How This Tool Works

📋 Purpose

UK households on dynamic tariffs can typically cut electricity costs by 30–40% and household carbon emissions by 50–70% by shifting flexible load — EV charging, dishwashers, heat pumps, washing machines — into the cleanest, cheapest windows. But that requires real-time data from two sources at once: National Grid ESO's 48-hour carbon intensity forecast (gCO₂/kWh, regionalised across 14 DNO areas) and the live tariff prices from suppliers like Octopus (Agile half-hourly, Go five-hour cheap rate, Cosy three-window heat-pump tariff, Tracker daily). This planner combines both, lets you add appliance profiles (EV battery and target SoC, dishwasher kWh, heat pump rated power), and recommends the top three windows per appliance — scored by a weighted blend of cost saving and CO₂ reduction versus a 'run now' baseline. Aggregated daily and annual savings dashboards quantify the value of dynamic-tariff switching and smart scheduling.

⚙️ How It Works

1
Enter postcode and select your tariff
2
Add appliances with kWh and constraints
3
Fetch 48-hour grid carbon and price forecast
4
See cheapest + greenest 2-hour and 4-hour windows
5
Schedule via timer, smart plug or app
6
Track daily £ and kg CO₂ savings

UK Grid Carbon & Smart Timing

Optimize your appliances for the cleanest, cheapest electricity

Updated just now

UK Postcode

DNO Region

Tariff Type

Your Appliances

No appliances added yet

Add an appliance to see optimal timing recommendations

Was this tool helpful?

Your quick feedback helps improve our tools

Complete Guide to Smart Appliance Scheduling in the UK

How carbon intensity and dynamic tariffs interact, why running an EV at 2 am is rarely the cheapest option, and how to capture both savings and emissions cuts.

📅 Last updated: 2026-05-01

Quick Tips

Jump-start your understanding with these essential tips

Octopus Agile prices track wholesale prices which broadly correlate with carbon intensity, but not perfectly. A windy night can be very green but only mildly cheap; a sunny midday can be very green AND moderately priced. The tool optimises a weighted blend of the two.

A 60 kWh battery costing 30p/kWh on a fixed tariff is £18 per full charge. On Octopus Go (5 hours overnight at 7p) the same charge is £4.20 — saving £14 a session and roughly 7 kg CO₂.

Cosy Octopus has cheap windows 04:00–07:00 and 13:00–16:00 — designed for heat pumps to pre-heat the home. Agile dynamic pricing can do better in windy weather but worse in cold-still conditions.

National Grid ESO publishes carbon intensity forecasts 48 hours ahead. The tool finds the optimal window across the full 48-hour horizon — sometimes the best dishwasher slot is tomorrow lunchtime, not tonight.

Both Agile prices and carbon intensity update every 30 minutes. The freshness badge tells you when data was last fetched. Re-check on cold-still weather days when forecasts shift quickly.

Running a dishwasher and washing machine in optimal windows saves around 60–90 p per cycle on Agile vs running peak. Per cycle this is small; over 200 cycles a year per appliance it is £120–£180 a year.

Step-by-Step Guide

Follow these steps to get the most from this tool

The tool resolves your postcode to the relevant DNO region (14 in GB) so the right tariff prices and grid carbon intensity are pulled. Octopus Agile prices vary by DNO; Cosy and Go are flat across regions.

Supported: Octopus Agile, Go, Go Faster, Cosy, Intelligent Octopus Go, Tracker, and any user-entered fixed tariff. The tool fetches Agile / Go / Cosy / Tracker prices live and combines them with grid carbon forecasts.

Pre-built profiles for EV (specify battery + target SoC), dishwasher (cycle length and kWh), washing machine, tumble dryer, heat pump (kW thermal). Add custom appliances with start time constraints (e.g. ready by 7 am).

Dual-axis chart shows carbon intensity (gCO₂/kWh) and tariff price (p/kWh) over the next 48 hours. Cheap+clean windows are highlighted; the tool flags the top 3 windows for each appliance.

Each appliance card shows the best start time, expected cost, expected CO₂, and savings vs a "run now" baseline. Schedule the appliance manually or via a smart plug / inbuilt timer.

Dashboard totals show daily and annual cost savings (£) and CO₂ reduction (kg) across all your appliances. Useful to justify upgrading to a dynamic tariff or buying a smart plug.

Advanced Topics

Deep dives for advanced users

National Grid ESO publishes the carbon intensity (gCO₂ per kWh) of GB electricity every 30 minutes, broken down to 14 DNO regions. It reflects the actual generation mix — wind, solar, nuclear, biomass, gas, coal, imports — weighted by emissions per fuel.

Typical UK range: 50 g/kWh on a windy summer night to 350 g/kWh on a cold-still winter evening when gas plants run flat-out. Average around 180 g/kWh in 2025.

Agile is half-hourly dynamic pricing pegged to the day-ahead wholesale market plus a fixed margin. Prices are published at 16:00 each day for the following midnight–midnight 24 hours.

Typical price range: -5p (negative, you get paid) to +35p per kWh (capped at the price cap level). Negative prices appear about 50 days a year on windy mild nights. Peak hours (16:00–19:00) are the most expensive almost every day.

Agile suits people who can shift load and have an EV or heat pump. It does not suit always-on usage like resistance heating, electric showers, or always-cooked-at-6pm households.

Octopus Go: 5 hours flat at 7-9p, default 00:30–05:30. Best for predictable overnight EV charging.

Octopus Go Faster: 4 or 5 hours, customisable start (00:30 / 04:30 / 20:30 / 21:30). For people who want flexibility on charging window.

Cosy: 3 cheap windows (04:00–07:00, 13:00–16:00, 22:00–00:00). Designed for heat pumps to pre-heat thermal mass.

Intelligent Octopus Go: smart-charging tariff for compatible EVs. Octopus dispatches the charge during cheap+clean periods between 23:30–05:30; you get the cheap rate even if the charge happens outside that window.

Heat pumps benefit most from being run when electricity is cheap and the building thermal mass can store the heat. Strategies:

Set point load shifting: pre-heat by 1–2°C in the cheap window, let the temperature drift down during the expensive window.
Hot water tank cycling: heat the cylinder during the cheap window only; ample insulation maintains temperature 12+ hours.
Modulate to grid: run at higher output (more efficient) when grid is clean and cheap, lower output when expensive.

Compatibility with smart heat-pump controllers like Homely and Honeywell Evohome makes this automatic.

The biggest savings come from combining: rooftop solar (4 kWp average ~3,500 kWh/year), home battery (5–10 kWh), heat pump and Octopus Agile / Intelligent Flux. The battery charges from solar surplus or cheap-clean grid windows, then powers the home through expensive periods.

Whole-home savings of £1,200–£2,000 a year are achievable on the right setup. Carbon footprint of household electricity falls 60–80% versus a fixed-tariff gas-heated home.

Frequently Asked Questions

Straight answers to common questions about this tool

For Octopus Agile, Go, Cosy or Tracker — yes, a SMETS2 smart meter on half-hourly settlement. For fixed tariffs the tool still works but only optimises for carbon, not cost.

National Grid ESO's Carbon Intensity API — official, free, updated every 30 minutes, with 48-hour forecasts.

Octopus Energy's public APIs for Agile, Go, Cosy and Tracker. Updated daily at 16:00 for Agile (next-day prices). Fixed tariffs are user-entered.

Usually yes if you can shift 1+ kWh of load per day to off-peak. On average Agile is 30–40% cheaper than the price cap for households with an EV or heat pump. For low-flexibility households it can occasionally be more expensive.

Yes — most modern EV chargers, heat pumps and smart plugs accept schedules or APIs. Octopus Intelligent Go and Tesla Powerwall users get automatic dispatch.

Wholesale price reflects supply/demand including imports. Sometimes cheap French nuclear imports lower the price but not the carbon intensity (which counts location-based emissions).

National Grid ESO carbon intensity forecasts are typically within ±15% at 24 hours and ±25% at 48 hours. Tariff prices for the next 24 hours are exact (already published); 24–48 hours ahead is estimated from forward-curve data.

It works for any single-meter premise on a half-hourly settled tariff. For larger commercial sites with HH metering and bespoke contracts, the principles apply but the prices won't match — bespoke import.

Other tools that pair well with this one