.

We get the same issue when looking at the medium/long term when making CO2 emissions calculations for new developments and advising clients who have existing building stock. Our electrical grid is decarbonising fast, our average electrical grid CO2 emission intensity this year was ~0.300kg per kWh. Compare this to the energy calculations for new developments under Part L of the Building Regulations we have to use 0.519kg per kWh and the GHG protocol UK factor of ~0.412. Even more importantly this emission factor is continuing to drop as we deploy more renewable power and nuclear, and swap coal for gas. Projections for 10 years from now are much lower again. All of this means that if you are making decisions on how to reduce CO2 emissions on a new building or existing stock you should consider this. For example the benefits of solar power will reduce over time and the benefit of solar hot water will stay the same as it is generally offsetting gas combustion whose carbon emissions remain the same.

At WSP|Parsons Brinckerhoff, (the company I work for) we wrote a paper about 18 months ago, Powering Ahead – Fast-Forward to the All-Electric City. In it we explained that the decarbonisation of our electrical grid will mean that the complete electrification of our buildings (and transport) will deliver massive CO2 emission reductions as well as the benefits in air quality and noise.  Because of the CO2 emission factors we are required to use we are making bad decisions about how we service buildings and the regulations don’t allow us to advise our clients as well as we could to reduce their CO2 emissions because we are using over-simplistic emission factors and not taking into account the long term.

If I was in a lift with a client and they asked me in a sentence to advise them on how to reduce their CO2 emissions most effectively I would say “You should electrify your buildings and transport now.” And I believe I would be right, but at the moment it wouldn’t appear right because of how we do analysis.

This goes right to the heart of the manifesto for this blog on energy analysis in the broad sense. There is more detail but the key four things are:

  • Analysis to be undertaken over a realistic period – For example if calculating the CO2 emissions savings of a solar farm/roof or new boiler then those calculations should use the appropriate emission factors over the realistic lifetime of that system, such as 20 years.
  • Analysis to be on the real impact on our energy system – At present in our calculations, (for buildings related issues) we use a standard emission factor (kg CO2 per kWh) for gas, electricity, etc. Years ago this may have made sense, it doesn’t any more.
  • Always consider “Real World” performance – We should seek to understand what the “real world” performance is likely to be, often known as “in-use” factors.
  • Consider the impact on other issues – When we undertake analysis energy efficiency and/or CO2 emissions are not the only relevant criteria; issues such as affordability and air quality, energy security and the impact on the wider energy system should be considered.

Electrification, demand management and energy storage are delivering massive benefits and will transform our sector with lower bills and CO2 emissions, but that will be delayed and bad decisions made if we fail to undertake good analysis. We need urgently to work out how we improve our current CO2 emission calculations.