PROCUREMENT NOTEBOOK / ELECTRICITY
One bill. Two different questions.
kWh
How much energy?
kW demand
Which eligible facility peak?
01 / Introduction
The equipment quote arrives with an electricity figure. The facilities team asks what the new vending station will add to the monthly demand charge. Multiplying a daily kWh estimate by the demand rate will not answer that question: the units describe different things, and the billed peak belongs to a defined meter and tariff.
This guide addresses an equipment buyer adding a vending station to a shared building supply. It explains what to request before approving a business case, who should own the evidence, and how to compare equipment formats without treating a sales-page energy statement as a utility-bill forecast. It does not establish a demand rating for any WEIMI model or recommend changing refrigeration controls.
The primary reference is the U.S. Department of Energy’s Evaluating Your Utility Rate Options. It separates energy, demand and fixed charges, and explains why the magnitude and timing of site load matter. Its U.S. tariff examples are useful procurement questions; the actual local utility contract governs a project elsewhere.
02 / Quick Answer
Daily energy use supports the kWh part of the model. It does not by itself determine kW demand cost. If interval evidence is missing, show a stated sensitivity range and an unresolved approval item. Do not present an assumed peak contribution as a measured product advantage.
03 / Comparison Table
These are billing concepts, not interchangeable equipment specifications.
| Evidence | Question it answers | What it cannot establish alone |
|---|---|---|
| Machine kWh over a defined trial | How much energy was used in those conditions? | The facility’s incremental billed demand |
| Machine interval kW trace | When and how much average load did this equipment draw? | The building peak without matching site data |
| Whole-site interval trace | What combined load was present at the billed boundary? | The vending contribution without a baseline or comparison method |
| Applicable tariff and bill | Which periods, rates and demand rules apply? | Future equipment behavior or guaranteed savings |
A useful purchase file keeps all four sources separate and records how they are combined. It also distinguishes a physical meter measurement from a landlord’s internal cost allocation.
04 / Who Should Buy This
This review is most relevant to facilities buyers, campus operators and vending businesses whose host sites bill some electricity cost using demand. It is also useful when a landlord passes through utility charges or a concession agreement assigns electricity costs to the operator. Establish who pays before trying to optimize that cost.
A buyer on an energy-only tariff still needs a sensible energy estimate, but should not invent a demand charge that the account does not have. A buyer receiving a fixed monthly power allowance needs to examine the lease’s adjustment terms. A fleet manager with several buildings should assess each tariff and meter boundary rather than apply one site’s demand rate to the entire fleet.
Ask the facilities owner to approve the tariff interpretation, the operator to approve the trading and stocking assumptions, and the supplier to identify the exact quoted configuration. None of those roles can substitute for the others.
05 / How We Evaluate Smart Vending Machines
The three products below form a procurement shortlist based on public manufacturer listings, not independent laboratory testing. We verified their listed retail formats and use those distinctions to frame requests for evidence. We have not measured their interval load, compared their demand charges, or established which has the lowest operating cost.
Our review has three stages. First, confirm whether the commercial need calls for conventional snack-and-drink vending, open-door packaged-drink selection, or a two-cabinet assortment. Second, obtain electrical and operating information for that exact build. Third, evaluate a matched trial against the host site’s billing rules and load profile.
Save the configuration revision, meter identity, timestamp convention, trial dates, stock condition and operating settings. Describe any missing intervals or unusual building events. A quotation can be commercially attractive while its demand-cost estimate remains provisional; make that limitation explicit in the approval record.
06 / Key Buying Factors
- The billing boundary. Identify the utility meter, any downstream submeters and all shared loads included in the analysis. The nearest socket does not define the utility account.
- The tariff period. Read the demand interval, eligible time windows, seasonal rates and any minimum or look-back rule. DOE describes both time-of-use and non-coincident demand charges, and a look-back often called a ratchet. Do not assume every account uses the same rule.
- Timestamp alignment. Align equipment and building data to the tariff’s clock and interval boundaries. Document time-zone and daylight-saving treatment where relevant.
- Operating constraints. Record approved refrigeration settings, loading practices and trading hours. Do not interrupt cooling merely to make a spreadsheet peak smaller.
- Cost responsibility. Distinguish the utility’s bill from internal allocations, concession fees and electricity allowances. Allocate a charge transparently without calling it a measured marginal cost.
- Change control. Extra screens, optional cooling or a revised cabinet arrangement may change the evidence needed. Reassess the approved configuration when the order changes.
07 / Best Smart Vending Machines
“Best” here means the format most worth investigating for a particular retail brief. Public listings do not support a peak-demand winner.
WEIMI WM22 touchscreen snack-and-drink machine
The WM22 public listing identifies a touchscreen snack-and-drink format. Consider it when the project needs that retail model and an equipment-specific load trial can be arranged. Ask the supplier for the quoted electrical configuration and the conditions behind any daily-energy statement. A daily figure cannot establish its contribution to a building’s demand peak.
WEIMI single-door AI vision smart fridge
The single-door public listing describes a smart fridge for packaged drinks and compatible snacks, with customers opening the door and selecting products. It is not a juice-squeezing machine. Consider this format when open-door shopping fits the site. Request an interval trial that records the agreed stocking and door-use conditions; do not infer electrical demand from its AI checkout description.
WEIMI two-cabinet snack-and-drink station
The two-cabinet listing presents a main product cabinet and a secondary vending compartment. Consider it when the assortment brief benefits from both spaces. Confirm the final cooling, display and electrical arrangement of both cabinets. Do not simply double the demand assumed for a different single cabinet, or assume the two sections behave as one measured load.
08 / Feature Comparison
| Publicly listed format | Retail decision | Evidence to request for this study |
|---|---|---|
| WM22 touchscreen snack-and-drink machine | Conventional mixed-product vending brief | Exact build, operating settings and aligned interval trace |
| Single-door AI vision smart fridge | Open-door packaged-drink selection brief | Quoted options and documented stocking/door-use trial |
| Two-cabinet snack-and-drink station | Assortment planned across two sections | Confirmed electrical boundary covering both quoted sections |
Capacity, checkout format and visual presentation help select a retail concept. They are not demand-charge ratings. Request the same reporting period and interval convention for all candidates before comparing costs. If the trials cannot be matched, show the differences rather than force a numerical ranking.
09 / Cost & ROI Analysis
Hypothetical illustration only. Assume an invented tariff with a USD 0.15/kWh energy charge and a USD 12/kW monthly demand charge based on the highest eligible interval. Assume no ratchet, minimum, additional demand window, taxes or other variable charges. These are not WEIMI prices, measured machine values or a real utility tariff.
Assume added equipment uses 120 kWh during a month: the energy component is 120 × USD 0.15 = USD 18. Separately, assume aligned facility data shows a baseline monthly maximum of 80.0 kW. Under this simplified tariff, a modeled combined maximum of 80.5 kW adds 0.5 × USD 12 = USD 6 in demand cost. That scenario totals USD 24 for the two modeled components.
| Illustrative combined maximum | Change from 80.0 kW baseline | Additional demand charge | Energy + demand |
|---|---|---|---|
| 80.0 kW | 0.0 kW | USD 0 | USD 18 |
| 80.5 kW | 0.5 kW | USD 6 | USD 24 |
| 81.2 kW | 1.2 kW | USD 14.40 | USD 32.40 |
The maximum of the combined interval series is the important quantity in this simplified example. Adding the equipment’s separate maximum to the building’s separate maximum can overstate the result if they occur at different times. Looking only at the old building peak can also miss a new peak elsewhere in the month.
Use a credible baseline method; a simple before-and-after bill difference may include weather, occupancy or other equipment changes. For an investment case, subtract modeled incremental electricity along with stock, transaction fees, rent, service and other agreed costs from contribution. No sales, payback or ROI forecast follows from this electricity illustration alone.
10 / Best Choice by Scenario
Existing demand-billed office: select the retail format first, then ask facilities for aligned building data and the applicable tariff. Compare incremental combined peaks, including every eligible interval.
New site without a usable baseline: keep the demand estimate provisional. Obtain the account classification and use clearly labeled sensitivity assumptions until a representative trial is possible. Avoid turning the machine’s nameplate into a guaranteed bill increase.
Host building with a demand ratchet: have the tariff owner evaluate the look-back period. A lower current measured peak may not reduce billed demand immediately. Do not promise that a scheduling change will create a matching monthly saving.
Operator charged a landlord allowance: document the contractual allocation and reconciliation method. The economic decision may be driven by the allowance rather than marginal utility demand. Keep both calculations visible if both affect negotiations.
11 / Applications
During an RFQ, include a one-page electricity evidence schedule: tariff owner, meter boundary, requested interval format, exact equipment build and the person approving assumptions. This turns an ambiguous “low energy” request into a reviewable procurement task.
During a pilot, retain normal approved operating conditions and log stock loading, outages and relevant site events. Record enough context to explain the trace without claiming each peak has a known cause. Use qualified personnel and suitable measurement arrangements; this article provides no electrical installation procedure.
At acceptance, save the modeled result and its limitations alongside the configuration. After deployment, review the actual bill and interval data with the facilities team. A difference from the estimate should trigger an explanation of tariff, baseline or operating changes before a claim of product underperformance or savings.
12 / FAQ
Can I multiply daily kWh by a demand rate?
No. An energy quantity in kWh and a demand rate in currency per kW do not yield a valid demand charge. Apply the account’s demand calculation to the relevant load data.
Is every demand interval 15 minutes?
No universal interval is established here. DOE describes hourly or 15-minute interval data as typical advanced-meter information. Verify the actual tariff and meter convention for the site.
Is the machine’s highest kW automatically added to billed demand?
No. Its timing relative to all other loads and the tariff’s eligible periods matters. Evaluate the combined interval series and any other billing rules.
Does reducing kWh always reduce demand charges?
No. Energy can fall without changing the interval that determines billed demand. A look-back or minimum may also affect the bill. Review energy and demand components separately.
Should cooling be switched off during peak hours?
This guide does not recommend that. Product conditions and approved operation must be maintained. Any load-management proposal requires configuration-specific supplier and site review; do not assume a control feature exists.
Which of these three machines has the lowest demand cost?
The public listings do not establish that ranking. It requires configuration-specific operating evidence, the host tariff and aligned site data. The shortlist compares retail formats and procurement questions.
13 / Final Recommendation
Approve a vending electricity case when it shows which tariff applies, what the billed meter includes, and how the proposed load affects the eligible interval series. Keep kWh energy costs, kW demand costs and fixed or allocated charges in separate lines.
Shortlist WM22, the single-door AI fridge or the two-cabinet station according to the retail operation you need. Then request evidence for the exact build. Where evidence is missing, retain an explicit assumption and an owner for resolving it rather than awarding an unsupported efficiency winner.
Source boundary: DOE provides general utility-rate guidance, including time-of-use, non-coincident demand and look-back concepts. WEIMI pages establish listed product formats only. No local tariff interpretation, independent energy test, peak-demand rating or savings guarantee is claimed. Sources reviewed 18 October 2026.
14 / CTA
Planning a vending station for a demand-billed facility? Send WEIMI your country, retail format, proposed configuration and the electricity evidence your facilities team requires. Request a configuration-specific quotation and confirm what operating data can be supplied. Keep account credentials and private utility records out of an initial inquiry.
