Half-hourly metering explained — what it means for your business energy bill

What half-hourly means

A half-hourly (HH) meter records your electricity consumption in 48 half-hour intervals every day. That granular data flows into how your supplier prices your contract, how the network charges you for the flows on their kit, and how you can actively manage load to reduce bills.

Any UK site with maximum demand above 100 kW must be settled on a half-hourly basis. Increasingly, many sub-100 kW sites also have HH meters (via smart meter rollout) even though they're settled non-half-hourly.

Why HH tariffs look different

A typical SME contract quotes a single p/kWh unit rate and a p/day standing charge. An HH contract breaks the price down into commodity (wholesale energy), network transportation (DUoS/TNUoS), balancing (BSUoS) and non-commodity costs. Some of those elements are quoted as pass-through (you pay what the network operator charges) rather than baked into a headline rate.

The upside: much more accurate pricing that reflects your actual load profile. The downside: apples-to-apples comparison is harder, and you need to model total annual cost across multiple line items.

Agreed capacity — the hidden lever

Every HH site has an agreed supply capacity (measured in kVA). You pay a monthly capacity charge for that regardless of use, and you pay excess capacity penalties if you exceed it.

Right-sizing capacity is one of the biggest wins available. Many sites are booked at capacity levels from a previous era of operation and are dramatically over-subscribed. A capacity review — usually free — can knock meaningful cost off with no operational change.

Red / amber / green DUoS bands

DUoS charges vary by time of day and season. The 'red band' — typically 4-7pm on winter weekdays — carries the highest network charges. If you can shift load out of that window (batch processing, delayed shift starts, on-site storage), you materially reduce those charges.

Fixed vs flexible for HH sites

Fixed HH contracts (1-3 years) give the same certainty as SME fixed deals but require careful modelling because of the multiple pricing components. Flexible or basket-purchase contracts let you buy energy in tranches against the wholesale market and can outperform in stable markets — but need active management.

What to do if you're approaching 100 kW

If your peak demand is trending toward 100 kW — for example after new equipment, EV charging or heat pump installation — get ahead of the HH transition. Plan the metering upgrade, model the new tariff structure and consider whether now is the moment for a capacity review at the same time.