Avoiding common traps in energy savings (mis)calculation

2018. 1. 19.

Inconsistencies in the calculation of energy savings could derail global sustainability efforts, warn Tom Machinchick and Dr. Andreas Hermelink. Together, they investigate the effect of non-persistence in energy conservation measures on meeting the Paris Agreement and other carbon emissions goals.

Tom Machinchick and Dr. Andreas Hermelink are energy efficiency experts at Navigant. One of their latest reports analyses the markets and hurdles for energy efficient building technologies in Europe.
 
The savings related to energy conservation measures (ECMs) always come from a comparison of what would have been the consumption without ECMs and what will be the consumption with ECMs. Both pathways offer numerous traps that may lead to over or underestimating savings. Relative to meeting climate targets, overestimation of savings is an issue that can hinder attaining sustainability goals.
 
A major reason governing bodies or sustainability-related organisations overestimate savings is the persistence, or better to say, the non-persistence of energy conservation measures. For example, the savings gained by implementing an ECM drift or degrade during a measure’s lifetime.
 
The Coalition for Energy Savings, a European organisation that promotes energy efficiency, estimates that by 2030 about 18% (and by 2040 about 70%) of the energy savings from measures implemented before 2020 will be lost. Things get worse when measures taken to correct these losses can be counted as efficiencies gained during the new period—essentially double counting a single solution. So, no matter how stringent the goals, if persistence is not required and monitored and double counting of ECMs is not eliminated, ultimate goals will not be reached.
 
By the end of 2014 the European Council agreed that until 2030 greenhouse gas emissions will be reduced by at least 27% and energy efficiency and renewable energy consumption should be increased to at least 27%. In its Clean Energy for All Europeans package, the European Commission proposes raising the binding efficiency target to 30%. Additionally, energy companies must carry out measures to help their customers reduce consumption by 1.5% annually through the introduction of ECMs.
 
It is critical that savings related to these targets are not only achieved, but persist beyond 2030. This is especially important as these climate targets are tied to cumulative emissions reductions towards 2050 goals. Therefore, a reduction gap multiplies by the number of years it persists, and thus cannot be regarded as a single occurrence.
 
An explicit requirement for ensuring persistence of savings is not included in the Commission’s proposal. Although one might argue such a requirement may not be needed, measures to ensure persistence are required to avoid a gap accumulation. It is essential to closely monitor the actual emission track, to detect potential emissions gaps without delay, in order to understand their root cause, and to act accordingly in a timely manner.
 
What are typical reasons for non-persistence? Buildings provide some illustrative examples. Rebound effects may gradually eat up initial savings. Setting the thermostat a little higher than before the building was insulated is one example. This is not a problem if it is factored into the savings calculations, but oftentimes it is not. Feedback measures, like dashboards informing about consumption rates, may gradually lose their appeal, resulting in a return to initial wasteful behaviour. Ventilation heat recovery will work fine with clean filters, but once these get clogged, power consumption will rise. Gas boilers also require maintenance to keep their original efficiency. Even if control equipment for building systems is set up perfectly, operation hours of offices may change, for example, where the original settings no longer apply or are overridden—again, leading to higher consumption.
 
Many non-persistence issues can be tracked back to lack of proper maintenance. In the future, building automation and control (BAC) may better assist operators and users in providing alerts on needed maintenance and repair. Smart systems may be able to self-adapt to changes in operation.
 
A precondition for introducing such measures is awareness of what makes efficiency measure savings persist. The proposed amendments to the Energy Performance of Buildings Directive include suggestions for BAC playing a more prominent role in the future inspection of building systems. There is also a threat here. These systems are complex and if improperly used or set up, overridden, or if ad hoc remediation measures are taken, the smart system can be derailed, often leading to less efficient behaviour. Smart systems are a step in the right direction, but they certainly will not overcome all kinds of persistence issues.
 
Countries around the world are committing to global sustainability. But, commitment alone is not going to provide results if the actuals are not measured accurately or do not match the targets.
 
A key takeaway from this is that efficiency and sustainability goals cannot be removed from real-world dynamics, including the reality of energy efficiency project measure lives and dynamics. Utilities and regional transmission organisations such as PJM in the US, for example, include degradation rates on energy efficiency projects included in their generation capacity credits. Projects must be able to be measured to show demand reduction between certain critical peak load hours, and the incentives only last for 4 years before requiring recertification. This process ensures the accuracy and reliability of PJM’s generation capacity supply and demand calculations, which are essential for the utility to meet its generation requirements for its large customer bases.
 
Global sustainability goals and targets need to include this type of consistency and accountability for them to be effective in the long term.
 
Source: Euractive