Hi everyone,
Should we include fixed costs in calculating the costs of energy consumption? Fixed costs are in $ / kW, and variable costs are in $ / kWh. In the baseline model is a different number of kW and kWh as compared to the proposed building. So the variable cost is different in the proposed and baseline building and changes depending on the amount of kWh. However, we only know fixed costs for the proposed building. Should we make some calculations to calculate fixed costs also in the baseline building? Usage of the same fixed costs in the proposed and baseline building does not seem to us a good solution.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
December 6, 2018 - 3:53 pm
So it appears you are entering a specific electric rate from a utility into the models. If so you need to enter the entire rate into the model and not just part of it. You need to use the same rate in both models as well. You can have some variability in the virtual rate in this situation and that is OK. Anything that varies by more than 10% needs to be explained to the reviewer. A $/kW is not a fixed cost as the kW will vary month to month. This sounds like a demand charge and it is just another part of the rate. Fixed costs tend to be things like customer charges that do not vary month to month. Again all components of the rate must be included in both models.
Alternatively you can use a flat rate of $/kWh based on some sort of government reporting or local utility bills from a similar facility in both models. In this case the virtual rate would be identical in both models.
Justyna Gładysz
1 thumbs up
December 7, 2018 - 6:15 am
Thank you Marcus for response.
In Poland, when an investor signs a contract with an energy supplier, the $ / kwh rate is set and this cost changes every month. The contract also has a fixed amount, which depends on the expected maximum consumption (kW) and it is a fixed fee each month. For example, we know that the maximum power will be 500 kW and we pay $ 200 for it, and it's like that every month and we pay also for kWh.
Therefore, in the proposed building we count the cost form contract per kW as a fixed cost every month. This amount is not dependent on the actual power consumption, it is connected with the contract. However, it does not seem to me correct to count it in the same way in the baseline building.
If the baseline building were built, the contract with the supplier would look different and the fixed amount associated with maximum power in kW would be different. It would probably be bigger. We are wondering how to solve this problem.
Should we calculate the average price for kWh? We have annual consumption and total cost (we know what the kWh fee is and fixed charge) and we can divide the total cost by total consumption and get the average price of $ / kWh and use this value in the base building. However, this solution does not seem good to us.
The second option is to calculate how much the kW costs. We know the maximum power demand throughout the year. We also know the maximum power demand for the base building, so we can estimate what fixed amount would be on the contract with the provider for the baseline building.
I hope I have described it clearly.
Thank you for your help.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
December 7, 2018 - 10:23 am
OK based on your explanation it does sound like a fixed cost. You are required to use the exact same rate in both the baseline and proposed models by Appendix G. You cannot create a rate for the baseline that is different from the rate you use for the Proposed. Again your choice is to use the average cost per kWh as a flat rate or enter the rate applied to the Proposed. Either way the same rate must be used in the Baseline. Keep in mind that the baseline model is not at all a real building. Applying many of the HVAC requirements could not even be built in the real world. The comparison of the two models is entirely hypothetical. Designers often get caught in the mindset of trying to design the baseline and this should be avoided.
Justyna Gładysz
1 thumbs up
December 7, 2018 - 10:36 am
Thank you very much for your help.