Danger in oversimplifying energy savings – built environment

When organizing energy procurement opportunities you can experience frustration with the need to use simplified language in order to tell your client how they will make the cost savings. The danger in presenting over simplified information is the data might be clearly shown the distortion of savings that may occur. However, the simplified information package cannot illustrate the effects when small but significant changes to operations, occupancy rates of building, seasonal variations, how government policy changes will impact on the cost equation.  What comes to mind immediately is the Carbon Price in government policy, and the opposition in Australia stating they will retrench that price – it then becomes important to consider how different energy retailers might treat it in the energy agreement – something very few thought about until recent times.

And, it appears universal that the common mistake in the information delivery is the over simplified explanations that can be interpreted as all actions the client takes is a linear function in terms of costs. When in reality the issue is the bigger the contract in terms of dollars the greater the impacts of what you do to affect energy used will affect your price paid for the total energy consumed.

Then we find we are not alone: It is common to make mistakes, and it all comes down to oversimplifying the estimates when presenting the cost savings.

When researching the phenomena it was found Lindsay Audin wrote  “Common Mistakes Made By Energy Managers” recently and we share much of his thoughts. So similar in fact, it is also what Co2Land org has been discussing with Ecoprofit Management (www.ecoprofitmanagement.com.au ). What we need to exercise care in is the data has a message, and to paraphrase into simplified information may miss very important part of that message:

1.    Beware of using averaged electricity rates. Customers in a tranche other than domestic tariffs will be rated for electricity charges for both how much electricity is used in terms of kilowatt-hours (kWh) and for how fast electricity is used in terms of kilowatts (kW) – The  “peak demand charge” and the variance of how fast you use electricity can be as much as 50% of a total bill change.

Note a) The danger in using averaged electricity rates as a simplify in estimating dollar savings from energy upgrades, is it is likely you might calculate an average electricity rate by dividing the total cost of electricity in a month by the kWh used in the same time period – therefore the rate includes the cost of peak demand in it.

Note b) Some upgrades to equipment may fail to reduce peak kW demand – examples are using motion sensors to control lighting needs and such measures will save kWh, but may fail to reduce peak kW demand because of changes to occupancy rates and timing of production loads changing to operational needs to be met. It also follows that controlled lighting might also only happen when the peak of energy use has already passed. In the case of motion sensors for lighting if they don’t cut peak demand, they won’t reduce the kW charge of the bill.

Note c) “This same problem arises with photovoltaic (PV) panels that generate power. A system rated (for example) at 100 kW will, at some point, provide that level of capacity – but not necessarily at a building’s peak time. Full PV output occurs when the sun is highest (between noon and 1 PM), unless the panels are mounted on a motorized platform that follows the sun. Commercial buildings usually peak between 3 and 5 PM, at which point PV output may have dropped considerably.” – Audin.

Note d) “Under a power purchasing agreement (PPA), a PV vendor owns the system and sells the output to the host customer at a small discount off the average utility price, typically for 15-20 years. Once again, that averaged price assumes all the PV power is being provided during the building’s peak. Studies have found that is often not the case. Depending on how much of one’s bill is for peak kW, the true value of the kWh from PV may be significantly lower than the vendor’s price.” – Audin.

Note e) It is then obvious that an averaged electric price overestimates dollar savings, and in all likelihood and unless there is data to prove otherwise, only savings based on the kWh can be assumed as a simple measure.

2.    Beware HVAC savings might not result from a lighting upgrade. Do not assume a watt for watt drop in cooling or assume a heating constant to replace the lamping output. It will not be a proportional saving of kWh in a linear fashion.

Note f) “Reducing lighting kWh cuts fixture heat output, but – for several reasons – that may not always translate into a proportional air conditioning (A/C) savings. For example, chillers run for only a portion of the year, while lighting is on most of the year. When lighting wattage is reduced in a room served by a constant volume air system containing electric reheat coils, a drop in cooling load may be made up – watt for watt – by an increase in reheat output. Not only will there be no cooling savings but even the kWh savings from the lighting upgrade may be negated.” – Audin.

Note g) “A 100% outside air system (e.g., serving a lab) may remove a significant portion of fixture ballast heat in its exhaust air instead of returning it to the cooling coil, thus mitigating some of the assumed A/C savings. If any of the upgraded light fixtures are outdoors or in uncooled spaces (e.g., stairwells, bathrooms, basements, mechanical rooms), their reduced heat output will never be seen by the A/C system. If, on the other hand, that reduced heat output necessitates an increase in winter heating through electric resistance baseboards, the net winter electric savings from the lighting upgrade may also be minimal.” – Audin.

3.    In Co2Land org’s mind the greater mistake is assuming maintenance savings will occur.  Repeated again and again are claims that new equipment will need less maintenance. It may be true, but in all likelihood it will have a cause and effect that might not be adequately assessed.  Consider this scenario: A new boiler is fitted with inverter technology and will require less maintenance. Staff will be cut because of this, or retrained, or reassigned elsewhere. But when maintenance is required of a harmonic distortion occurred the building’s maintenance budget will blow out and little or no actual measurable savings from new equipment will be reported. Admittedly it will most likely be in the preceding budget periods that this affect will show itself.

Note h) Research you case studies thoroughly, and do not assume marketing is telling the truth, the whole truth.

Our underlying message is to exercise caution when you try to explain with too little detail, and do not assume the other party is wanting you to explain all as a simplified explanation.  It might even pay to ask – can you make the time to understand all the implications?


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