Five ways to cut electricity costs using your half-hourly data

A half-hourly (HH) meter records 48 readings a day, which makes it one of the most useful cost-control tools a business has. In practice, most of that data is never looked at. This guide sets out five practical ways to turn it into lower bills, with checks you can carry out on your own data.

Key points

• Start with base load: what the site draws when nothing should be running.
• Check nights, weekends and holidays for equipment left on.
• Move flexible load out of the DUoS red band where you can.
• Make sure your Agreed Supply Capacity matches your real peak.
• Use your load shape when choosing a contract and timing a purchase.

Before you start: get the data in a usable form

Ask your supplier, data service or broker for at least 12 months of HH data, ideally as a spreadsheet with one row per day and 48 half-hour columns. Each value is in kWh; double it to get the average kW demand in that half-hour. Check that the MPAN on the data matches the MPAN on your bill, and look for gaps or suspiciously flat periods that may be estimates before drawing conclusions.

If you would rather not do the number-crunching yourself, a load profile analysis will turn the raw readings into charts and figures you can act on.

1. Find and reduce your base load

Base load is the minimum demand your site draws, usually visible in the early hours. Find the lowest half-hours on a typical weekday night and on a Sunday. Because base load runs through all 17,520 half-hours of the year, a small reduction is repeated thousands of times.

Then list what genuinely needs to run at that time: servers, refrigeration, security lighting, ventilation, frost protection. Anything beyond that list is worth investigating. Typical culprits include compressed air leaks, heating or cooling left in occupied mode, heating and cooling running against each other, and equipment with no time control.

Base load checks

• Compare the overnight minimum with the daytime peak. A high ratio suggests equipment running when it is not needed.
• Do a night or weekend walk-round and note everything that is on.
• Check that building management system (BMS) schedules match actual opening hours.
• Compare weekday nights with weekend nights to see whether shift patterns explain the difference.

2. Cut out-of-hours waste

Overlay your opening or shift hours on the data and look at the hour after closing, weekends and bank holidays. A profile that steps down slowly over several hours after closing often means equipment is switched off by hand, late or not at all. Christmas and other shutdowns are a useful test: consumption then is close to your true unavoidable load.

The fixes are often procedural rather than capital: time switches, BMS schedules, a shutdown checklist and a named person responsible for checking it.

3. Move flexible load out of the red band

DUoS unit rates are highest in the red band, which usually covers weekday late afternoon and early evening. Exact times are set by each DNO region, so find your network operator and check its charging statement. Our guide to DUoS red, amber and green bands explains how the bands work.

Look at what runs during the red band and ask whether it has to. Candidates include forklift battery charging, pre-cooling of cold stores, water heating, batch processes and pumping. Moving even part of this into amber or green time changes your profile without reducing output.

4. Right-size your supply capacity

HH sites pay a daily capacity charge for each kVA of Agreed Supply Capacity (ASC), whether they use it or not, and excess capacity charges when demand goes over it. Your HH data shows your real peak. If you never come close to your ASC, you may be paying for headroom you do not need. If you regularly exceed it, you are paying excess charges and may need a formal increase.

ASC is measured in kVA, not kW, so power factor matters as well; see our guide to reactive power and power factor. Reducing ASC is not always easy to reverse if you later need the capacity back, so leave a sensible margin for growth and check with your DNO before making a change. A capacity review sets the figures side by side.

5. Use your profile when you buy electricity

Suppliers price HH contracts using your consumption shape, not just your annual total. A site that uses most of its power at night or at weekends costs less to supply than one that peaks in the early evening. Clean, complete HH data lets suppliers price your actual profile rather than a cautious assumption.

Your profile also helps you choose a contract structure. A site that can move load may see the benefit more directly with pass-through non-commodity charges, where changes in timing show up on the bill. A site that needs budget certainty may prefer a fixed all-inclusive price, and larger users with steady demand may consider buying in tranches. Our guide to fixed, flexible and pass-through contracts compares the options.

A simple monthly routine

Savings tend to slip back unless someone keeps watching. A short monthly check keeps the gains in place:

1. Download the latest month of HH data and check that it is complete.
2. Note the overnight minimum and compare it with the previous month.
3. Check weekend and holiday consumption against what should be running.
4. Total your red-band kWh and see whether it is rising or falling.
5. Record the highest half-hour demand, in kVA if your data includes it, and compare it with your ASC.
6. Check that consumption on the bill matches your data.

Get help using your half-hourly data

If you would like a second pair of eyes on your data, we can review your profile, check your bills and show you whether a different contract or capacity could lower your costs. If we cannot find a better option, we will tell you.

Request a free quote or bill check or call 07565 147 170.